Macrosomia prediction using ultrasound fetal abdominal circumference of 35 centimeters or more

Ultrasound evaluation of the fetal fat tissue, heart, liver and umbilical cord measurements in pregnancies complicated by gestational and type 1 diabetes mellitus: potential application in the fetal birth-weight estimation and prediction of the fetal macrosomia

BACKGROUND

The aim of the study was to evaluate the ultrasound-derived measurements of the fetal soft-tissue, heart, liver and umbilical cord in pregnancies complicated by gestational (GDM) and type 1 diabetes mellitus (T1DM), and further to assess their applicability in the estimation of the fetal birth-weight and prediction of fetal macrosomia.

METHODS

Measurements were obtained from diet-controlled GDM (GDMG1) (n = 40), insulin-controlled GDM (GDMG2) (n = 40), T1DM (n = 24) and healthy control (n = 40) patients. The following parameters were selected for analysis: fetal sub-scapular fat mass (SSFM), abdominal fat mass (AFM), mid-thigh fat/lean mass (MTFM/MTLM) and inter-ventricular septum (IVS) thicknesses, heart and thorax circumference and area (HeC/HeA; ThC/ThA), liver length (LL), umbilical cord/vein/arteries circumference and area (UmC/UmA; UvC/UvA; UaC/UaA) together with total umbilical vessels (UveA) and Wharton's jelly area (WjA). Regression models were created in order to assess the contribution of selected parameters to fetal birth-weight (FBW) and risk of fetal macrosomia.

RESULTS

Measurements of the fetal SSFM, AFM, MTFM, MTFM/MTLM ratio, HeC, HeA, IVS, LL, UmC, UmA, UaC, UaA, UveA and WjA were significantly increased among patients with GDMG2/T1DM as compared to GDMG1 and/or control groups (p < .05). The regression analysis revealed that maternal height as well as fetal biparietal diameter, abdominal circumference (AC), AFM and LL measurements were independent predictors of the FBW (p < .05). In addition, increase in the fetal AFM, AC and femur length (FL) was associated with a significant risk of fetal macrosomia occurrence (p < .05). The equation developed for the FBW estimation [FBW(g) = - 2254,942 + 17,204 * FL (mm) + 105,531 * AC (cm) + 131,347 * AFM (mm)] provided significantly lower mean absolute percent error than standard formula in the sub-group of women with T1DM (5.7% vs 9.4%, p < .05). Moreover, new equation including AC, FL and AFM parameters yielded sensitivity of 93.8%, specificity 77.7%, positive predictive value 54.5% and negative predictive value of 97.8% in the prediction of fetal macrosomia.

CONCLUSIONS

Ultrasound measurements of the fetal soft tissue, heart, liver and umbilical cord are significantly increased among women with GDM treated with insulin and T1DM. In addition to standard biometric measurements, parameters, such as AFM, may find application in the management of diabetes-complicated pregnancies.

Sonographic and other nonglycemic factors can predict large-for-gestational-age infants in diet-managed gestational diabetes mellitus: A retrospective cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. Left untreated or poorly controlled, GDM results in adverse infant outcomes such as large for gestational age (LGA). This study aims to identify nonglycemic maternal and fetal factors predictive of LGA outcomes in pregnancies complicated by diet-managed GDM.

METHODS

This was a retrospective cohort study of singleton pregnancies complicated by diet-managed GDM from 2004 to 2015. Multiple logistic regression analysis was performed on maternal and perinatal factors to identify risk factors for LGA. In addition, a subset univariate analysis was conducted for pregnancies in which fetal ultrasound abdominal circumference measurements were available at gestational weeks 18 to 22, 24 to 28, and 29 to 33.

RESULTS

A total of 1064 women were included, delivering 123 LGA infants. Women with higher parity (odds ratio [OR] 1.44; CI, 1.23-1.68; P < .001) and higher prepregnancy body mass index (BMI) (OR 1.09; CI, 1.06-1.12; P < .001) were more likely to have LGA infants. Maternal smoking (OR 0.30; CI, 0.14-0.62; P = .001) and higher gestational age at birth (OR 0.91; CI, 0.84-0.99; P = .018) were associated with reduced risk. Subset univariate analysis showed that fetal abdominal circumference measurements at weeks 24 to 28 and 29 to 33 beyond the 75th percentile (OR 5.92 and 13.74, respectively) and 90th percentile (OR 4.57 and 15.89, respectively) were highly predictive of LGA.

CONCLUSIONS

Parity, smoking status, maternal BMI, gestational age, and ultrasound fetal abdominal circumference measurements were identified as useful predictors of LGA. Presence of these predictors may prompt closer monitoring of pregnancy and early therapeutic intervention to improve management and reduce the risk of adverse fetal and maternal outcomes.

Ultrasound (in)accuracy: it's in the formulae not in the technique - assessment of accuracy of abdominal circumference measurement in term pregnancies

Introduction: Fetal abdominal circumference (AC) is utilised in calculations for the estimation of fetal weight (EFW) and has been proposed as a method of monitoring diabetic pregnancies. We evaluated true ultrasound accuracy by comparing fetal AC biometry with neonatal anthropometry and compared this with standard ultrasound estimations of fetal weight.

Methods: A prospective observational study was performed at a tertiary referral centre. Women who were having their confinement of a term, singleton gestation either by induction of labour or elective caesarean section from 2009–2011 were approached to participate. An ultrasound was performed within 24 hours of delivery measuring the biometric parameters of AC, head circumference (HC), biparietal diameter and femur length. Following delivery the AC, HC and birthweight were measured on the neonate.

Results: Fifty‐two patients were enrolled in the study with data collected from 50. Mean AC measurement was 35.1 ± 2.1 cm and birth weight was 3596 ± 517 g. A Bland‐Altman plot was used to compare the two AC measurements with the 95% limits of agreement ranging from −2.33–4.69 cm around a mean difference of 1.2 cm. Mean percentage error was 5.0% and 6.2% for the AC and HC measurements respectively, in comparison with percentage errors of 7.0–13.8% for estimation of fetal weight (EFW) from 27 formulae.

Conclusions: Sonographic AC measurement is accurate in term pregnancies, with a percentage error less than HC or EFW. Perceptions of ultrasound inaccuracy may relate to the application of formulae rather than the ultrasound technique itself. Fetal surveillance using serial AC measurement has been proposed, in particular monitoring of diabetic pregnancies and in such a group AC may be easier and faster to obtain and more meaningful than EFW.

Association of Fetal Abdominal-Head Circumference Size Difference With Shoulder Dystocia: A Multicenter Study

Objective This study aims to determine if shoulder dystocia is associated with a difference in the fetal abdominal (AC) to head circumference (HC) of 50 mm or more noted on antenatal ultrasound. Study Design A multicenter matched case-control study was performed comparing women who had shoulder dystocia to controls who did not. Women with vaginal births of live born nonanomalous singletons ≥ 36 weeks of gestation with an antenatal ultrasound within 4 weeks of delivery were included. Controls were matched for gestational age, route of delivery, and diabetes status. Results We identified 181 matched pairs. Only 5% of the fetuses had an AC to HC of ≥ 50 mm. The proportion of AC to HC difference of ≥ 50 mm was significantly higher in shoulder dystocia cases (8%) than controls (1%, p = 0.002). With multivariate regression, the three significant factors associated with shoulder dystocia were AC to HC ≥ 50 mm (odds ratio [OR], 7.3; confidence interval [CI], 1.6-33.3; p = 0.010), femur length (OR, 1.1; CI, 1.0-1.2; p = 0.002), and induced labor (OR, 1.8; CI, 1.1-3.1; p = 0.027). Conclusion A prenatal ultrasound finding of a difference in AC to HC of ≥ 50 mm while uncommon is associated with shoulder dystocia.

Sonographic biometry in the early third trimester: A comparison of parameters to predict macrosomia at birth

PURPOSE

To compare the estimated fetal weight (EFW), abdominal circumference (AC), and femur length (FL), measured on sonographic (US) examinations at 28-34 weeks of gestation to determine the best predictor of macrosomia at birth.

METHODS

We retrospectively evaluated 3,857 consecutive, term, singleton pregnancies. The AC, FL, and EFW were compared with birth weights (BW) of >4,000 g and >4,500 g.

RESULTS

There was a statistically significant association between the AC and FL and a BW > 4,000 g or >4,500 g (p < 0.001) whether both or either were in the >90th percentile. There was no statistically significant association between an EFW in the >90th percentile and either BW cutoff. An AC in the >90th percentile alone was the best predictor for macrosomia at birth, with sensitivity, specificity, and positive and negative predictive values of 75%, 74%, 24%, and 96%, respectively (95% confidence intervals [CI]: 73-76%, 73-76%, 23-26%, and 96-97%, respectively), for a BW > 4,000 g. When an AC in the >90th percentile was used to predict a BW > 4,500 g, the sensitivity improved to 88%, but the positive predictive value fell to 5%. Receiver operating characteristic curves comparing the distributions of stratified AC values for BW cutoffs of 4,000 and 4,500 g found the highest areas under the curve of 0.80 (95% CI: 0.77-0.82) and 0.87 (95% CI: 0.83-0.90), respectively.

CONCLUSIONS

An AC in the >90th percentile at 28-34 weeks' gestation is the best sonographic predictor of macrosomia at birth. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:243-248, 2015.

Association between fetal abdominal circumference and birthweight in maternal hyperglycemia

OBJECTIVES

To compare fetal abdominal circumference and its relationship with birthweight at increasing gestational ages in the context of maternal hyperglycemia of varying severity.

DESIGN

Retrospective cohort study.

SETTING

Two centers participated in building one database.

POPULATION

A total of 1538 Korean pregnant women were subjected to a two-step approach to diagnose gestational diabetes mellitus.

METHODS

Pregnant women were classified into gestational diabetes mellitus, borderline gestational diabetes mellitus, and normal groups. Fetal abdominal circumferences, which were measured with ultrasound at 4-week intervals starting at 16 weeks of gestation and ending prior to delivery, were evaluated in the groups.

MAIN OUTCOME MEASURE

The significance of fetal abdominal circumferences as predictors or risk factors of macrosomia/large-for-gestational age.

RESULTS

Fetal abdominal circumferences measured from 16 weeks of gestation until prior to delivery predicted birthweight in all groups with some exceptions. Fetal abdominal circumferences measured from 32 weeks of gestation until prior to delivery were predictive of macrosomia in all groups. Fetal abdominal circumferences measured from 28 weeks of gestation until prior to delivery were predictive of neonates being large-for-gestational age in all groups. Fetal abdominal circumferences measured at 16 and 24 weeks of gestation were also predictive of large-for-gestational age in the borderline gestational diabetes mellitus group. Fetal abdominal circumference measured at 24 weeks of gestation was also a predictor of macrosomia/large-for-gestational age in normal women.

CONCLUSIONS

Fetal abdominal circumferences measured during the second and especially third trimesters were significantly associated with excessive birthweight, irrespective of the severity of maternal glucose intolerance.

Antenatal macrosomia prediction using sonographic fetal abdominal circumference in South Tunisia

Introduction

Identifying newborns who weight 4000 g or more is important because birth of macrosomic fetuses is associated with adverse peripartum outcomes. Ultrasound is widely used for this purpose Our objective was to evaluate the diagnostic value of sonographic measurement of fetal abdominal circumference (AC) over 350 mm for the prediction of fetal macrosomia and shoulder dystocia, to specify factors that could generate errors in its measure.

Methods

A retrospective clinical trial was conducted at the Department of Obstetrics and Gynecology, Hédi Chaker Hospital, Sfax, Tunisia. The study consisted of comparing two groups of singleton newborns: the first group (n=465) includes macrosomic babies and the second group (n=465) includes the non macrosomic ones. All women underwent sonographic measurements of the fetal abdominal circumference (AC) within 72 hours before delivery. The AC values were correlated to actual fetal birth weight. The cut-off value of AC for predicting of fetal macrosomia was analyzed.

Results

A cut-off value of abdominal circumference ≥350 mm, in predicting of fetal macrosomia., had a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value: 78.7%, 76.8%, 77%, 92.6%, and 49.2%, respectively. In macrosomic group obesity was significantly more frequent when AC≥350mm.

Conclusion

The fetal AC measurement was useful in predicting of fetal macrosomia. An AC measurement AC≥350mm could help to suspect shoulder dystocia.

Reducing the risk of shoulder dystocia and associated brachial plexus injury

Despite persisting controversy over shoulder dystocia prediction, prevention, and injury causation, the authors find considerable evidence in recent research in the field to recommend additional guidelines beyond the current American College of Obstetricians and Gynecologists and Royal College of Obstetricians and Gynecologists guidelines to improve clinical practice in managing patients at risk for experiencing shoulder dystocia. In this article, the authors offer health care providers information, practical direction, and advice on how to limit shoulder dystocia risk and, more importantly, to reduce adverse outcome risk.

How many sonograms are needed to reliably predict the absence of fetal overgrowth in gestational diabetes mellitus pregnancies?

OBJECTIVE

Serial measurements of the fetal abdominal circumference have been used to guide metabolic management of pregnancies complicated by gestational diabetes mellitus (GDM). A reduction in the number of repeat ultrasound examinations would save resources. Our purpose was to determine the number of serial abdominal circumference measurements per patient necessary to reliably predict the absence of fetal overgrowth.

RESEARCH DESIGN AND METHODS

Women who had GDM were asked to return for repeat ultrasound at 3- to 4-week intervals starting at initiation of care (mean 26.9 ± 5.7 weeks). Maternal risk factors associated with fetal overgrowth were determined.

RESULTS

A total of 4,478 ultrasound examinations were performed on 1,914 subjects (2.3 ± 1.2 per pregnancy). Of the 518 women with fetal abdominal circumference >90th percentile, it was diagnosed in 73.9% with the first ultrasound examination at entry and in 13.1% with the second ultrasound examination. Of the fetuses, 85.9 and 86.9% of the fetuses were born non-large for gestational age (LGA) when abdominal circumference was <90th percentile at 24-27 weeks and 28-32 weeks, respectively, and 88.0% were born non-LGA when both scans showed normal growth. For those women who had no risk factors for fetal overgrowth (risk factors: BMI >30 kg/m², history of macrosomia, and fasting glucose > 100 mg/dl), the accuracy of prediction of a non-LGA neonate was 90.0, 89.5, and 95.2%. The predictive ability did not increase with more than two normal scans.

CONCLUSIONS

The yield of sonographic diagnosis of a large fetus drops markedly after the finding of a fetal abdominal circumference <90th percentile on two sonograms, which excludes with high reliability the risk of a LGA newborn. The ability was enhanced in women who had no risk factors for neonatal macrosomia.

A new algorithm for improving fetal weight estimation from ultrasound data at term

Objective

The purpose of this retrospective study was to find a method of improving the accuracy of fetal birth weight estimation on the basis of traditional ultrasonographic measurements of the head, thorax, and femur at term. In this context, we analyzed a novel regression method comparing to existing algorithms.

Methods

The delivery records of two hospitals were searched for women who delivered macrosomic infants, and the patients’ medical records were retrospectively reviewed in order to derive clinical and ultrasonographic data at term. A total of 223 patients with macrosomic infants (birth weight > 4,000 g) were identified. These patients were complemented by data for 212 women who had ultrasound fetal assessments of less than 4,000 g. We used the method of isotonic regression to construct a birth weight prediction function that increases monotonically with each of the input variables and which minimizes the empirical quadratic loss.

Results

A suspicion of macrosomia was based on a history of macrosomia, fundal height, and sonographic weight estimation >4,000 g. The mean period between ultrasound weight estimation and delivery was 7.2 days. The ability of the biometric algorithms developed to predict fetal weight at term ranged between a mean absolute error of 312 and 344 g, given a confidence interval of 95%. We demonstrate that predictions of birth weight on the basis of ultrasound data can be improved significantly, if an isotonic regression model is used instead of a linear regression model.

Conclusions

This study demonstrates that ultrasound detection of macrosomia can be improved using the isotonic regression method.

The fetus of a diabetic mother: sonographic evaluation

Maternal hyperglycemia is responsible for many fetal adverse outcomes. Ultrasound examination of these pregnancies aims at an early detection of congenital malformations, assessment of fetal well-being, and fetal growth. This evaluation will influence clinical decision in determining the best time and mode of delivery. We reviewed data from the literature on accuracy, usefulness, and indications of ultrasound examinations in pregnancies complicated with diabetes mellitus, whether pregestational or gestational.

Prévention de la dystocie des épaules par la sélection échographique en début de travail des fœtus à fort périmètre abdominal

OBJECTIVE

Prevent shoulder dystocia occuring with macrosomic foetuses, by an ultrasound screening, at the beginning of labour, made by a member of obstetrics staff.

MATERIAL AND METHOD

A prospective study in the maternity hospital, la Mère et l'Enfant of University Teaching Hospital, Besançon, about 170 patients. We have measured only one parameter: the foetal abdominal circumference (AC).

RESULTS

An AC>or=350 mm had a sensitivity of 100% to detect newborns of birth weight>or=4250 g.

CONCLUSION

An AC>or=350 mm measured during labour by a member of obstetrics staff allow to alert and to make the staff sensitive to a risk of macrosomia and shoulder dystocia.

[Accuracy of ultrasonic fetal weight estimation using head and abdominal circumference and femur length]

INTRODUCTION

Former investigations have shown that the accuracy of fetal weight estimation is significantly higher if several ultrasonic fetal parameters are measured, because the total body mass depends on the size of fetal head, abdominal circumference and femur length. The aim of this investigation was to establish the best regression model, that is a number of combinations of fetal parameters providing the most accurate fetal weight estimation in utero in our population.

MATERIAL AND METHODS

This prospective study was carried out at the Gynecology and Obstetrics Clinic of the Clinical Center Novi Sad. It included 270 pregnant women with singleton pregnancies within 72 hours of delivery who underwent ultrasound measurements of the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL).

RESULTS

In regard to fetal weight estimation formulas, the deviation was lowest using regression models that simultaneously analyzed four fetal parameters (0. 55%) with SD +/- 7.61%. In these models the estimates of fetal weights were within +/- 5% of actual birth weight in 48.89%, and within +/- 10% of actual birth weight in 81.48%. Good results were also obtained using AC, FL measurements (0.92% +/- 8.20) as well as using AC, HC, FL measurements (-1.45% +/- 7.81). In our sample the combination of AC and FL model gave better results in fetal weight estimation (0.92 +/- 8.20%) than the one using BPD and AC (2.97 +/- 8.83%). Furthermore, the model using parameters AC, HC and FL showed a lower error in accuracy (-1.45 +/- 7.81%) than the model using BPD, AC and FL (2.51 +/- 7.82%).

CONCLUSION

This investigation has confirmed that the accuracy of fetal weight estimation increases with the number of measured ultrasonic fetal parameters. In our population the greatest accuracy was obtained using BPD, HC, AC and FL model. In cases when fast estimation of fetal weight is needed, AC, HC, FL model may be appropriate, but if fetal head circumference cannot be measured (amnion rupture and/or fetal head already in the pelvis) the AC, FL model should be used.

Accuracy of estimated fetal weight in shoulder dystocia and neonatal birth injury

OBJECTIVE

This study was undertaken to determine whether there is any difference in the rate of error of estimated fetal weight (EFW) in cases of shoulder dystocia compared with controls.

STUDY DESIGN

Women whose delivery was complicated by shoulder dystocia were studied and compared with a control group matched for parity, race, labor type (spontaneous or induced), and birth weight (BW). Accuracy (%) was defined as [(EFW-BW)/BW] x 100. The primary outcome of the study was rate of EFW underestimation error 20% or greater.

RESULTS

During the 5-year study period, there were 206 cases of shoulder dystocia that met all study criteria. There was no difference in the number of patients that had EFW underestimation error 20% or greater (shoulder dystocia 9.8% vs control 12.8%; P = .38). There was also no difference in the number of patients that had EFW underestimation error 20% or greater between shoulder dystocia with and without injury (injury 8.3% vs no injury 7.1%; P = .79).

CONCLUSION

EFW underestimation error in cases of shoulder dystocia is an infrequent event and does not occur more often than in deliveries without shoulder dystocia.

Fetal monitoring in type 1 diabetic pregnancies

Stillbirth and perinatal mortality rates are 5 times greater for an insulin-dependant diabetic mother than in the general population. Neonatal and infant mortality rates are 15 and 3 times greater, respectively. In addition, macrosomia is a major problem resulting in both fetal and maternal injury. Fetal monitoring is considered mandatory in such pregnancies. The rational approach would be to use surveillance strategies based on the underlying pathophysiology. However, in the diabetic pregnancy, the underlying pathophysiology is poorly understood and is likely to be multifactorial. Thus, in practice, a pragmatic approach is followed using methods that are applied in other high-risk pregnancies although the pathophysiology is different. Given the limitations in the predictive power of many fetal monitoring methods and the lack of randomised controlled trials, it is not surprising that there is no agreement over the best way to monitor fetal health in diabetic pregnancies. This article analyses the evidence regarding the value of these tests and proposed protocols for their use in the context of the diabetic pregnancy.

Sonographic and clinical methods in the diagnosis of macrosomia

Receiver operator characteristic curves for both clinical and sonographic predictions of macrosomia subsume areas between 0.81 and 0.95, significantly larger than the area of 0.5 that indicates a useless test. Thus, these tests are defined as useful from a statistical point of view. Prediction of macrosomia by clinical or imaging techniques, however, is limited by the substantial false-positive and false-negative rates inherent in these tests. We recommend that physicians continue to use clinical methods to estimate fetal weight, including asking women with parity to provide their own estimates. We recognize that the relative error associated with clinical or sonographic estimates of fetal weight limits their use in clinical practice. Sonographic laboratories may improve their results by performing ROC curve analysis on their own data and by selecting cutoff values that best predict macrosomia in their setting. Serial sonographic measurements that are above the limits chosen to define macrosomia increase the likelihood that a birth weight will be macrosomic. Separate ROC curves must be generated for twins and breech presentations and for patients with diabetes to answer weight-related clinical questions such as mode and timing of delivery. Three-dimensional ultrasound and magnetic resonance imaging are expected to generate ROC curves for estimates of fetal weight that are better than those for two-dimensional ultrasound or clinical estimates. Such analyses have yet to be published.

Estimating fetal weight in the management of macrosomia

The purpose of this review is to examine the evidence that, including estimates of fetal macrosomia in patient care, will decrease adverse perinatal outcomes. A literature search for the years 1980 to 1999 was used. Shoulder dystocia and brachial plexus injuries occur more often in macrosomic than in non-macrosomic neonates. However, 26 to 58 percent of shoulder dystocias and 24 to 44 percent of brachial plexus injuries occur to babies weighing less than 4000 gm. Persistence of impairment is extremely rare. Neither historical nor clinical factors have strong positive predictive values for macrosomia. From 15 to 81 percent of the babies predicted to be macrosomic are confirmed by birth weight. Of babies determined to be macrosomic at birth, only 50 to 100 percent were successfully predicted. Shoulder dystocia and brachial plexus injuries are unpredictable events. Available evidence suggests that planned interventions based on estimates of fetal weight do not reduce the incidence of shoulder dystocia and do not decrease adverse outcomes attributable to fetal macrosomia.