Relationship Between Maternal Bone Biomarkers and Fetal Adiposity Through Normal Pregnancy

PURPOSE

To examine the association of maternal bone markers [sclerostin, soluble receptor activator of nuclear factor-κB ligand (sRANKL), osteocalcin, 25-hydroxyvitamin D3] with fetal intra-abdominal and subcutaneous adipose tissue deposition and birthweight during normal pregnancy.

METHODS

One hundred pregnant women (aged 30.4 ± 5.6 years, mean ± SD) with prepregnancy body mass index = 24.1 ± 4.6 kg/m2 were seen prospectively during each trimester. At each visit they were submitted to anthropometric measurements, a fasting blood sampling, a 75-g oral glucose tolerance test, and a fetal ultrasonogram. At birth, neonates had birth weight measurement.

RESULTS

In the second trimester, maternal sclerostin concentrations correlated positively with fetal abdominal circumference and birth weight; maternal sRANKL concentrations correlated positively with fetal abdominal subcutaneous fat thickness, sagittal abdominal diameter, and abdominal circumference. Fetuses born to mothers with greater (>254 ng/mL), compared to fetuses born to mothers with lower (≤254ng/mL), sRANKL concentrations had greater abdominal circumference, sagittal diameter, and abdominal subcutaneous fat thickness. Maternal serum sclerostin concentrations were the best positive predictors of birth weight. In the third trimester maternal sclerostin concentrations correlated positively with fetal sagittal abdominal diameter; maternal sRANKL concentrations positively correlated with fetal abdominal circumference and fetal abdominal sagittal diameter.

CONCLUSIONS

Maternal bone markers sclerostin and sRANKL may relate to fetal intra-abdominal adipose tissue deposition through as yet unknown direct or indirect mechanisms, thus contributing to birthweight.

Fetal growth velocity standards from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project

BACKGROUND

Human growth is susceptible to damage from insults, particularly during periods of rapid growth. Identifying those periods and the normative limits that are compatible with adequate growth and development are the first key steps toward preventing impaired growth.

OBJECTIVE

This study aimed to construct international fetal growth velocity increment and conditional velocity standards from 14 to 40 weeks' gestation based on the same cohort that contributed to the INTERGROWTH-21st Fetal Growth Standards.

STUDY DESIGN

This study was a prospective, longitudinal study of 4321 low-risk pregnancies from 8 geographically diverse populations in the INTERGROWTH-21st Project with rigorous standardization of all study procedures, equipment, and measurements that were performed by trained ultrasonographers. Gestational age was accurately determined clinically and confirmed by ultrasound measurement of crown-rump length at <14 weeks' gestation. Thereafter, the ultrasonographers, who were masked to the values, measured the fetal head circumference, biparietal diameter, occipitofrontal diameter, abdominal circumference, and femur length in triplicate every 5 weeks (within 1 week either side) using identical ultrasound equipment at each site (4-7 scans per pregnancy). Velocity increments across a range of intervals between measures were modeled using fractional polynomial regression.

RESULTS

Peak velocity was observed at a similar gestational age: 16 and 17 weeks' gestation for head circumference (12.2 mm/wk), and 16 weeks' gestation for abdominal circumference (11.8 mm/wk) and femur length (3.2 mm/wk). However, velocity growth slowed down rapidly for head circumference, biparietal diameter, occipitofrontal diameter, and femur length, with an almost linear reduction toward term that was more marked for femur length. Conversely, abdominal circumference velocity remained relatively steady throughout pregnancy. The change in velocity with gestational age was more evident for head circumference, biparietal diameter, occipitofrontal diameter, and femur length than for abdominal circumference when the change was expressed as a percentage of fetal size at 40 weeks' gestation. We have also shown how to obtain accurate conditional fetal velocity based on our previous methodological work.

CONCLUSION

The fetal skeleton and abdomen have different velocity growth patterns during intrauterine life. Accordingly, we have produced international Fetal Growth Velocity Increment Standards to complement the INTERGROWTH-21st Fetal Growth Standards so as to monitor fetal well-being comprehensively worldwide. Fetal growth velocity curves may be valuable if one wants to study the pathophysiology of fetal growth. We provide an application that can be used easily in clinical practice to evaluate changes in fetal size as conditional velocity for a more refined assessment of fetal growth than is possible at present (https://lxiao5.shinyapps.io/fetal_growth/). The application is freely available with the other INTERGROWTH-21st tools at https://intergrowth21.tghn.org/standards-tools/.

Automatic quality assessment for 2D fetal sonographic standard plane based on multitask learning

ABSTRACT

The quality control of fetal sonographic (FS) images is essential for the correct biometric measurements and fetal anomaly diagnosis. However, quality control requires professional sonographers to perform and is often labor-intensive. To solve this problem, we propose an automatic image quality assessment scheme based on multitask learning to assist in FS image quality control. An essential criterion for FS image quality control is that all the essential anatomical structures in the section should appear full and remarkable with a clear boundary. Therefore, our scheme aims to identify those essential anatomical structures to judge whether an FS image is the standard image, which is achieved by 3 convolutional neural networks. The Feature Extraction Network aims to extract deep level features of FS images. Based on the extracted features, the Class Prediction Network determines whether the structure meets the standard and Region Proposal Network identifies its position. The scheme has been applied to 3 types of fetal sections, which are the head, abdominal, and heart. The experimental results show that our method can make a quality assessment of an FS image within less a second. Also, our method achieves competitive performance in both the segmentation and diagnosis compared with state-of-the-art methods.

Role of Doppler ultrasound at time of diagnosis of late-onset fetal growth restriction in predicting adverse perinatal outcome: prospective cohort study

OBJECTIVE

Pregnancies complicated by late-onset fetal growth restriction (FGR) are at increased risk of short- and long-term morbidities. Despite this, identification of cases at higher risk of adverse perinatal outcome, at the time of FGR diagnosis, is challenging. The aims of this study were to elucidate the strength of association between fetoplacental Doppler indices at the time of diagnosis of late-onset FGR and adverse perinatal outcome, and to determine their predictive accuracy.

METHODS

This was a prospective study of consecutive singleton pregnancies complicated by late-onset FGR. Late-onset FGR was defined as estimated fetal weight (EFW) or abdominal circumference (AC) < 3^rd centile, or EFW or AC < 10^th centile and umbilical artery (UA) pulsatility index (PI) > 95^th centile or cerebroplacental ratio (CPR) < 5^th centile, diagnosed after 32 weeks. EFW, uterine artery PI, UA-PI, fetal middle cerebral artery (MCA) PI, CPR and umbilical vein blood flow normalized for fetal abdominal circumference (UVBF/AC) were recorded at the time of the diagnosis of FGR. Doppler variables were expressed as Z-scores for gestational age. Composite adverse perinatal outcome was defined as the occurrence of at least one of emergency Cesarean section for fetal distress, 5-min Apgar score < 7, umbilical artery pH < 7.10 and neonatal admission to the special care unit. Logistic regression analysis was used to elucidate the strength of association between different ultrasound parameters and composite adverse perinatal outcome, and receiver-operating-characteristics (ROC)-curve analysis was used to determine their predictive accuracy.

RESULTS

In total, 243 consecutive singleton pregnancies complicated by late-onset FGR were included. Composite adverse perinatal outcome occurred in 32.5% (95% CI, 26.7-38.8%) of cases. In pregnancies with composite adverse perinatal outcome, compared with those without, mean uterine artery PI Z-score (2.23 ± 1.34 vs 1.88 ± 0.89, P = 0.02) was higher, while Z-scores of UVBF/AC (-1.93 ± 0.88 vs -0.89 ± 0.94, P ≤ 0.0001), MCA-PI (-1.56 ± 0.93 vs -1.22 ± 0.84, P = 0.004) and CPR (-1.89 ± 1.12 vs -1.44 ± 1.02, P = 0.002) were lower. On multivariable logistic regression analysis, Z-scores of mean uterine artery PI (P = 0.04), CPR (P = 0.002) and UVBF/AC (P = 0.001) were associated independently with composite adverse perinatal outcome. UVBF/AC Z-score had an area under the ROC curve (AUC) of 0.723 (95% CI, 0.64-0.80) for composite adverse perinatal outcome, demonstrating better accuracy than that of mean uterine artery PI Z-score (AUC, 0.593; 95% CI, 0.50-0.69) and CPR Z-score (AUC, 0.615; 95% CI, 0.52-0.71). A multiparametric prediction model including Z-scores of MCA-PI, uterine artery PI and UVBF/AC had an AUC of 0.745 (95% CI, 0.66-0.83) for the prediction of composite adverse perinatal outcome.

CONCLUSION

While CPR and uterine artery PI assessed at the time of diagnosis are associated independently with composite adverse perinatal outcome in pregnancies complicated by late-onset FGR, their diagnostic performance for composite adverse perinatal outcome is low. UVBF/AC showed better accuracy for prediction of composite adverse perinatal outcome, although its usefulness in clinical practice as a standalone predictor of adverse pregnancy outcome requires further research. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Ultrasound markers for prediction of complex gastroschisis and adverse outcome: longitudinal prospective nationwide cohort study

OBJECTIVES

To identify antenatal ultrasound markers that can differentiate between simple and complex gastroschisis and assess their predictive value.

METHODS

This was a prospective nationwide study of pregnancies with isolated fetal gastroschisis that underwent serial longitudinal ultrasound examination at regular specified intervals between 20 and 37 weeks' gestation. The primary outcome was simple or complex (i.e. involving bowel atresia, volvulus, perforation or necrosis) gastroschisis at birth. Fetal biometry (abdominal circumference and estimated fetal weight), the occurrence of polyhydramnios, intra- and extra-abdominal bowel diameters and the pulsatility index (PI) of the superior mesenteric artery (SMA) were assessed. Linear mixed modeling was used to compare the individual trajectories of cases with simple and those with complex gastroschisis, and logistic regression analysis was used to estimate the strength of association between the ultrasound parameters and outcome.

RESULTS

Of 104 pregnancies with isolated fetal gastroschisis included, four ended in intrauterine death. Eighty-one (81%) liveborn infants with simple and 19 (19%) with complex gastroschisis were included in the analysis. We found no relationship between fetal biometric variables and complex gastroschisis. The SMA-PI was significantly lower in fetuses with gastroschisis than in healthy controls, but did not differentiate between simple and complex gastroschisis. Both intra- and extra-abdominal bowel diameters were larger in cases with complex, compared to those with simple, gastroschisis (P < 0.001 and P < 0.005, respectively). The presence of intra-abdominal bowel diameter ≥ 97.7^th percentile on at least three occasions, not necessarily on successive examinations, was associated with an increased risk of the fetus having complex gastroschisis (relative risk, 1.56 (95% CI, 1.02-2.10); P = 0.006; positive predictive value, 50.0%; negative predictive value, 81.4%).

CONCLUSIONS

This large prospective longitudinal study found that intra-abdominal bowel dilatation when present repeatedly during fetal development can differentiate between simple and complex gastroschisis; however, the positive predictive value is low, and therefore the clinical usefulness of this marker is limited. © 2019 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Expected-value bias in routine third-trimester growth scans

OBJECTIVES

Operators performing fetal growth scans are usually aware of the gestational age of the pregnancy, which may lead to expected-value bias when performing biometric measurements. We aimed to evaluate the incidence of expected-value bias in routine fetal growth scans and assess its impact on standard biometric measurements.

METHODS

We collected prospectively full-length video recordings of routine ultrasound growth scans coupled with operator eye tracking. Expected value was defined as the gestational age at the time of the scan, based on the estimated due date that was established at the dating scan. Expected-value bias was defined as occurring when the operator looked at the measurement box on the screen during the process of caliper adjustment before saving a measurement. We studied the three standard biometric planes on which measurements of head circumference (HC), abdominal circumference (AC) and femur length (FL) are obtained. We evaluated the incidence of expected-value bias and quantified the impact of biased measurements.

RESULTS

We analyzed 272 third-trimester growth scans, performed by 16 operators, during which a total of 1409 measurements (354 HC, 703 AC and 352 FL; including repeat measurements) were obtained. Expected-value bias occurred in 91.4% of the saved standard biometric plane measurements (85.0% for HC, 92.9% for AC and 94.9% for FL). The operators were more likely to adjust the measurements towards the expected value than away from it (47.7% vs 19.7% of measurements; P < 0.001). On average, measurements were corrected by 2.3 ± 5.6, 2.4 ± 10.4 and 3.2 ± 10.4 days of gestation towards the expected gestational age for the HC, AC, and FL measurements, respectively. Additionally, we noted a statistically significant reduction in measurement variance once the operator was biased (P = 0.026). Comparing the lowest and highest possible estimated fetal weight (using the smallest and largest biased HC, AC and FL measurements), we noted that the discordance, in percentage terms, was 10.1% ± 6.5%, and that in 17% (95% CI, 12-21%) of the scans, the fetus could be considered as small-for-gestational age or appropriate-for-gestational age if using the smallest or largest possible measurements, respectively. Similarly, in 13% (95% CI, 9-16%) of scans, the fetus could be considered as large-for-gestational age or appropriate-for-gestational age if using the largest or smallest possible measurements, respectively.

CONCLUSIONS

During routine third-trimester growth scans, expected-value bias frequently occurs and significantly changes standard biometric measurements obtained. © 2019 the Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Impact of biometric measurement error on identification of small- and large-for-gestational-age fetuses

OBJECTIVES

First, to obtain measurement-error models for biometric measurements of fetal abdominal circumference (AC), head circumference (HC) and femur length (FL), and, second, to examine the impact of biometric measurement error on sonographic estimated fetal weight (EFW) and its effect on the prediction of small- (SGA) and large- (LGA) for-gestational-age fetuses with EFW < 10^th and > 90^th percentile, respectively.

METHODS

Measurement error standard deviations for fetal AC, HC and FL were obtained from a previous large study on fetal biometry utilizing a standardized measurement protocol and both qualitative and quantitative quality-control monitoring. Typical combinations of AC, HC and FL that gave EFW on the 10^th and 90^th percentiles were determined. A Monte-Carlo simulation study was carried out to examine the effect of measurement error on the classification of fetuses as having EFW above or below the 10^th and 90^th percentiles.

RESULTS

Errors were assumed to follow a Gaussian distribution with a mean of 0 mm and SDs, obtained from a previous well-conducted study, of 6.93 mm for AC, 5.15 mm for HC and 1.38 mm for FL. Assuming errors according to such distributions, when the 10^th and 90^th percentiles are used to screen for SGA and LGA fetuses, respectively, the detection rates would be 78.0% at false-positive rates of 4.7%. If the cut-offs were relaxed to the 30^th and 70^th percentiles, the detection rates would increase to 98.2%, but at false-positive rates of 24.2%. Assuming half of the spread in the error distribution, using the 10^th and 90^th percentiles to screen for SGA and LGA fetuses, respectively, the detection rates would be 86.6% at false-positive rates of 2.3%. If the cut-offs were relaxed to the 15^th and 85^th percentiles, respectively, the detection rates would increase to 97.0% and the false-positive rates would increase to 6.3%.

CONCLUSIONS

Measurement error in fetal biometry causes substantial error in EFW, resulting in misclassification of SGA and LGA fetuses. The extent to which improvement can be achieved through effective quality assurance remains to be seen but, as a first step, it is important for practitioners to understand how biometric measurement error impacts the prediction of SGA and LGA fetuses. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Extraction of foetal ECG from abdominal ECG by nonlinear transformation and estimations

BACKGROUND AND OBJECTIVE

This paper proposes a simple yet effective method for the extraction of foetal ECG from abdominal ECG which is necessary due to similar spatial and temporal content of mother and foetal ECG.

METHODS

The proposed algorithm for extraction of foetal ECG (fECG) from abdominal signal uses single channel. Pre-processing of abdominal ECG (abdECG) has been done to eliminate noise and condition the signal. The maternal ECG R-peaks have been detected based on thresholding, first order Gaussian differentiation and zero cross detection on pre-processed signal. Having identified R-peaks and pre-processed signal as base, using Maximum Likelihood Estimation, one beat including QRS complex morphology of maternal ECG (mECG) has been constructed. Extraction of maternal ECG from abdECG is done based on the constructed beat, R-peak locations and its corresponding QRS complex of abdECG. Extracted mECG has been cancelled from abdECG. This results in foetal ECG with residual noise. The noise has been reduced by Polynomial Approximation and Total Variation (PATV) to improve SNR. This approach ensures no loss of partially or completely overlapped fECG signals due to mECG removal. The algorithm is tested on three database namely daISy (DB_I), Physiobank challenge 2013 (DB_II) and abdominal and direct foetal ECG database (adfecgdb) of Physiobank (DB_III).

RESULTS

The algorithm detected no false positives or false negatives with certain channel for DB_I, DB_II and DB_III which shows that the proposed algorithm can achieve good performance. Overall accuracy and sensitivity of the system is 98.53% and 100% for DB_I. Best accuracy and sensitivity of 97.77% and 98.63% are obtained for DB_II. Best accuracy of 92.41% and sensitivity of 93.8% are obtained for DB_III. Correlation coefficient between actual foetal heart rate (fHR) and estimated fHR of 0.66 for DB_II and 0.59 for DB_III is obtained. The method has obtained overall F1 score of 99.25% for DB_I, 96.04% for DB_II and 94.25% for DB_III. It has obtained a best MSE of fHR and overall MSE of R-R interval which is 10.8bpm² and 2.2 ms for DB_II, 12bpm² and 2.14 ms for DB_III.

CONCLUSION

The results for different public databases show that the proposed method is capable of providing good results. The foetal QRS, R-peaks and R-R intervals have also been obtained in this method. Thus, it gives a significant contribution in the required area of research.

Secondary Imaging Findings Aid in Prenatal Diagnosis and Characterization of Congenital Diaphragmatic Hernia: Role of an Abnormal Orientation of Vascular Structures and Gallbladder Position

OBJECTIVES

To determine whether an abnormal orientation of the abdominal or hepatic vasculature and an abnormal gallbladder position on prenatal ultrasound (US) imaging are associated with intrathoracic liver herniation and postnatal outcomes in cases of congenital diaphragmatic hernia (CDH).

METHODS

Children who underwent prenatal US examinations and postnatal CDH repair at our institution were eligible. Prenatal US images were reviewed, and the orientation of the superior mesenteric artery (SMA) and hepatic veins as well as gallbladder position were recorded. Findings were correlated with prenatal US measurements (lung-to-head ratio and calculated observed-to-expected lung-to-head ratio) and postnatal outcomes, including intrathoracic liver herniation, an extracorporeal membrane oxygenation (ECMO) requirement, and mortality.

RESULTS

A total of 175 patients met inclusion criteria. The SMA was shown in 168 cases and had a cephalad orientation in 95.4% (161 of 168), which was not associated with outcome measures and represented bowel herniation. A cephalad orientation of the hepatic veins was identified in 52.6% (90 of 171) and was associated with intrathoracic liver herniation, an ECMO requirement, and mortality (P < .01). In right-sided CDH, the gallbladder was intrathoracic in 91.3% (21 of 23). In left-sided CDH, an abnormal gallbladder position was seen in 51.3% (76/152) and was associated with intrathoracic liver herniation, an ECMO requirement, mortality, and lower lung-to-head ratio and observed-to-expected lung-to-head ratio values. When combined, abnormal hepatic vein and gallbladder positions showed good sensitivity and specificity in predicting intrathoracic liver herniation (area under the curve, 0.93).

CONCLUSIONS

Abnormal SMA, hepatic vein, and gallbladder positions can be used to improve prenatal characterization of CDH. Accurate depiction of these structures on prenatal US images may aid in patient counseling and postnatal management.

Using fetal abdominal circumference growth velocity in the prediction of adverse outcome in near-term small-for-gestational-age fetuses

OBJECTIVE

To investigate whether abdominal circumference growth velocity (ACGV) improves the prediction of perinatal outcome in small-for-gestational-age (SGA) fetuses beyond that afforded by estimated fetal weight (EFW) and cerebroplacental ratio (CPR).

METHODS

A cohort of 235 singleton SGA fetuses at 36-38 weeks' gestation was examined. ACGV, EFW and CPR centiles were calculated. ACGV centile was determined using data from a large database of 19-21- and 36-38-week scans in an unselected population. Binary variables of ACGV < 10^th , EFW < 3^rd and CPR < 5^th centiles were defined as abnormal. Two composite adverse outcomes (CAO) were explored: CAO-1 defined as at least one of umbilical artery pH < 7.10, 5-min Apgar score < 7 or neonatal unit admission, and CAO-2 that included in addition hypoglycemia, intrapartum fetal distress and perinatal death. Univariate and multivariate logistic regression analyses were performed to analyze the relationship between the three risk factors and their predictive value for CAO. The change in screening performance afforded by adding ACGV to EFW and CPR was assessed and receiver-operating characteristics (ROC) curves were calculated.

RESULTS

ACGV < 10^th centile was an independent risk factor for CAO. The sensitivity, specificity, positive and negative likelihood ratios of a predictive model based on EFW < 3^rd centile and CPR < 5^th centile were, respectively, 51%, 70%, 1.71 and 0.69 for CAO-1 and 41%, 70%, 1.39 and 0.83 for CAO-2. After addition of ACGV < 10^th centile to the model, the respective values were 82%, 46%, 1.54 and 0.38 for CAO-1 and 71%, 47%, 1.34 and 0.62 for CAO-2. Using continuous variables, the areas under the ROC curves improved marginally from 0.669 (95% CI, 0.604-0.729) to 0.741 (95% CI, 0.677-0.798) for CAO-1 and from 0.646 (95% CI, 0.580-0.707) to 0.700 (95% CI, 0.633-0.759) for CAO-2 after addition of ACGV to the model.

CONCLUSIONS

ACGV is a risk factor for adverse neonatal outcome that is independent of EFW and of CPR, although any improvement in the prediction of adverse outcome is not statistically significant. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Quality control of ultrasound for fetal biometry: results from the INTERGROWTH-21st Project

OBJECTIVE

To assess a comprehensive package of ultrasound quality control in the Fetal Growth Longitudinal Study of the INTERGROWTH-21^st Project, a large multicenter study of fetal growth.

METHODS

Quality control (QC) measures were performed for 20 313 ultrasound scan images obtained prospectively from 4321 fetuses at 14-41 weeks' gestation in eight geographical locations. At the time of each ultrasound examination, three fetal biometric variables (head circumference (HC), abdominal circumference (AC) and femur length (FL)) were measured in triplicate on separately generated images. All measurements were taken in a blinded fashion. QC had two elements: (1) qualitative QC: visual assessment by sonographers at each study site of their images based on specific criteria, with 10% of images being re-assessed at the Oxford-based Ultrasound Quality Unit (compared using an adjusted kappa statistic); and (2) quantitative QC: assessment of measurement data by comparing the first, second and third measurements (intraobserver variability), remeasurement of caliper replacement in 10% (interobserver variability), both by Bland-Altman plots and plotting frequency histograms of the SD of triplicate measurements and assessing how many were above or below 2 SD of the expected distribution. The system allowed the sonographers' performances to be monitored regularly.

RESULTS

A high level of agreement between self- and external scoring was demonstrated for all measurements (κ = 0.99 (95% CI, 0.98-0.99) for HC, 0.98 (95% CI, 0.97-0.99) for AC and 0.96 (95% CI, 0.95-0.98) for FL). Intraobserver 95% limits of agreement (LoA) of ultrasound measures for HC, AC and FL were ± 3.3%, ± 5.6% and ± 6.2%, respectively; the corresponding values for interobserver LoA were ± 4.4%, ± 6.0% and ± 5.6%. The SD distribution of triplicate measurements for all biometric variables showed excessive variability for three of 31 sonographers, allowing prompt identification and retraining.

CONCLUSIONS

Qualitative and quantitative QC monitoring was feasible and highly reproducible in a large multicenter research study, which facilitated the production of high-quality ultrasound images. We recommend that the QC system we developed is implemented in future research studies and clinical practice. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Estimating Gestational Age With Sonography: Regression-Derived Formula Versus the Fetal Biometric Average

OBJECTIVES

To compare the accuracy of a new regression-derived formula developed from the National Fetal Growth Studies data to the common alternative method that uses the average of the gestational ages (GAs) calculated for each fetal biometric measurement (biparietal diameter, head circumference, abdominal circumference, and femur length).

METHODS

This retrospective cross-sectional study identified nonanomalous singleton pregnancies that had a crown-rump length plus at least 1 additional sonographic examination with complete fetal biometric measurements. With the use of the crown-rump length to establish the referent estimated date of delivery, each method's (National Institute of Child Health and Human Development regression versus Hadlock average [Radiology 1984; 152:497-501]), error at every examination was computed. Error, defined as the difference between the crown-rump length-derived GA and each method's predicted GA (weeks), was compared in 3 GA intervals: 1 (14 weeks-20 weeks 6 days), 2 (21 weeks-28 weeks 6 days), and 3 (≥29 weeks). In addition, the proportion of each method's examinations that had errors outside prespecified (±) day ranges was computed by using odds ratios.

RESULTS

A total of 16,904 sonograms were identified. The overall and prespecified GA range subset mean errors were significantly smaller for the regression compared to the average (P < .01), and the regression had significantly lower odds of observing examinations outside the specified range of error in GA intervals 2 (odds ratio, 1.15; 95% confidence interval, 1.01-1.31) and 3 (odds ratio, 1.24; 95% confidence interval, 1.17-1.32) than the average method.

CONCLUSIONS

In a contemporary unselected population of women dated by a crown-rump length-derived GA, the National Institute of Child Health and Human Development regression formula produced fewer estimates outside a prespecified margin of error than the commonly used Hadlock average; the differences were most pronounced for GA estimates at 29 weeks and later.

Detection of Intrauterine Growth Retardation by Ultrasound: Preliminary Communication

In this study, ultrasonic measurements of the fetal head area and abdominal area were obtained in 1200 patients with singleton pregnancies. The results from the 434 who have delivered, indicate that a large proportion of growth-retarded infants cannot be identified by a single late ultrasonic measurement of either area, at 32–34 weeks gestation, as has been previously suggested.

Prediction of cesarean delivery in the term nulliparous woman: results from the prospective, multicenter Genesis study

BACKGROUND

In contemporary practice many nulliparous women require intervention during childbirth such as operative vaginal delivery or cesarean delivery (CD). Despite the knowledge that the increasing rate of CD is associated with increasing maternal age, obesity and larger infant birthweight, we lack a reliable method to predict the requirement for such potentially hazardous obstetric procedures during labor and delivery. This issue is important, as there are greater rates of morbidity and mortality associated with unplanned CD performed in labor compared with scheduled CDs. A prediction algorithm to identify women at risk of an unplanned CD could help reduced labor associated morbidity.

OBJECTIVE

In this primary analysis of the Genesis study, our objective was to prospectively assess the use of prenatally determined, maternal and fetal, anthropomorphic, clinical, and ultrasound features to develop a predictive tool for unplanned CD in the term nulliparous woman, before the onset of labor.

MATERIALS AND METHODS

The Genesis study recruited 2336 nulliparous women with a vertex presentation between 39+0 and 40+6 weeks' gestation in a prospective multicenter national study to examine predictors of CD. At recruitment, a detailed clinical evaluation and ultrasound assessment were performed. To reduce bias from knowledge of these data potentially influencing mode of delivery, women, midwives, and obstetricians were blinded to the ultrasound data. All hypothetical prenatal risk factors for unplanned CD were assessed as a composite. Multiple logistic regression analysis and mathematical modeling was used to develop a risk evaluation tool for CD in nulliparous women. Continuous predictors were standardized using z scores.

RESULTS

From a total enrolled cohort of 2336 nulliparous participants, 491 (21%) had an unplanned CD. Five parameters were determined to be the best combined predictors of CD. These were advancing maternal age (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.09 to 1.34), shorter maternal height (OR, 1.72; 95% CI, 1.52 to 1.93), increasing body mass index (OR, 1.29; 95% CI, 1.17 to 1.43), larger fetal abdominal circumference (OR, 1.23; 95% CI, 1.1 to 1.38), and larger fetal head circumference (OR, 1.27; 95% CI, 1.14 to 1.42). A nomogram was developed to provide an individualized risk assessment to predict CD in clinical practice, with excellent calibration and discriminative ability (Kolmogorov-Smirnov, D statistic, 0.29; 95% CI, 0.28 to 0.30) with a misclassification rate of 0.21 (95% CI, 0.19 to 0.25).

CONCLUSION

Five parameters (maternal age, body mass index, height, fetal abdominal circumference, and fetal head circumference) can, in combination, be used to better determine the overall risk of CD in nulliparous women at term. A risk score can be used to inform women of their individualized probability of CD. This risk tool may be useful for reassuring most women regarding their likely success at achieving an uncomplicated vaginal delivery as well as selecting those patients with such a high risk for CD that they should avoid a trial of labor. Such a risk tool has the potential to greatly improve planning hospital service needs and minimizing patient risk.

Fetal size monitoring and birth-weight prediction: a new population-based approach

OBJECTIVE

To develop a complete, population-based system for ultrasound-based fetal size monitoring and birth-weight prediction for use in the second and third trimesters of pregnancy.

METHODS

Using 31 516 ultrasound examinations from a population-based Norwegian clinical database, we constructed fetal size charts for biparietal diameter, femur length and abdominal circumference from 24 to 42 weeks' gestation. A reference curve of median birth weight for gestational age was estimated using 45 037 birth weights. We determined how individual deviations from the expected ultrasound measures predicted individual percentage deviations from expected birth weight. The predictive quality was assessed by explained variance of birth weight and receiver-operating characteristics curves for prediction of small-for-gestational age. A curve for intrauterine estimated fetal weight was constructed. Charts were smoothed using the gamlss non-linear regression method.

RESULTS

The population-based approach, using bias-free ultrasound gestational age, produces stable estimates of size-for-age and weight-for-age curves in the range 24-42 weeks' gestation. There is a close correspondence between percentage deviations and percentiles of birth weight by gestational age, making it easy to convert between the two. The variance of birth weight that can be 'explained' by ultrasound increases from 8% at 20 weeks up to 67% around term. Intrauterine estimated fetal weight is 0-106 g higher than median birth weight in the preterm period.

CONCLUSIONS

The new population-based birth-weight prediction model provides a simple summary measure, the 'percentage birth-weight deviation', to be used for fetal size monitoring throughout the third trimester. Predictive quality of the model can be measured directly from the population data. The model computes both median observed birth weight and intrauterine estimated fetal weight. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

[Fetal MRI practices in a university prenatal center]

OBJECTIVES

Fetal MRI is a third intention examination to prenatal diagnosis. If its diagnostic value is well known in many pathologies, its place in the management of pregnancies remains unclear.

METHODS

We collected retrospectively demographical, radiological (fetal MRI indications, fetal anatomical region and diagnostic information provided by fetal MRI) and obstetrical data of pregnant patients in university prenatal center during a 5 years' period.

RESULTS

Among 2439 patients of the prenatal center, 196 (8%) patients with fetal MRI were included. The main anatomical regions studied were the brain (n=132, 67%), the thorax (n=31, 16%) and the abdomen (n=25, 13%). No cardiac fetal MRI was performed. Ninety-five percent of fetal MRI was consecutively of an ultrasound sign. Fetal brain MRI was abnormal in 65% of cases, the thoracic and abdominopelvic MRI in 81.5%. The ultrasound diagnosis was unchanged in 42%, completed in 50% and redirected in 8% of cases. A termination of pregnancy was deemed admissible in 31% of patients with MRI versus 21% in patients without MRI (P=0.001).

CONCLUSION

Fetal MRI requires selective indications and provides additional diagnostic information with important implications for the future of the pregnancy, particularly in case of severe and incurable pathologies. Our results could be useful as a reference basis for the comparison with others prenatal center practices.

Bedside diagnosis of two major clinical phenotypes of hypertensive disorders of pregnancy

OBJECTIVE

To investigate the hypothesis that fetal abdominal circumference (AC) and uterine artery (UtA) Doppler pulsatility index (PI) could be used to select two homogeneous subgroups of women affected by hypertensive disorders of pregnancy (HDP), characterized by the coexistence of maternal hypertension with and without intrauterine growth restriction (IUGR).

METHODS

This was a multicenter retrospective study of cases affected by HDP in whom fetal AC and UtA-PI had been measured at admission to fetomaternal medicine units. Maternal characteristics, pregnancy complications and outcome were recorded. These data allowed us to model the characteristics of fetal growth in cases affected by HDP, and to design composite indicators of risk factors for maternal metabolic syndrome and of severity for maternal functional organ damage.

RESULTS

Measurements of fetal AC and UtA-PI allowed us to define a group of HDP cases with appropriate-for-gestational-age (AGA) fetuses (HDP-AGA), diagnosed by normal fetal AC and UtA-PI (n = 205), and a group of HDP cases with IUGR fetuses (HDP-IUGR), diagnosed by fetal AC < 5(th) centile and UtA-PI > 95(th) centile (n = 124). Curves fitted to the birth weights of these two groups were significantly different, but gestational age at admission for HDP (< 34 or ≥ 34 weeks) did not show an independent association with birth weight. When birth weight was expressed as a Z-score with respect to local reference charts, the average corresponded to the 6(th) and 48(th) centiles, respectively. The occurrence of HDP-AGA (as compared with HDP-IUGR) was significantly associated with risk factors for maternal metabolic syndrome (odds ratio, 2.79 (95% CI, 1.57-4.97)), independent of gestational age. The same risk factors yielded non-significant odds ratios for the development of late-onset (vs early-onset) HDP. Women with HDP-IUGR had worse clinical outcomes.

CONCLUSIONS

This study provides new information based on simple prenatal bedside examinations that might help to differentiate HDP-IUGR from HDP-AGA fetuses. These groups are associated with different fetal growth patterns and risk factors, independent of gestational age at onset of the disease. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

[Is the stomach a main landmark on the abdominal circumference? Audit of 3 operators]

OBJECTIVES

The fetal weight estimation depends largely on the accuracy of abdominal circumference. The quality criteria are standardized to minimize variability and include visualization of the stomach. The objective of this study is to investigate the presence or absence of the stomach on the abdominal circumference for 3 different operators.

MATERIAL AND METHODS

We conducted re-reading of 204 ultrasound images in the second and third trimester of pregnancy, performed by three operators, at the maternity Port Royal in Paris in 2013. On these images, the presence of the stomach was sought and other quality criteria were verified.

RESULTS

Among the 204 images, 166 included the stomach (81%). When studying for each of the three operators, there were 79%, 72% and 98% of the stomach into the abdominal circumference, a significant difference between operators (P=0.0029). Regarding the secondary criteria, the quality criteria found most often were the calipers and well placed ellipse (89%).

CONCLUSION

According to the previous studies, the stomach seems to be a reference to search. Our study shows variability depending on the different operators. If a hierarchy of quality criteria is to be considered, the stomach does not seem to be the first criterion to search.

Systematic examination of the fetal abdominal precordial veins: a cohort study

OBJECTIVES

Examination of the fetal venous system is a necessary part of complete fetal organ scanning to confirm landmark anatomy, such as the ductus venosus and course of the umbilical veins, and, whenever cardiovascular anomalies are identified, to exclude associated anomalous development of the fetal veins. We aimed to develop a protocol for systematic examination of the fetal venous system during midtrimester targeted organ scanning.

METHODS

We included low-risk women with a singleton fetus presenting between January 2011 and June 2013 to our center for routine midtrimester (20-24 weeks) targeted organ scanning. Imaging of the venous system was added to the booked scan and comprised two-dimensional color Doppler scanning of the fetal abdomen in three discrete planes, two transverse and one longitudinal. The more caudal plane was obtained in a ventral or lateral transverse abdominal plane to image the umbilical vein, left portal vein, portal sinus, anterior right portal vein, posterior right portal vein, main portal vein and splenic vein and artery. Moving cephalad, a ventral or lateral transverse plane was obtained to image the right, middle and left hepatic veins and inferior vena cava (IVC). Finally, a longitudinal anteroposterior plane showed the umbilical vein, ductus venosus, IVC and left hepatic vein. In some cases the pulsed Doppler waveform of a given target vessel was also examined. Three-dimensional/4D ultrasound was applied as necessary, when anomalous cases were encountered.

RESULTS

We examined 1810 women. Their body mass index ranged from 19 to 40 (mean, 24.7). In 38 (2.1%) women, the target anatomy was not visualized satisfactorily owing to maternal body habitus. A T-shaped configuration of the portal system vessels was observed in 63% of cases, an X-shaped configuration in 25% and an H-shaped configuration in 12%. During the study period, 24 congenital anomalies of the precordial venous system were diagnosed: nine cases of persistent right umbilical vein, seven of agenesis of the ductus venosus, five of anomalous portal venous drainage and three of interrupted IVC with azygos continuation.

CONCLUSIONS

Examination of the fetal venous system is feasible with the application of three abdominal planes. While a venous system scan is not practicable as part of a screening-level examination, mastery of the normal anatomy is an essential part of the professional knowledge base, in order to provide ready and complete scanning of the system in cases of suspected anomalies or disordered cardiac function.

Biparietal/transverse abdominal diameter ratio ≤ 1: potential marker for open spina bifida at 11-13-week scan

OBJECTIVE

In the first trimester of pregnancy, a biparietal diameter (BPD) below the 5(th) percentile is a simple marker that enables the prenatal detection of half of all cases of open spina bifida. We hypothesized that relating the BPD measurement to the transverse abdominal diameter (TAD) might be another simple and effective screening method. In this study we assessed the performance of using the BPD/TAD ratio during the first trimester of pregnancy in screening for open spina bifida.

METHODS

A total of 20,551 first-trimester ultrasound scans (11-13 weeks' gestation), performed between 2000 and 2013, were analyzed retrospectively; there were 26 cases of open spina bifida and 17,665 unaffected pregnancies with a crown-rump length of 45-84 mm and a record of both BPD and TAD measurements.

RESULTS

The mean (± SD) BPD/TAD ratio was 1.00 ± 0.06 for fetuses with spina bifida and 1.13 ± 0.06 for those without (P < 0.0001). A BPD ≤ 5(th) percentile enabled the prenatal detection of 46.2% of spina bifida cases, while a BPD/TAD ratio of ≤ 1.00 detected 69.2%. If we considered cases in which either BPD was ≤ 5(th) percentile or BPD/TAD ratio was ≤ 1, we identified 76.9% of cases. In the latter case, the false-positive rate was 5.1%, while that for using a combination of both BPD ≤ 5th percentile and BPD/TAD ratio ≤ 1 was 0.6%, with a sensitivity of 38.5%. The positive predictive value of using a combination of BPD ≤ 5th percentile and BPD/TAD ratio ≤ 1 for detecting spina bifida was 8.5%.

CONCLUSIONS

Between 11 and 13 weeks' gestation, relating BPD to TAD improves considerably the diagnostic performance of using BPD measurement alone in screening for open spina bifida. Screening using this marker is simple and applicable to a large population.

Standard plane localization in ultrasound by radial component model and selective search

Acquisition of the standard plane is crucial for medical ultrasound diagnosis. However, this process requires substantial experience and a thorough knowledge of human anatomy. Therefore it is very challenging for novices and even time consuming for experienced examiners. We proposed a hierarchical, supervised learning framework for automatically detecting the standard plane from consecutive 2-D ultrasound images. We tested this technique by developing a system that localizes the fetal abdominal standard plane from ultrasound video by detecting three key anatomical structures: the stomach bubble, umbilical vein and spine. We first proposed a novel radial component-based model to describe the geometric constraints of these key anatomical structures. We then introduced a novel selective search method which exploits the vessel probability algorithm to produce probable locations for the spine and umbilical vein. Next, using component classifiers trained by random forests, we detected the key anatomical structures at their probable locations within the regions constrained by the radial component-based model. Finally, a second-level classifier combined the results from the component detection to identify an ultrasound image as either a "fetal abdominal standard plane" or a "non- fetal abdominal standard plane." Experimental results on 223 fetal abdomen videos showed that the detection accuracy of our method was as high as 85.6% and significantly outperformed both the full abdomen and the separate anatomy detection methods without geometric constraints. The experimental results demonstrated that our system shows great promise for application to clinical practice.

International standards for fetal growth based on serial ultrasound measurements: the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project

BACKGROUND

In 2006, WHO produced international growth standards for infants and children up to age 5 years on the basis of recommendations from a WHO expert committee. Using the same methods and conceptual approach, the Fetal Growth Longitudinal Study (FGLS), part of the INTERGROWTH-21(st) Project, aimed to develop international growth and size standards for fetuses.

METHODS

The multicentre, population-based FGLS assessed fetal growth in geographically defined urban populations in eight countries, in which most of the health and nutritional needs of mothers were met and adequate antenatal care was provided. We used ultrasound to take fetal anthropometric measurements prospectively from 14 weeks and 0 days of gestation until birth in a cohort of women with adequate health and nutritional status who were at low risk of intrauterine growth restriction. All women had a reliable estimate of gestational age confirmed by ultrasound measurement of fetal crown-rump length in the first trimester. The five primary ultrasound measures of fetal growth--head circumference, biparietal diameter, occipitofrontal diameter, abdominal circumference, and femur length--were obtained every 5 weeks (within 1 week either side) from 14 weeks to 42 weeks of gestation. The best fitting curves for the five measures were selected using second-degree fractional polynomials and further modelled in a multilevel framework to account for the longitudinal design of the study.

FINDINGS

We screened 13,108 women commencing antenatal care at less than 14 weeks and 0 days of gestation, of whom 4607 (35%) were eligible. 4321 (94%) eligible women had pregnancies without major complications and delivered live singletons without congenital malformations (the analysis population). We documented very low maternal and perinatal mortality and morbidity, confirming that the participants were at low risk of adverse outcomes. For each of the five fetal growth measures, the mean differences between the observed and smoothed centiles for the 3rd, 50th, and 97th centiles, respectively, were small: 2·25 mm (SD 3·0), 0·02 mm (3·0), and -2·69 mm (3·2) for head circumference; 0·83 mm (0·9), -0·05 mm (0·8), and -0·84 mm (1·0) for biparietal diameter; 0·63 mm (1·2), 0·04 mm (1·1), and -1·05 mm (1·3) for occipitofrontal diameter; 2·99 mm (3·1), 0·25 mm (3·2), and -4·22 mm (3·7) for abdominal circumference; and 0·62 mm (0·8), 0·03 mm (0·8), and -0·65 mm (0·8) for femur length. We calculated the 3rd, 5th 10th, 50th, 90th, 95th and 97th centile curves according to gestational age for these ultrasound measures, representing the international standards for fetal growth.

INTERPRETATION

We recommend these international fetal growth standards for the clinical interpretation of routinely taken ultrasound measurements and for comparisons across populations.

FUNDING

Bill & Melinda Gates Foundation.

Outcome of first-trimester fetal abdominal cysts: cohort study and review of the literature

OBJECTIVES

The aims of this study were to ascertain the outcome of fetuses with an abdominal cyst detected at 11-14 weeks' gestation in our unit and to undertake a review of cases reported in the literature.

METHODS

This was a retrospective study that included all fetuses found to have an abdominal cyst on ultrasound examination at 11-14 weeks, identified over a 14-year period. Pregnancy management and outcome were ascertained from maternal and neonatal records. We also performed a review of the literature using a systematic search strategy, to identify the outcome of similar cases and propose a management algorithm.

RESULTS

Fourteen cases were identified during the study period, of which four had associated abnormalities. Of the 10 isolated cases, the cyst had resolved at follow-up scan in eight (80.0%), one fetus died in utero at 15 weeks' gestation and the other case underwent surgery for a choledochal cyst 9 weeks after birth. An additional 19 cases were reported in the literature. In eight fetuses there were associated structural abnormalities, of which four had a diagnosis of anorectal malformation after birth. In two of these four, the cyst resolved in the second trimester. Of those cases with an isolated cyst (n = 11), the cyst resolved in seven (63.6%). The remainder were variably diagnosed as hepatic cyst, ileal duplication or choledochal cyst.

CONCLUSION

Fetal abdominal cysts at 11-14 weeks' gestation are rare. They constitute an isolated finding in the majority of cases and are usually associated with a good perinatal outcome. In view of the reported association with anorectal and other gastrointestinal malformations, perinatal assessment is recommended, even if the cyst resolves during pregnancy.

Ectodermal Wnt signaling regulates abdominal myogenesis during ventral body wall development

Defects of the ventral body wall are prevalent birth anomalies marked by deficiencies in body wall closure, hypoplasia of the abdominal musculature and multiple malformations across a gamut of organs. However, the mechanisms underlying ventral body wall defects remain elusive. Here, we investigated the role of Wnt signaling in ventral body wall development by inactivating Wls or β-catenin in murine abdominal ectoderm. The loss of Wls in the ventral epithelium, which blocks the secretion of Wnt proteins, resulted in dysgenesis of ventral musculature and genito-urinary tract during embryonic development. Molecular analyses revealed that the dermis and myogenic differentiation in the underlying mesenchymal progenitor cells was perturbed by the loss of ectodermal Wls. The activity of the Wnt-Pitx2 axis was impaired in the ventral mesenchyme of the mutant body wall, which partially accounted for the defects in ventral musculature formation. In contrast, epithelial depletion of β-catenin or Wnt5a did not resemble the body wall defects in the ectodermal Wls mutant. These findings indicate that ectodermal Wnt signaling instructs the underlying mesodermal specification and abdominal musculature formation during ventral body wall development, adding evidence to the theory that ectoderm-mesenchyme signaling is a potential unifying mechanism for the origin of ventral body wall defects.

Evaluation of fetal anthropometric measures to predict the risk for shoulder dystocia

OBJECTIVE

To evaluate the quality of anthropometric measures to improve the prediction of shoulder dystocia by combining different sonographic biometric parameters.

METHODS

This was a retrospective cohort study of 12,794 vaginal deliveries with complete sonographic biometry data obtained within 7 days before delivery. Receiver-operating characteristics (ROC) curves of various combinations of the biometric parameters, namely, biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference, abdominal diameter (AD), abdominal circumference (AC) and femur length were analyzed. The influences of independent risk factors were calculated and their combination used in a predictive model.

RESULTS

The incidence of shoulder dystocia was 1.14%. Different combinations of sonographic parameters showed comparable ROC curves without advantage for a particular combination. The difference between AD and BPD (AD - BPD) (area under the curve (AUC) = 0.704) revealed a significant increase in risk (odds ratio (OR) 7.6 (95% CI 4.2-13.9), sensitivity 8.2%, specificity 98.8%) at a suggested cut-off ≥ 2.6 cm. However, the positive predictive value (PPV) was low (7.5%). The AC as a single parameter (AUC = 0.732) with a cut-off ≥ 35 cm performed worse (OR 4.6 (95% CI 3.3-6.5), PPV 2.6%). BPD/OFD (a surrogate for fetal cranial shape) was not significantly different between those with and those without shoulder dystocia. The combination of estimated fetal weight, maternal diabetes, gender and AD - BPD provided a reasonable estimate of the individual risk.

CONCLUSION

Sonographic fetal anthropometric measures appear not to be a useful tool to screen for the risk of shoulder dystocia due to a low PPV. However, AD - BPD appears to be a relevant risk factor. While risk stratification including different known risk factors may aid in counseling, shoulder dystocia cannot effectively be predicted.

Hunchback is required for abdominal identity suppression and germband growth in the parthenogenetic embryogenesis of the pea aphid, Acyrthosiphon pisum

Aphid, a short germband insect, displays an embryogenesis different from that of long germband insect species. Furthermore, the development of its parthenogenetic and viviparous embryo is different from that of the embryo resulting from sexual reproduction. To better understand the genetic regulation of this type of embryogenesis, the functions of hunchback in asexual Acyrthosiphon pisum were investigated by parental RNAi. Microinjection of Aphb double-stranded RNA yielded several defective phenotypes. Quantitative real-time PCR analysis revealed that these defects resulted from reduction of Aphb mRNA level in injected aphids. All these results suggested that the hb gene in parthenogenetic and viviparous Acyrthosiphon pisum was involved in abdominal identity suppression and germband growth as its homologue does in sexual insects.

Upper abdominal cysts in first trimester fetuses

Cystic abdominal structures in first trimester fetuses are rare. In order to elucidate the clinical significance of first trimester abdominal cysts, we present three cases of the ultrasonographic detection of upper abdominal cysts in first trimester fetuses with spontaneous regression until birth. Cysts with maximum diameters of 20, 15 and 21 mm were diagnosed in the first scan at 12 + 3 weeks of gestation and two times at 13 + 0 weeks of gestation, respectively. They had echogenic walls, a longish shape and were all located in the upper part of the abdomen. Further anomalies, relevant maternal infections, the most frequent cystic fibrosis mutations and fetal chromosomal abnormalities were excluded. In all three cases follow-up scans showed similar characteristics: The relatively large intraabdominal cyst resolved during the early second trimester. A hyperdense structure of up to 24 mm close to the liver capsule was the sole prenatally detectable remnant. During the first months after birth, development of all three children was normal. Pediatric ultrasound examination reported subcapsular liver calcifications. In conclusion, these cases demonstrate that first trimester upper abdominal cysts with spontaneous resolution until birth are associated with a favorable outcome, if infections and additional anatomical or chromosomal anomalies are ruled out. Nevertheless, one should be aware that postnatal gastrointestinal complications have been described in a few cases, even if the cyst had resolved spontaneously in utero.

Influence of fetal and parental factors on intrauterine growth measurements: results of the EDEN mother-child cohort

OBJECTIVE

In small-for-gestational-age neonates, parental and fetal characteristics can be used to distinguish between constitutionally small size and growth restriction, which is associated with a higher risk of morbidity and mortality. The aim of this study was to quantify relationships of parental and fetal characteristics with fetal ultrasound measurements.

METHODS

The EDEN mother-child cohort included 2002 pregnant women with singleton pregnancies attending one of two university hospitals. Data from two routine ultrasound examinations for fetal biometry were recorded, at 20-25 and 30-35 weeks of gestation. Biparietal diameter (BPD), head circumference (HC), femur length (FL), abdominal circumference (AC) and estimated fetal weight (EFW) were studied as a function of prepregnancy maternal body mass index (BMI), maternal height, paternal height, fetal sex and gestational age.

RESULTS

Data were obtained at the first scan from 1833 women and at the second scan from 1752 women. Parental anthropometric characteristics were significantly associated with ultrasound measurements at both scans. Maternal BMI was more strongly associated with AC and EFW, whereas both maternal and paternal height were more strongly associated with FL. An association was also found between fetal sex and all ultrasound measurements other than FL.

CONCLUSION

Maternal and paternal anthropometric characteristics are significantly associated with ultrasound measurements in mid to late pregnancy. These relationships provide support for the use of these characteristics in ultrasound fetal size reference charts.

Umbilical artery pulsatility index and fetal abdominal circumference in isolated gastroschisis

OBJECTIVES

To investigate changes in abdominal circumference (AC) and umbilical artery pulsatility index (UA-PI) with gestation in fetuses with isolated gastroschisis, and to determine whether a relationship exists between UA-PI and fetal AC.

METHODS

Data from 58 pregnancies with isolated gastroschisis diagnosed at between 24 and 36 weeks' gestation were included in the study. Z-scores were calculated with respect to expected UA-PI values in normal pregnancies after log-transformation. AC-Z-scores were calculated with respect to expected size in normal pregnancies according to a standard chart. Functional linear discriminant analysis (FLDA) was applied to generate 50(th), 5(th) and 95(th) percentile curves for changes in both AC and UA-PI with gestational age in fetuses with gastroschisis. These curves were compared with the standard curves, as were the means. UA-PI was also plotted against AC. For this relationship, a robust Spearman correlation coefficient was obtained with FLDA.

RESULTS

In fetuses with gastroschisis, there was a highly significant negative correlation between UA-PI and AC, normalized for gestation using Z-scores (median correlation coefficient, - 0.289; median P = 0.000023). Moreover, compared with standard curves AC was lower and UA-PI higher in the gestational-age range studied. Both the AC and UA-PI curves showed a significantly different rate of change with gestation compared with the normal ranges. The mean values for fetuses with gastroschisis compared with the standard AC and UA-PI range curves were significantly different for AC throughout gestation, and for UA-PI from 32 weeks' gestation.

CONCLUSIONS

In fetal gastroschisis, it is well known that AC tends to be smaller, though UA-PI has not been reported to be abnormal in any consistent way. There is a clear relationship between the fetus's AC for gestation and UA-PI, which is not the case for normally grown fetuses. The data suggest that the growth restriction seen in gastroschisis may be explained by hypoxia, and not simply by the classical explanation of extra-abdominal displacement of the abdominal viscera.

Embryonic development and expression analysis of Distal-less in Caprella scaura (Crustacea, Amphipoda, Caprellidea)

The Caprellidea generally possess rudimentary abdomens and degenerated third and fourth pereopods. Previous molecular phylogenetic studies support the concept that their unique body plan is derived from a gammarid-like body plan from which the abdomen or third and fourth pereopods have been lost in the Caprellidea. To understand the developmental and genetic mechanisms for the morphological evolution of the Caprellidea, we observed the embryonic development of Caprella scaura. Although in the early embryonic stage limb buds appeared in all of the pereonites, we found that elongation of the limb buds did not occur in the third and fourth pereonites; instead, only oval projections (possibly primordial gills) were observed. We next examined the gene expression of Distal-less (Dll) by in situ hybridization and found that Dll was not expressed in the third and fourth pereonites. This suggests that the suppression of Dll expression is responsible for the reduction of Caprellidea pereopods.

Prediction of fetal macrosomia: effect of sonographic fetal weight-estimation model and threshold used

OBJECTIVE

To compare the accuracy of 21 sonographic fetal weight-estimation models and abdominal circumference (AC) as a single measure for the prediction of fetal macrosomia (> 4000 g) using either fixed or optimal model-specific thresholds.

METHODS

A total of 4765 sonographic weight estimations performed within 3 days prior to delivery were analyzed. The predictive accuracy of 21 published sonographic fetal weight-estimation models was calculated using three different thresholds: a fixed threshold of 4000 g; a model-specific threshold obtained from the inflexion point of the receiver-operating characteristics (ROC) curve; and a model-specific threshold associated with the highest overall accuracy. Cluster analysis was used to determine whether a certain combination of fetal biometric indices is associated with a higher predictive accuracy than others.

RESULTS

For a fixed threshold of > 4000 g, there was considerable variation among the models in sensitivity (range, 13.6-98.5%) and specificity (range, 63.6-99.8%) for fetal macrosomia. Use of the threshold derived from the inflexion point of the ROC curve decreased the intermodel variation to a minimum (sensitivity, 84.4-91.4%; and specificity, 79.5-86.3%). Even when this optimal model-specific threshold was applied, models based on three to four biometric indices were more accurate than were models based on only two biometric indices or on AC as a single measure (P=0.03).

CONCLUSIONS

Sonographic fetal weight-estimation models based on three to four biometric indices appear to be more accurate than are models based on two indices or on AC as a single measure, for the diagnosis of macrosomia. In these cases, the use of an optimal, model-specific threshold is associated with a higher degree of accuracy than is the uniform use of a fixed threshold of an estimated weight of > 4000 g.

Influence of RNAi knockdown for E-complex genes on the silkworm proleg development

Larvae of many holometabolous insects possess abdominal appendages called prolegs. Lepidoptera larvae have prolegs in the segments A3-A6. Functions of Lepidoptera hox genes on these abdominal appendages development is still a controversial issue. In this article, we report the use of double strand RNA (dsRNA)-mediated interference (RNAi) to dissect the function of some hox genes, specifically E-complex genes Ubx, abd-A, and Abd-B, in the ventral appendage development of the Lepidoptera silkworm, Bombyx mori. We found that Ubx RNAi caused leg identity in A1 segment, abd-A RNAi caused severe defect of abdominal prolegs and Abd-B RNAi allowed proleg identity in more posterior abdominal segments. These results confirm that Lepidoptera hox genes Ubx and Abd-B have evolved the repressing function to ventral appendage development, which is similar to those of Drosophila. However, Lepidoptera abd-A might have been modified distinctively during evolution, and has important roles in directing the development of prolegs.

Regional differences in neural crest morphogenesis

Neural crest cells are pluripotent cells that emerge from the neural epithelium, migrate extensively, and differentiate into numerous derivatives, including neurons, glial cells, pigment cells and connective tissue. Major questions concerning their morphogenesis include: 1) what establishes the pathways of migration and 2) what controls the final destination and differentiation of various neural crest subpopulations. These questions will be addressed in this review. Neural crest cells from the trunk level have been explored most extensively. Studies show that melanoblasts are specified shortly after they depart from the neural tube, and this specification directs their migration into the dorsolateral pathway. We also consider other reports that present strong evidence for ventrally migrating neural crest cells being similarly fate restricted. Cranial neural crest cells have been less analyzed in this regard but the preponderance of evidence indicates that either the cranial neural crest cells are not fate-restricted, or are extremely plastic in their developmental capability and that specification does not control pathfinding. Thus, the guidance mechanisms that control cranial neural crest migration and their behavior vary significantly from the trunk. The vagal neural crest arises at the axial level between the cranial and trunk neural crest and represents a transitional cell population between the head and trunk neural crest. We summarize new data to support this claim. In particular, we show that: 1) the vagal-level neural crest cells exhibit modest developmental bias; 2) there are differences in the migratory behavior between the anterior and the posterior vagal neural crest cells reminiscent of the cranial and the trunk neural crest, respectively; 3) the vagal neural crest cells take the dorsolateral pathway to the pharyngeal arches and the heart, but the ventral pathway to the peripheral nervous system and the gut. However, these pathways are not rigidly specified because of prior fate restriction. Understanding the molecular, cellular and behavioral differences between these three populations of neural crest cells will be of enormous assistance when trying to understand the evolution of the neck.

Proneural and abdominal Hox inputs synergize to promote sensory organ formation in the Drosophila abdomen

The atonal (ato) proneural gene specifies a stereotypic number of sensory organ precursors (SOP) within each body segment of the Drosophila ectoderm. Surprisingly, the broad expression of Ato within the ectoderm results in only a modest increase in SOP formation, suggesting many cells are incompetent to become SOPs. Here, we show that the SOP promoting activity of Ato can be greatly enhanced by three factors: the Senseless (Sens) zinc finger protein, the Abdominal-A (Abd-A) Hox factor, and the epidermal growth factor (EGF) pathway. First, we show that expression of either Ato alone or with Sens induces twice as many SOPs in the abdomen as in the thorax, and do so at the expense of an abdomen-specific cell fate: the larval oenocytes. Second, we demonstrate that Ato stimulates abdominal SOP formation by synergizing with Abd-A to promote EGF ligand (Spitz) secretion and secondary SOP recruitment. However, we also found that Ato and Sens selectively enhance abdominal SOP development in a Spitz-independent manner, suggesting additional genetic interactions between this proneural pathway and Abd-A. Altogether, these experiments reveal that genetic interactions between EGF-signaling, Abd-A, and Sens enhance the SOP-promoting activity of Ato to stimulate region-specific neurogenesis in the Drosophila abdomen.

Three-dimensional ultrasonographic depiction of fetal abdominal blood vessels

OBJECTIVE

The purpose of this study was to identify fetal abdominal vasculature with 3-dimensional (3D) ultrasonography and to describe a systematic method for analysis of volume data sets.

METHODS

Three-dimensional volumes of the fetal abdomen were acquired prospectively in 30 patients between 15 and 34 weeks' gestation with color Doppler, high-definition (HD) flow, power Doppler, and B-flow imaging. All volumes were analyzed offline by 2 examiners separately. The feasibility of identifying the fetal abdominal blood vessels was analyzed. A standardized approach was applied to identify specific vessels by correlating the images with known anatomic landmarks.

RESULTS

The volumes were rotated into an anatomic orientation in the multiplanar mode, and then the vessels were identified in the following order: aorta (30 of 30), celiac trunk (29 of 30), superior mesenteric vein (28 of 30 and 26 of 30 for readers 1 and 2, respectively), superior mesenteric artery (29 of 30), left renal artery (25 of 30 and 26 of 30), right renal artery (27 of 30), common iliac arteries (30 of 30), umbilical arteries (26 of 27), external iliac arteries (20 of 22), umbilical vein (29 of 30), ductus venosus (30 of 30), hepatic vein (29 of 30), right portal vein (29 of 30), inferior vena cava (28 of 30), adrenal artery (2 of 30), hepatic artery (24 of 30 and 23 of 30), splenic artery (24 of 30 and 23 of 30), gastric artery (14 of 30 and 9 of 30), splenic vein (19 of 30 and 15 of 30), and renal vein (1 of 30). A step-by-step systematic approach to identify the abdominal vasculature from the ultrasonographic volume data set was developed.

CONCLUSIONS

Fetal abdominal vessels can be easily visualized when a systematic analysis is performed on 3D data set volumes. Visualization of the vessels was optimal when volumes were acquired with HD flow imaging.

[Accuracy of ultrasound estimated fetal weight performed by OB-Gyn residents at due date]

OBJECTIVES

The aim of this study was to evaluate the accuracy of ultrasound fetal weight prediction at due date and to find parameters that may affect this prediction.

PATIENTS AND METHODS

We retrospectively studied 201 patients at due date in a university hospital in 2006, the fetal weight estimation being performed by Obstetric-gynecology (OB-Gyn). Estimated fetal weight was calculated with the Hadlock's formula, including biparietal diameter, cephalic circumference, abdominal perimeter and femoral length and was compared with birth weight.

RESULTS

The mean birth weight was 3561+/-415 g. The mean absolute weight difference was 261+/-190 g (absolute range: 0 to 1183 g, actual range: -935 to 1183 g). Body mass index>30 kg/m(2) was associated with greater fetal weight inaccuracy (p=0,013). Fetal weight estimation was not influenced by fetal macrosomia, oligoanamnios or maternal weight gain during pregnancy.

DISCUSSION AND CONCLUSION

The sonographic estimated fetal weight and birth weight are correlated with a mean absolute percentage error of 7%. However, clinicians should be aware of the risk of inaccuracy in obese women.

Volumetric (3D) imaging reduces inter- and intraobserver variation of fetal biometry measurements

OBJECTIVE

To compare the inter- and intraobserver variation of fetal biometric measurements utilizing two-dimensional (2D) and three-dimensional (3D) ultrasound imaging.

METHODS

This prospective study, utilizing three pairs of doctors trained in sonography, evaluated singleton pregnancies in the mid-trimester. Measurements of the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL) were taken in duplicate by each doctor using 2D imaging and then again using 3D volume datasets. Each set of paired doctors evaluated 12 patients. Inter- and intraobserver variation were calculated as the SD of the difference between paired measurements performed by the doctor pairs and by the individual doctors, respectively. Bland-Altman plots were used to visually compare measurement bias and agreement by 2D and 3D methods.

RESULTS

Inter- and intraobserver variation for 2D and 3D ultrasound were small. The intraobserver variation of HC, AC and FL was significantly lower for 3D compared with 2D ultrasound. Interobserver variation was not significantly different when measured with 2D and 3D ultrasound, with the exception of FL, which was lower when measured with 3D ultrasound. The Bland-Altman plots showed that in 95% of the measurements, the percentage difference between 2D and 3D ultrasound techniques was within 5.3%, 4.6%, 9.6% and 9.6% for BPD, HC, AC and FL, respectively.

CONCLUSIONS

2D and 3D fetal biometric measurements are reproducible. The use of 3D ultrasound significantly reduces intraobserver variation for HC, AC and FL and reduces interobserver variation for FL.

Sonographic foetal measurements in a cohort of population of Karachi, Pakistan

The purpose of this cross-sectional study was to establish reference intervals for sonographic measurements of foetal parameters in women with normal singleton pregnancies in a cohort of population of Karachi, Pakistan. It was conducted at the Ultrasound Clinic, and Ziauddin Memorial Hospital, Nazimabad, Karachi, from January 2003 to July 2004. The measurements of foetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL) were carried out on commercially available ultrasound machines using a convex probe of 3.5 MHz frequency. Four hundred women were enrolled; 358 women completed the study. Mean +/- SD, reference intervals and 5th and 95th centiles for the foetal parameters were computed. Regression equations calculated were BPD = -0.36 + 0.27 x GA, (R2 = 0.97); HC = -0.96 + 0.05 x GA, (R2 = 0.95); AC = -0.345 + 0.33 x GA, (R2 = 0.95) and for FL = -1.50 + 0.24 x GA, (R2 = 0.97). [GA = gestational age in weeks, R2 = coefficient of determination]. In this cross-sectional study, predominantly of Urdu-speaking "mohajirs" (67.9%) the reference intervals of commonly used foetal parameters for assessing gestational age i.e. BPD, HC, AC and FL, were established. A larger, multi-centered study to encompass the different ethnic groups of the population is required.

Fetal abdominal cysts in the first trimester: prenatal detection and clinical significance

OBJECTIVE

In order to determine the clinical significance of fetal abdominal cysts detected in the first trimester, we reviewed our experience with such cases collected over a 5-year period.

METHODS

Five cases in which a fetal abdominal cyst was detected by ultrasound in the first trimester were identified. Information on the ultrasound findings, antenatal course and perinatal outcome was obtained in all cases.

RESULTS

The abdominal cyst was confirmed by an early second-trimester scan at 14-16 weeks in all cases, at which time no associated anomalies were detected. The standard detailed second-trimester scan at 18-22 weeks demonstrated complete resolution in three cases. These women had an uneventful antenatal course, and normal newborn infants were delivered at term. However, one of these infants had intestinal malrotation, chronic abdominal distension and midgut volvulus requiring surgery at the age of 7 months. Among the remaining two cases in which the abdominal cyst persisted, one required prenatal aspiration at 19 weeks owing to significant enlargement and resolved. The other remained stable in size and was managed conservatively, but the infant required surgery at the age of 7 weeks owing to a choledochal cyst causing intermittent episodes of acholia.

CONCLUSION

Abdominal cysts in early pregnancy often resolve spontaneously or remain small and are usually associated with a good outcome. Nevertheless, as they can also be associated with serious underlying gastrointestinal pathological conditions, close surveillance in the perinatal period is advocated.

Fetal biometry between 20-42 weeks of gestation for Polish population

OBJECTIVE

Ultrasound estimating of fetal weight is one of the most frequent examinations during pregnancy. Hitherto, foreign fetometry curves have mostly been used in Poland as there are no national available reference charts that are based on ultrasound fetal biometry. The aim of the present study was to construct new charts based on ultrasound fetometry reference for Polish population.

STUDY DESIGN

A group of 959 healthy volunteers with uncomplicated singleton pregnancy joined in a cross-sectional study. The study was designed prospectively to evaluate normal reference charts for fetal ultrasound measurements and estimated fetal weight. Four biometric parameters were studied: biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). Estimated fetal weight (EFW) was calculated using Hadlock et al. formula from 1985.

RESULTS

In the course of normal pregnancy an acceleration of growth rate was seen, but with a slight decline at the end of pregnancy. Reference curves for mean, 90th and 95th percentile were constructed for BPD, HC, AC and FL. Estimated fetal weight curves were outlined for both boys and girls.

CONCLUSION

Reference charts for Polish population are similar to foreign curves. Less variation was seen in comparison with national charts based on postnatal weight. Ultrasound method seems to be better than birthweight curves especially in preterm pregnancies. This will improve the diagnosis of a small for gestational age newborn.

Small fetal abdominal circumference in the second trimester and subsequent low maternal plasma glucose after a glucose challenge test is associated with the delivery of a small-for-gestational age neonate

OBJECTIVES

To evaluate the predictive value of a combination of the 1 h 50-g glucose challenge test (GCT) and second-trimester ultrasound measurement of fetal abdominal circumference (AC) in identifying patients who will go on to deliver small-for-gestational age (SGA) neonates. The individual predictive power of these tests has been indicated by previous studies, but this study examines the combined use of these indicators in predicting SGA.

METHODS

This retrospective cohort study included 576 consecutive patients with singleton gestations examined over a 3-year period. Patients' electronic medical records were abstracted to obtain the result of the GCT, the fetal AC measured by ultrasound examination between 18 and 22 weeks' gestation, and the birth weight. SGA and small AC were defined as birth weight or AC < 10(th) percentile for gestational age, according to published nomograms. A low GCT was defined as < 100 mg/dL. P < 0.05 was considered significant.

RESULTS

The prevalence of SGA in the study population was 8.7% (50/576). The frequency of SGA neonates was significantly higher in patients with a low GCT (27/207) in the second trimester than in those with a normal GCT (23/369) (13% vs. 6.2%, P = 0.005). Similarly, the frequency of SGA neonates was higher among patients with fetal AC < 10(th) percentile than among those with a normal fetal AC on second-trimester ultrasound examination (17% vs. 8%, P = 0.08), although this difference did not reach statistical significance. Of interest, among patients with both a small fetal AC and a low GCT the incidence of SGA neonates was 32% (6/19), but there were no SGA neonates among those with a small AC and normal GCT (0/17) (P = 0.014). Among patients with a small fetal AC the sensitivity of using low GCT to predict subsequent delivery of a SGA neonate was 100%, with a specificity of 57%, positive predictive value 32% and negative predictive value 100%.

CONCLUSIONS

Small AC on routine second-trimester anomaly sonogram should trigger a closer evaluation of maternal GCT. If the GCT is also low, more intensive surveillance for the possible development of a SGA infant is warranted.

New charts for ultrasound dating of pregnancy and assessment of fetal growth: longitudinal data from a population-based cohort study

OBJECTIVES

Correct assessment of gestational age and fetal growth is essential for optimal obstetric management. The objectives of this study were, first, to develop charts for ultrasound dating of pregnancy based on crown-rump length and biparietal diameter and, second, to derive reference curves for normal fetal growth based on biparietal diameter, head circumference, transverse cerebellar diameter, abdominal circumference and femur length from 10 weeks of gestational age onwards.

METHODS

A total of 8313 pregnant women were included for analysis in this population-based prospective cohort study. All women had repeated ultrasound assessments to examine fetal growth.

RESULTS

Charts for ultrasound dating of pregnancy, based on crown-rump length and biparietal diameter, were derived. Internal validation with the actual date of delivery showed that ultrasound imaging provided reliable gestational age estimates. Up to 92% of deliveries took place within 37-42 weeks of gestation if gestational age was derived from ultrasound data, compared with 87% based on a reliable last menstrual period. The earlier the ultrasound assessment the more accurate the prediction of date of delivery. After 24 weeks of gestation a reliable last menstrual period provided better estimates of gestational age. Reference curves for normal fetal growth from 10 weeks of gestational age onwards were derived.

CONCLUSIONS

Charts for ultrasound dating of pregnancy and reference curves for fetal biometry are presented. The results indicate that, up to 24 weeks of pregnancy, dating by ultrasound examination provides a better prediction of the date of delivery than does last menstrual period. The earlier the ultrasound assessment in pregnancy, preferably between 10 and 12 weeks, the better the estimate of gestational age.

Fetal biometry in ethnic Chinese: biparietal diameter, head circumference, abdominal circumference and femur length

OBJECTIVES

To construct new reference charts and equations for fetal biometry in the Hong Kong ethnic Chinese population, and to compare them with existing references from different populations.

METHODS

This was a prospective observational study involving 709 women with singleton pregnancies and confirmed gestational age. For the purposes of this study, each woman was scanned once only, between 12 and 40 completed weeks of gestation, and the following fetal biometric measurements were recorded: biparietal diameter, head circumference, abdominal circumference and femur length. For each measurement, regression models were fitted to estimate the mean and SD at each gestational age. For comparison, the fetal biometric measurements of other populations at each gestation were expressed as Z-scores calculated with our reference equations. Results were presented graphically across the different gestational ages to allow visual comparison.

RESULTS

New charts and reference equations are reported in this Hong Kong Chinese population for fetal outer-inner and outer-outer biparietal diameter, head circumference, abdominal circumference and femur length. Equations for dating of pregnancy are presented. Our charts were very similar to those of the Singaporean population for most parameters. The main difference in our fetal biometric measurements compared with those of the UK and French populations was in FL.

CONCLUSIONS

Our new set of reference centiles for fetal biometric measurements and equations for dating of pregnancy in a Hong Kong Chinese population are ready for clinical use and research in appropriate ethnic Chinese groups.

Estimation of fetal weight by measurement of fetal thigh soft-tissue thickness in the late third trimester

OBJECTIVE

The accuracy of current formulae for the sonographic estimation of fetal weight (EFW) is compromised by significant intra- and interobserver variability of biometrical measurements, particularly circumferences. The aim of this study was to assess the reliability of the linear measurement of mid-thigh soft-tissue thickness (STT) and to derive a novel formula for EFW.

METHODS

This was a prospective study involving 388 singleton uncomplicated pregnancies. There were three consecutive phases: (1) to verify the relationship between STT and birth weight, (2) to derive a novel formula for EFW using femur length and STT only, and (3) to test the accuracy of the new equation. Only the 290 patients who delivered within 48 h of measurement were considered for the analysis. A comparison with other formulae was performed.

RESULTS

STT was significantly correlated with both abdominal circumference and birth weight (r(2) = 0.36 and 0.46, respectively; P < 0.001). Both intra- and interobserver variability were satisfactory (0.44 +/- 0.27 and 0.57 +/- 0.35 mm, respectively). The equation for EFW was developed using multiple stepwise regression analysis (EFW = - 1687.47 + (54.1 x femur length) + (76.68 x STT)) and tested prospectively on 69 patients. The new formula yielded results (r = 0.79) that were slightly better in accuracy than two other published equations, and had an absolute mean error of < 15% in 97% of cases.

CONCLUSIONS

Our findings confirm the potential of the linear measurement of mid-thigh STT as a valuable parameter for the sonographic assessment of fetal growth and EFW. Our new equation is apparently at least as reliable as the most widely used formulae for EFW.

Fetal abdominal contour extraction and measurement in ultrasound images

A novel method is developed for the fetal abdominal contour extraction and measurement in ultrasound images. Fetal abdominal circumference (AC) is one of the standardized measurements in the antepartum ultrasound monitoring. Among several standardized measurements, AC is best correlated with fetal growth but is also the most difficult to be accurately measured. To overcome the difficulties in the abdominal contour extraction, the proposed method is a four-step procedure that integrates several image segmentation techniques. The proposed method is able to make the best use of the strength of different segmentation algorithms, while avoiding their deficiencies. An enhanced instantaneous coefficient of variation (ICOV) edge detector is first developed to detect edges of the abdominal contour and alleviate the effects of most speckle noise. Then, the Fuzzy C-Means clustering is employed to distinguish salient edges attributable to the abdominal contour from weak edges due to the other texture. Subsequently, the iterative Hough transform is applied to determine an elliptical contour and obtain an initial estimation of the AC. Finally, the gradient vector field (GVF) snake adapts the initial ellipse to the real edges of the abdominal contour. Quantitative validation of the proposed method on synthetic images under different imaging conditions achieves satisfactory segmentation accuracy (98.78%+/-0.16%). Experiments on 150 clinical images are carried out in three aspects: comparisons between inter-observer and inter-run variation, the fitness analysis between the automatically detected ellipse and the manual delineation, and the accuracy comparisons between automatic measurements and manual measurements in estimation of fetal weight (EFW). Experimental results show that the proposed method can provide consistent and accurate measurements. The reductions of the mean absolute difference and the standard deviation of EFW based on automatic measurements are about 1.2% and 2.1%, respectively, which indicate its potential in clinical antepartum monitoring application.

MR imaging characteristics of the normal fetal gastrointestinal tract and abdomen

Fetal magnetic resonance imaging (MRI) is considered a valuable second line imaging tool for confirmation, completion and correction of complex fetal ultrasonography findings. Fetal MRI has proven its value in pathologies of the central nervous system. Few studies have focussed on the value of fetal MRI in abdominal pathologies. With the continuing advances in hardware and software, fetal MRI is progressively valuable in fetal abdominal pathologies. A proper knowledge of the normal fetal abdominal anatomy and signal intensities is essential. The current manuscript reviews normal fetal abdominal anatomy.

A review of findings in fetal cardiac section drawings, Part 2: high abdominal views

OBJECTIVE

The goal of this presentation is to review some of the common and rare fetal heart abnormalities and to provide an easy approach to these findings with schematic drawings.

METHODS

Over the past 10 years, we collected cases in which the common views of the heart were abnormal and the differential diagnoses that existed for each. This presentation shows the normal sonographic sections and then variations of these sections and the associated anomalies. We used illustrative drawings to present these findings, enabling us to point out the main sonographic features of abnormalities of the heart.

RESULTS

This work reviews 4 fetal abnormalities in schematic drawings.

CONCLUSIONS

This short review highlights several of the anomalies that can be recognized on the common sonographic views. The drawings tend to simplify the findings but should serve as a basis for those doing fetal echocardiography when they encounter an unusual finding.