Ultrasound fetal biometry charts for a North American Caucasian population

Autopsy-Based Growth Charts May under-Detect Fetal Growth Restriction at Autopsy

Background: Accurate identification of fetal growth restriction in fetal autopsy is critical for assessing causes of death. We examined the impact of using a chart derived from ultrasound measurements of healthy fetuses (World Health Organization fetal growth chart) versus a chart commonly used by pathologists (Archie et al.) derived from fetal autopsy-based populations in diagnosing small-for-gestational-age (SGA) birth in perinatal deaths. Study Design: We examined perinatal deaths that underwent autopsy at BC Women's Hospital, 2015-2021. Weight centiles were assigned using the ultrasound-based fetal growth chart for birthweight and autopsy-based growth chart for autopsy weight. Results: Among 352 fetuses, 30% were SGA based on the ultrasound-based fetal growth chart versus 17% using the autopsy-based growth chart (p < 0.001). Weight centiles were lower when using the ultrasound-based versus autopsy-based growth chart (median difference of 9 centiles [IQR 2, 20]). Conclusions: Autopsy-based growth charts may under-classify SGA status compared to ultrasound-based fetal growth charts.

Selection of Standards for Sonographic Fetal Head Circumference by Use of z-Scores

OBJECTIVE

 This study aimed to evaluate which of five established norms should be used for sonographic assessment of fetal head circumference (HC).

STUDY DESIGN

 Cross-sectional study using pooled data from four maternal-fetal medicine practices. Inclusion criteria were singleton fetus, gestational age 220/7 to 396/7 weeks, biometry measured, and fetal cardiac activity present. Five norms of HC were studied: Jeanty et al, Hadlock et al, the INTERGROWTH-21st Project (IG-21st), the World Health Organization Fetal Growth Curves (WHO), and the National Institutes of Child Health and Human Development Fetal Growth Studies unified standard (NICHD-U). The fit of our HC measurements to each norm was assessed by these criteria: mean z-score close to 0, standard deviation (SD) of z close to 1, low Kolmogorov-Smirnov D-statistic, high Youden J-statistic, close to 10% of exams >90th percentile, close to 10% of exams <10th percentile, and close to 2.28% of exams >2 SD below the mean.

RESULTS

 In 23,565 ultrasound exams, our HC measurements had the best fit to the WHO standard (mean z-score 0.10, SD of z = 1.01, D-statistic <0.01, J-statistic 0.83-0.94). The SD of the Jeanty reference was much larger than all the other norms and our measurements, resulting in underdiagnosis of abnormal HC. The means of the IG-21st and NICHD-U standards were smaller than the other norms and our measurements, resulting in underdiagnosis of small HC. The means of the Hadlock reference were larger than all the other norms and our measurements, resulting in overdiagnosis of small HC. Restricting the analysis to a low-risk subgroup of 4,423 exams without risk factors for large- or small-for-gestational age produced similar results.

CONCLUSION

 The WHO standard is likely best for diagnosis of abnormal HC. The Jeanty (Chervenak) reference suggested by the Society for Maternal-Fetal Medicine had poor sensitivity for microcephaly screening.

KEY POINTS

· There are >30 norms for fetal HC.. · It is unknown which norm should be used.. · The WHO standard fits our data best.. · The Chervenak reference is not sensitive for microcephaly..

Selection of Standards for Sonographic Fetal Femur Length by Use of z-scores

OBJECTIVES

 This study aimed to evaluate which of four established norms should be used for sonographic assessment of fetal femur length (FL).

STUDY DESIGN

 Cross-sectional study using pooled data from four maternal-fetal medicine practices. Inclusion criteria were singleton fetus, gestational age (GA) 220/7 to 396/7 weeks, biometry measured, and fetal cardiac activity present. Four norms of FL were studied: Hadlock et al, the INTERGROWTH-21st Project (IG-21st), the World Health Organization Fetal Growth Curves (WHO), and the National Institutes of Child Health and Human Development Fetal Growth Studies, unified standard (NICHD-U). The fit of our FL measurements to each norm was assessed by these criteria: mean z-score close to 0, standard deviation (SD) of z close to 1, Kolmogorov-Smirnov D-statistic close to zero, Youden J-statistic close to 1, approximately 5% of exams <5th percentile, and approximately 5% of exams >95th percentile.

RESULTS

 In 26,177 ultrasound exams, our FL measurements had the best fit to the WHO standard (mean z-score 0.15, SD of z 1.02, D-statistic <0.01, J-statistic 0.95, 3.4% of exams <5th percentile, 7.0% of exams >95th percentile). The mean of the IG-21st standard was smaller than the other norms and smaller than our measurements, resulting in underdiagnosis of short FL. The mean of the Hadlock reference was larger than the other norms and larger than our measurements, resulting in overdiagnosis of short FL. The SD of the NICHD-U standard was larger than the other norms and larger than our observations, resulting in underdiagnosis of both short and long FL. Restricting the analysis to a subgroup of 7,144 low-risk patients without risk factors for large- or small-for- GA produced similar results.

CONCLUSION

 Of the norms studied, the WHO standard is likely best for diagnosis of abnormal FL.

KEY POINTS

· There are >30 norms for fetal FL.. · It is unknown which norm should be used.. · Our data fit the World Health Organization standard better than the other norms..

SWAVE 2.0 Imaging of Placental Elasticity and Viscosity: Potential Biomarkers for Placenta-Mediated Disease Detection

Pregnancy complications such as pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are associated with structural and functional changes in the placenta. Different elastography techniques with an ability to assess the mechanical properties of tissue can identify and monitor the pathological state of the placenta. Currently available elastography techniques have been used with promising results to detect placenta abnormalities; however, limitations include inadequate measurement depth and safety concerns from high negative pressure pulses. Previously, we described a shear wave absolute vibro-elastography (SWAVE) method by applying external low-frequency mechanical vibrations to generate shear waves and studied 61 post-delivery clinically normal placentas to explore the feasibility of SWAVE for placental assessment and establish a measurement baseline. This next phase of the study, namely, SWAVE 2.0, improves the previous system and elasticity reconstruction by incorporating a multi-frequency acquisition system and using a 3-D local frequency estimation (LFE) method. Compared with its 2-D counterpart, the proposed system using 3-D LFE was found to reduce the bias and variance in elasticity measurements in tissue-mimicking phantoms. In the aim of investigating the potential of improved SWAVE 2.0 measurements to identify placental abnormalities, we studied 46 post-delivery placentas, including 26 diseased (16 IUGR and 10 PE) and 20 normal control placentas. By use of a 3.33-MHz motorized curved-array transducer, multi-frequency (80,100 and 120 Hz) elasticity measures were obtained with 3-D LFE, and both IUGR (15.30 ± 2.96 kPa, p = 3.35e^-5) and PE (12.33 ± 4.88 kPa, p = 0.017) placentas were found to be significantly stiffer compared with the control placentas (8.32 ± 3.67 kPa). A linear discriminant analysis (LDA) classifier was able to classify between healthy and diseased placentas with a sensitivity, specificity and accuracy of 87%, 78% and 83% and an area under the receiver operating curve of 0.90 (95% confidence interval: 0.8-0.99). Further, the pregnancy outcome in terms of neonatal intensive care unit admission was predicted with a sensitivity, specificity and accuracy of 70%, 71%, 71%, respectively, and area under the receiver operating curve of 0.78 (confidence interval: 0.62-0.93). A viscoelastic characterization of placentas using a fractional rheological model revealed that the viscosity measures in terms of viscosity parameter n were significantly higher in IUGR (2.3 ± 0.21) and PE (2.11 ± 0.52) placentas than in normal placentas (1.45 ± 0.65). This work illustrates the potential relevance of elasticity and viscosity imaging using SWAVE 2.0 as a non-invasive technology for detection of placental abnormalities and the prediction of pregnancy outcomes.

Addition of sildenafil citrate for treatment of severe intrauterine growth restriction: a double blind randomized placebo controlled trial

Background: Severe intrauterine growth restriction complicates approximately 0.4% of the pregnancies. It increases the risk of perinatal morbidity and mortality.Subjects and methods: A double blind placebo controlled trial was conducted in Beni Suef University hospitals during 2017. It included 46 pregnant women with severe intrauterine growth restriction. Women were randomly allocated into two groups each included 23 patients. Intervention group received sildenafil citrate 20 mg orally three times a day, in addition to fish oil and zinc supplementation. Control group received tablets similar to sildenafil and the same treatment as intervention group. Primary outcomes included improvement in umbilical and middle cerebral arteries pulsatility indices and abdominal circumference.Results: Umbilical and middle cerebral arteries Doppler indices showed significant difference between groups after intake of sildenafil. Umbilical artery pulsatility index decreased significantly (p value = .001) while middle cerebral artery pulsatility index increased significantly in intervention group (p value0.001). Moreover, abdominal circumference growth velocity improved after two weeks of sildenafil intake (p value = .001).Conclusions: Sildenafil citrate may improve uteroplacental and fetal cerebral perfusion in pregnancies complicated by severe intrauterine growth restriction. It also improves abdominal circumference growth velocity. A wide scale randomized trials are needed for evaluation of neonatal and long term morbidity and mortality outcomes of pregnancies treated by sildenafil citrate.

Fetal Biometric Charts and Reference Equations for Pregnant Women Living in Port Said and Ismailia Governorates in Egypt

AIM:

To construct new fetal biometric charts and equations for some fetal biometric parameters for women between 12^th and 41^st weeks living in Ismailia and Port Said Governorates in Egypt.

MATERIAL AND METHODS:

This cross-sectional study was carried out on 656 Egyptian women (from Ismailia and Port Said governorates) with an uncomplicated pregnancy, and all were sure of their dates. The selected group was between the 12^th and 41^st weeks of gestation, recruited from the district general hospital in Ismailia and Port Said to measure ultrasonographically biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL), then for each measurement separate regression models were fitted to estimate both the mean and the Standard deviation at each gestational age.

RESULTS:

New Egyptian charts were reported for BPD, HC, AC, and FL. Reference equations for the dating of pregnancy were presented. The mean of the previous measurements at 12^th and 41^st weeks were as follows: (23.37, 98.72), (83.05, 336.12), (67.85, 332.57) and (12.50, 74.92) respectively.

CONCLUSION:

New fetal biometric charts and regression equations for pregnant women living in Port Said & Ismailia governorates in Egypt.

Fetal Sex, Need for Insulin, and Perinatal Outcomes in Gestational Diabetes Mellitus: An Observational Cohort Study

PURPOSE

This was a prospective observational cohort study that aimed to determine whether fetal sex influences the maternal and fetal outcomes of gestational diabetes mellitus (GDM).

METHODS

In this study, 327 European primiparous women were consecutively recruited after diagnosis of GDM. AUC on the oral glucose tolerance test (OGTT), need for insulin therapy, maternal and obstetrical outcomes, and fetal fat mass (by measuring the thickness of the anterior abdominal subcutaneous tissue) were recorded and compared between the two subgroups of female and male fetuses.

FINDINGS

Despite the absence of differences in multiple comparisons of the OGTT, the AUC-OGTT was significantly higher in women carrying a male fetus (22.6 [3.2] mmol/L vs 19.7 [2.8] mmol/L). The abdominal fat thickness appeared to increase with gestational age, with higher growth in male fetuses than in female fetuses. The overall risk of need for insulin therapy was significantly higher in women carrying a male fetus (odds ratio = 1.837). At delivery, birthweight was higher in males than in females only if adjusted for gestational age, similarly for placental weight, otherwise there were no significant differences between the groups in total length of gestation, rates of cesarean delivery, and Apgar scores.

IMPLICATIONS

Overall, our data propose an association between fetal sex and GDM outcomes, suggesting the hypothesis that in maternal-fetal interactions, the fetus can affect maternal glucose metabolism.

Fetal biometry: Relevance in obstetrical practice

Ultrasound imaging in obstetrics and gynecology dates back to 1958 when The Lancet published the first article about the use of ultrasonography for fetal and gynecological assessments. It is now almost inconceivable, 60 years later, to think of effective performance in obstetrics and gynecology without the variety of ultrasound, for example, real time imaging, power and color Doppler, 3D/4D ultrasonography, etc. Such examinations facilitate the assessment of intrauterine fetal growth and development during pregnancy, provide alerts about the risk of pre-eclampsia and preterm birth, help identify anatomic reasons for infertility, diagnose ectopic pregnancies, uterine, ovary and tubal pathology. Ultrasonography is also used for diagnostic and treatment procedures during pregnancy or for the treatment of infertility. This article is an overview of the development of fetal ultrasound, the methodology and interpretation of ultrasound in the assessment of intrauterine fetal growth and fetal biometry standards both worldwide and in Lithuania.

Comparison of radiographic femur measurements in stillbirths and neonatal deaths to ultrasound measurements in ongoing pregnancies

Identifying growth abnormalities in stillbirths is clinically useful but complicated by maceration. This is an observational study of consecutive postmortem examinations in which femur lengths and gestational age at delivery were collected, along with associated congenital anomalies and extent of fetal maceration. Between 2005 and 2012, 1530 consecutive postmortem examinations were performed and the information recorded. Fragmented fetuses (417), live-born fetuses that survived for more than 24 hours (134), fetuses with any signs of maceration (419), fetuses with known anomalies (98), and records with missing data (249) were excluded. The analyses focused on the remaining 265 nonmacerated stillborn fetuses and infants that survived for less than 24 hours after birth. The relationship between gestational age at delivery and femur length was computed, and a quadratic equation fit the data well between 12 and 40 weeks' gestation (R  =  0.944). Gestational age-specific reference ranges for radiographic femur measurements in stillbirths are equivalent to those for ultrasound-determined measurements in ongoing pregnancies. These reference data may be useful in identifying growth abnormalities in nonmacerated stillborn fetuses.

The fetal cardiovascular response to increased placental vascular impedance to flow determined with 4-dimensional ultrasound using spatiotemporal image correlation and virtual organ computer-aided analysis

OBJECTIVE

We sought to determine if increased placental vascular impedance to flow is associated with changes in fetal cardiac function using spatiotemporal image correlation and virtual organ computer-aided analysis.

STUDY DESIGN

A cross-sectional study was performed in fetuses with umbilical artery pulsatility index >95th percentile (abnormal [ABN]). Ventricular volume (end-systole, end-diastole), stroke volume, cardiac output (CO), adjusted CO, and ejection fraction were compared to those of 184 normal fetuses.

RESULTS

A total of 34 fetuses were evaluated at a median gestational age of 28.3 (range, 20.6-36.9) weeks. Mean ventricular volumes were lower for ABN than normal cases (end-systole, end-diastole) with a proportionally greater decrease for left ventricular volume (vs right). Mean left and right stroke volume, CO, and adjusted CO were lower for ABN (vs normal) cases. Right ventricular volume, stroke volume, CO, and adjusted CO exceeded the left in ABN fetuses. Mean ejection fraction was greater for ABN than normal cases. Median left ejection fraction was greater (vs right) in ABN fetuses.

CONCLUSION

Increased placental vascular impedance to flow is associated with changes in fetal cardiac function.

Accuracy of sonography to predict estimated weight in fetuses with gastroschisis

OBJECTIVES

The purpose of this study was to determine whether sonographic formulas for estimating fetal weight are as accurate for fetuses affected with gastroschisis as they are for healthy fetuses. We hypothesized that because the most commonly used Hadlock formulas rely on the abdominal circumference as a biometric variable, estimates of birth weight are less reliable in fetuses with gastroschisis than in healthy fetuses.

METHODS

We performed a chart review of all fetuses with a prenatal diagnosis of gastroschisis at 3 tertiary care institutions from 1990 to 2008. Charts were reviewed for clinical and sonographic data. The estimated fetal weight at the prenatal sonogram closest to delivery was compared to the birth weight. Published Hadlock formulas using 4 biometric parameters were used to calculate the estimated fetal weight. Data analysis was performed using the Student t test and χ(2) test for continuous and categorical variables, respectively.

RESULTS

One hundred eleven patients with gastroschisis were identified. Sixty-six patients had a prenatal sonogram with a calculated estimated fetal weight within 7 days of delivery; 88 patients had a sonogram within 14 days. The mean birth weights ± SD were 2292 ± 559 and 2477 ± 531 g in the 0- to 7- and 8- to 14-day groups, respectively. Sonographic biometric measurements underestimated the birth weight by an average of 5.6%. Intrauterine growth restriction was predicted in 72% of all pregnancies but was only present in 52%.

CONCLUSIONS

Our study shows a systematic error of birth weight underestimation when using the Hadlock formulas in fetuses affected with gastroschisis.

Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size

BACKGROUND

Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.

OBJECTIVE

To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.

SEARCH STRATEGY

Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.

SELECTION CRITERIA

Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.

MAIN RESULTS

Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.

CONCLUSIONS

There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.

Prediction of adverse maternal outcomes in pre-eclampsia: development and validation of the fullPIERS model

BACKGROUND

Pre-eclampsia is a leading cause of maternal deaths. These deaths mainly result from eclampsia, uncontrolled hypertension, or systemic inflammation. We developed and validated the fullPIERS model with the aim of identifying the risk of fatal or life-threatening complications in women with pre-eclampsia within 48 h of hospital admission for the disorder.

METHODS

We developed and internally validated the fullPIERS model in a prospective, multicentre study in women who were admitted to tertiary obstetric centres with pre-eclampsia or who developed pre-eclampsia after admission. The outcome of interest was maternal mortality or other serious complications of pre-eclampsia. Routinely reported and informative variables were included in a stepwise backward elimination regression model to predict the adverse maternal outcome. We assessed performance using the area under the curve (AUC) of the receiver operating characteristic (ROC). Standard bootstrapping techniques were used to assess potential overfitting.

FINDINGS

261 of 2023 women with pre-eclampsia had adverse outcomes at any time after hospital admission (106 [5%] within 48 h of admission). Predictors of adverse maternal outcome included gestational age, chest pain or dyspnoea, oxygen saturation, platelet count, and creatinine and aspartate transaminase concentrations. The fullPIERS model predicted adverse maternal outcomes within 48 h of study eligibility (AUC ROC 0·88, 95% CI 0·84-0·92). There was no significant overfitting. fullPIERS performed well (AUC ROC >0·7) up to 7 days after eligibility.

INTERPRETATION

The fullPIERS model identifies women at increased risk of adverse outcomes up to 7 days before complications arise and can thereby modify direct patient care (eg, timing of delivery, place of care), improve the design of clinical trials, and inform biomedical investigations related to pre-eclampsia.

FUNDING

Canadian Institutes of Health Research; UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development, and Research Training in Human Reproduction; Preeclampsia Foundation; International Federation of Obstetricians and Gynecologists; Michael Smith Foundation for Health Research; and Child and Family Research Institute.

Cerebral biometry in fetal magnetic resonance imaging: new reference data

OBJECTIVES

To provide normal magnetic resonance imaging (MRI) reference biometric data of the fetal brain, to evaluate reproducibility and gender effect, to compare the two cerebral hemispheres and to compare MRI with ultrasonographic biometry, in a large cohort.

METHODS

Normal cerebral fetal MRI examinations were collected prospectively and several parameters were measured: the supratentorial space (bone and cerebral fronto-occipital and biparietal (BPD) diameters), the length of the corpus callosum (LCC), the surface area, height and anteroposterior diameter of the vermis, the transverse cerebellar diameter (TCD) and the anteroposterior diameter of the pons. We evaluated the interobserver reproducibility of measurements and the possible gender effect on measurements of bone BPD, TCD and LCC. We compared right and left hemispheres, right and left atria and ultrasound and MRI measurements.

RESULTS

The study included 589 fetuses, ranging from 26 to 40 weeks. Normal values (from 3(rd) to 97(th) percentile) are provided for each parameter. Interobserver agreement was excellent, with an intraclass correlation coefficient (ICC) > 0.75 for many parameters. The gender effect was evaluated in 372 cases and did not reveal any clinically meaningful difference. Comparison between the right and left cerebral hemispheres and between the right and left atria did not reveal any meaningful differences. Ultrasound and MRI measurements of BPD and TCD were compared in 94 cases and 48 cases, respectively, and the agreement was excellent (ICC = 0.85).

CONCLUSIONS

We present new reproducible reference charts for cerebral MRI biometry at 26-40 weeks' gestation, from a large cohort of fetuses.

Intrauterine restriction (IUGR)

Perinatal mortality and morbidity is markedly increased in intrauterine growth restricted (IUGR) fetuses. Prenatal identification of IUGR is the first step in clinical management. For that purpose a uniform definition and criteria are required. The etiology of IUGR is multifactorial and whenever possible it should be assessed. When the cause is of placental origin, it is possible to identify the affected fetuses. The major complication is chronic fetal hypoxemia. By monitoring the changes of fetal vital functions it is thus possible to improve both management and outcome. The timing of delivery is crucial but the optimal management scheme has not yet been identified. When IUGR is identified at very early gestational ages, serial assessments of the risk of continuing the in utero fetal life under adverse conditions versus the risks of the prematurity should be performed. Delivery of IUGR fetuses should take place in centers where appropriate neonatal assistance can be provided. Careful monitoring of the IUGR fetus during labor is crucial as the IUGR fetus can quickly decompensate once uterine contractions have started.

Anaesthetic management of a craniopagus conjoined twin delivery

We report the successful caesarean delivery of craniopagus conjoined twins in a 21-year-old using a neuraxial technique. Early diagnosis at 19(+5) weeks of gestation enabled thorough multidisciplinary antepartum planning. The multidisciplinary approach aimed to reduce maternal and fetal morbidity. Teams involved in the delivery included the specialities of obstetrics, neonatology, anaesthesia, paediatric neurosurgery and radiology. The delivery was complicated by an anterior placenta. The obstetricians used a J-shaped incision avoiding the placenta and making space for the fetal heads at delivery. Regional anaesthesia was used successfully in this case; although plans had been made should the mother need general anaesthesia intra-operatively. At delivery there were 17 members of the multidisciplinary team present in the operating theatre. They were from five specialities from two separate hospitals. We discuss the anaesthetic considerations for the delivery of conjoined twins and the multidisciplinary approach used in this case.

Reference charts and equations of Korean fetal biometry

OBJECTIVE

To construct new reference charts and equations for fetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur diaphysis length (FDL) from Korean fetuses at 12-40 weeks.

METHOD

Prospective cross-sectional data obtained in one center for 5 years from a population of pregnant women undergoing ultrasound examination between the 12th and 40th week of gestation. Exclusion criteria comprised all maternal and fetal conditions possibly affecting fetal biometry. No fetuses were excluded on the basis of abnormal biometry. For each measurement, regression models were fitted to estimate both the mean and the standard deviation at each menstrual age.

RESULTS

Biometric measurements were obtained for 10 455 fetuses. New charts and reference equations are reported for BPD, HC, AC and FDL. Reference equations are cubic models.

CONCLUSION

We present new Korean reference charts and equations for fetal biometry. They can be easily used in obstetric ultrasound studies for the Korean population.

Gastroschisis: Growth Patterns and a Proposed Prenatal Surveillance Protocol

OBJECTIVE

To assess intrauterine growth for fetuses with gastroschisis using retrospective serial ultrasound assessment from fetuses diagnosed prenatally with gastroschisis. The growth assessment could be available as a prospective tool to direct an antepartum fetal surveillance protocol.

METHODS

This is a retrospective review of all cases of gastroschisis evaluated prenatally at a single institution between February 1996 and March 2002. Charts were reviewed for serial ultrasound assessment, gestational age at delivery, mode of delivery, and birth weight. Growth assessment was determined for abdominal circumference, biparietal diameter, head circumference, femur length, and estimated fetal weight (IRB No. 2002-1-2648).

RESULTS

Forty patients had delivered by March 2002. One hundred and two ultrasound reports were reviewed. Gastroschisis growth curves showed that the 50th percentile was shifted to the right when compared to normal growth curves for abdominal circumference, biparietal diameter, head circumference, and femur length. The average birth weight was 2,359 g. Compared with a standard population, 44% (16/36) were below the 5th percentile, 61% (22/36) were below the 10th percentile, and 95% (34/36) were below the 50th percentile for gestational age. The average gestational age at delivery was 36.3 weeks. Mothers were nulliparous in 78%, with a mean age of 21.3 years.

CONCLUSIONS

(1) Fetuses with gastroschisis show a symmetric intrauterine growth restriction pattern consistent with early development of growth delay; (2) the 50th percentile biometry measurements for the gastroschisis population are shifted to the right on normal fetal growth curves; (3) the birth weight is at or below the 10th percentile in 61% of the newborns with gastroschisis, and (4) an antepartum surveillance protocol is proposed based on growth patterns of fetuses with gastroschisis.

The prenatal multiplier method for prediction of limb length discrepancy

OBJECTIVE

The purpose of this study was to produce a method of predicting limb length discrepancy in utero.

METHODS

Using available databases, we divided the femoral and tibial lengths at term by the femoral and tibial lengths at each week of gestation for each percentile. The quotients represent coefficients (multipliers) of limb segment growth at each prenatal age.

RESULTS

We found the prenatal multipliers to be independent of race, percentile, and gender from as early as 12 weeks' gestation. The prenatal multipliers are alike for femur and tibia.

CONCLUSIONS

The prenatal multiplier method allows for quick prediction of limb length discrepancy at term and at skeletal maturity from as early as 12 weeks' gestation. Future study is needed to validate this method clinically.

Cephalic index is not a useful sonographic marker for trisomy 21 and trisomy 18

OBJECTIVES

To evaluate whether the cephalic index (CI) in trisomy 21 (T21) and trisomy 18 (T18) fetuses is different from that in euploid fetuses, and if so, is this difference of clinical utility.

METHODS

Retrospective. Over an 18-month period, patients attending a single centre for routine advanced maternal age amniocentesis were recruited for a prospective study of ultrasound soft markers of aneuploidy. This prospective database was searched for cases with the following criteria: (1) occipitofrontal diameters (OFD) measured at least twice; (2) gestational age between 98 and 126 days either by ultrasound-confirmed menstrual dates or early second- trimester biometry; (3) no major central nervous system abnormalities detected on prenatal ultrasound, and (4) normal fetal karyotype. This constituted the control group. The study group consisted of all cases of prenatally diagnosed T18 and T21 identified in the same time period with criterion 2 as above. The fetuses in the study group had the OFD measured in a blinded fashion from the biparietal diameter images. CI (= mean biparietal diameter/mean OFD) was calculated for all fetuses. Pearson coefficient and regression analysis were used to determine independence of CI to gestational age in the control group. Standard descriptive statistics were used to describe interval data and two-tailed t test was used to compare means between the study and control groups. ROC curves were constructed to evaluate the clinical efficacy of CI for T18 and T21.

RESULTS

Five hundred and ninety-seven fetuses were available for analysis. There were 551 fetuses in the control group and 46 in the study group. Within the study group, there were 30 T21 and 16 T18 fetuses. Within the control group, CI was independent of gestational age (R = 0.026, p = 0.922). Mean CI for the control group was 0.802 (SD 0.040) and this was not statistical different from either the T21 group (mean 0.816, SD 0.042, p = 0.067) or the T18 group (mean 0.792, SD 0.057, p = 0.491). Area under the ROC curves was determined for both T18 and T21 and both had poor results (0.545 and 0.598, respectively). When CI was evaluated in the control group according to the two main ethnic groups in the study, there was a trend towards a statistical difference (p = 0.046) between the fetuses of Oriental and Caucasian mothers.

CONCLUSIONS

In this retrospective study, CI was not found to be statistically different between the study and control groups. Although a trend towards significance was seen with T21, this difference is not clinically useful. There may be interethnic differences in the CI between fetuses. CI is not useful for aneuploidy screening by ultrasound.

Fetal head biometry following in-utero repair of myelomeningocele

OBJECTIVE

To evaluate the impact of prenatal myelomeningocele repair on fetal head biometry.

METHODS

Fifty fetuses underwent open fetal myelomeningocele repair at our institution between January 1998 and July 2002. All had serial head circumference (HC) and lateral ventricular diameter (VD) measurements taken preoperatively and weekly for 8 weeks after repair. Cortical index (CI) was defined as HC/VD. Measurements were compared with gestational age-matched values from nomograms. One-sample t-test, ANOVA and repeated measures analysis were used to assess HC, VD and CI after fetal repair.

RESULTS

Preoperatively, the HC in fetuses with myelomeningocele was smaller than control values (186.4 vs. 198.8 mm, P = 0.0004). Eight weeks' postoperatively this difference had resolved (293 vs. 301.6 mm, P = 0.76). The mean increase in CI after repair was 20% (P = 0.02) compared with the predicted 51% in normal cases. The average increase in VD was 3.9 mm (38.8%, P < 0.001).

CONCLUSIONS

Mid-gestational repair of myelomeningocele alters fetal head growth. Increased CI suggests HC changes are not due to ventriculomegaly alone.

Neutrophil apoptosis in preeclampsia, do steroids confound the relationship?

AIM

To investigate the influence of maternal corticosteroid administration on neutrophil apoptosis in early onset preeclampsia.

METHODS

We investigated five groups: early onset preeclampsia (EOPET, <34 weeks, n = 10); late-onset preeclampsia (LOPET, > or =34 weeks, n = 7); normotensive intrauterine growth restriction (nIUGR, n = 11); normal pregnancy (NPC, n = 22); and non-pregnancy (n = 10). We examined, by flow cytometry, spontaneous neutrophil apoptosis after 18 h culture (hypodiploid DNA, Annexin V binding, propidium iodide [PI] permeability).

RESULTS

For the 10 women with EOPET exposed to betamethasone in the previous 48 h, we found that neutrophil apoptosis was not inappropriately inhibited, in contrast to our previous findings in women not thus exposed. Neither LOPET nor nIUGR differed from normal pregnancy.

CONCLUSION

Betamethasone alters the rate of spontaneous neutrophil apoptosis in EOPET. The anti-inflammatory influence of betamethasone may explain some of the differences between our previous and present findings with respect to neutrophil apoptosis in EOPET. Corticosteroids ameliorate the course of antenatal and postnatal preeclampsia. These results may reflect the mechanisms that underlie the transient improvements seen with antenatal dexamethasone use.

Screening for fetal well-being in a high-risk pregnant population comparing the nonstress test with umbilical artery Doppler velocimetry: a randomized controlled clinical trial

OBJECTIVE

The purpose of this study was to evaluate the ability of two different modes of antepartum fetal testing to screen for the presence of peripartum morbidity, as measured by the cesarean delivery rate for fetal distress in labor.

STUDY DESIGN

Over a 36-month period, all patients who were referred to the Fetal Assessment Unit at BC Women's Hospital because of a perceived increased fetal antepartum risk at a gestational age of > or =32 weeks of gestation were approached to participate in this study. Fetal surveillance of these women was allocated randomly to either umbilical artery Doppler ultrasound testing or nonstress testing as a screening test for fetal well-being. If either the umbilical artery Doppler testing or the nonstress testing was normal, patients were screened subsequently with the same technique, according to study protocol. When the Doppler study showed a systolic/diastolic ratio of >90th percentile or the nonstress testing was equivocal (ie, variable decelerations), an amniotic fluid index was performed, as an additional screening test. When the amniotic fluid index was abnormal (<5th percentile), induction and delivery were recommended. When the Doppler study showed absent or reversed diastolic blood flow or when the nonstress test result was abnormal, induction and delivery were recommended to the attending physician. Statistical comparisons between groups were performed with an unpaired t test for normally distributed continuous variables and chi(2) test for categoric variables.

RESULTS

One thousand three hundred sixty patients were assigned randomly to groups in the study; 16 patients were lost to follow up. Six hundred forty-nine patients received Doppler testing and 691 received nonstress testing. The mean number of visits for the Doppler test and nonstress test groups was two versus two, respectively. The major indications for fetal assessment included postdates (43%), decreased fetal movement (22%), diabetes mellitus (11%), hypertension (10%), and intrauterine growth restriction (7%). The incidence of cesarean delivery for fetal distress was significantly lower in the Doppler group compared with the nonstress testing group (30 [4.6%] vs 60 [8.7%], respectively; P <.006). The greatest impact on the reduction in cesarean deliveries for fetal distress was seen in the subgroups in which the indication for testing was hypertension and suspected intrauterine growth restriction.

CONCLUSION

Umbilical artery Doppler as a screening test for fetal well-being in a high-risk population was associated with a decreased incidence of cesarean delivery for fetal distress compared to the nonstress testing, with no increase in neonatal morbidity.

Abdominal circumference: a single measurement versus growth rate in the prediction of intrapartum Cesarean section for fetal distress

OBJECTIVE

The fetal abdominal circumference is the most sensitive ultrasound biometric measurement for predicting intrauterine growth restriction, which is associated with an increased risk of intrapartum fetal distress. We sought to evaluate and compare whether a third-trimester ultrasound measurement of abdominal circumference made within 1 week prior to delivery better predicts operative delivery for fetal distress when compared with the growth velocity of the abdominal circumference in the third trimester.

METHODS

Retrospective analysis was carried out of prospectively collected ultrasound data on 117 patients with singleton gestations who had had at least two ultrasound assessments performed less than 6 weeks apart in the third trimester, with the last ultrasound performed within 1 week prior to delivery. The abdominal circumference value of the last ultrasound prior to delivery was placed into one of three categories: < or = 5% centile, > 5 to < or = 10% centile and > 10% centile for gestational age. The growth velocity of the abdominal circumference per week was placed into one of three categories: < or = 5 mm/week, 6-10 mm/week and > or = 11 mm/week. The chi-squared test was used to compare differences between the incidence of fetal distress between the groups.

RESULTS

The incidences of Cesarean section for fetal distress in relation to a single measurement of the abdominal circumference were: < or = 5% centile, 8/23 (35%); > 5 to < or = 10% centile, 3/12 (25%); > 10% centile, 8/81 (10%) ( P < 0.05). The incidences of Cesarean section for fetal distress with the three abdominal circumference growth velocities were: < or = 5 mm/week, 9/55 (16%); 6-10 mm/week, 4/11 (36%); > or = 11 mm/week, 8/51 (16%) ( P = 0.9401).

CONCLUSION

A single measure of the fetal abdominal circumference made within 1 week prior to delivery is superior to an assessment of growth rate of the fetal abdomen in the third trimester in discriminating patients who require Cesarean section for fetal distress.

Fetal biometry: clinical, pathological, and technical considerations

Sonographic measurements of fetal ultrasound parameters are the basis for accurate determination of gestational age and detection of fetal growth abnormalities. Selection of the most useful single biometric parameter depends on the timing and purpose of measurement and is influenced by specific limitations. CRL (crown-rump length) is the best parameter for early dating of pregnancy. Biparietal diameter (BPD) maintains the closest correlation with gestational age in the second trimester. In cases of variation in the shape of the skull, head circumference is an effective alternative. Abdominal circumference is the most useful dimension to evaluate fetal growth, and femur length is the best parameter in the evaluation of skeletal dysplasia. Use of multiple predictors improves the accuracy of estimates. An individual approach to each pregnancy is recommended for fetal growth assessment. The various epidemiological factors involved in fetal growth should be considered and specific charts for different communities should be used when possible. The methods of fetal weight estimation with their limitations and potential errors are presented. Clinical application of fetal biometry in abnormal growth is discussed in cases of small- and large-for-gestational-age fetuses, chromosomal aberrations, and skeletal dysplasias.