Accuracy of sonographic estimation of weight in fetuses with abdominal wall defects

Abstract

Background: Accurate estimation of fetal weight is essential in guiding management of fetuses with abdominal wall defects (AWDs), as growth restriction is an important predictor of perinatal morbidity and mortality. Several sonographic formulae are available involving multiple biometric parameters, but abdominal circumference measurements may underestimate weight in fetuses with AWDs. No formula has yet shown superior accuracy. Aims: The objectives of this study were to evaluate, in fetuses with gastroschisis and omphalocoele, the accuracy of a sonographic estimated fetal weight (EFW) formula proposed by Siemer and colleagues, specifically for use in fetuses with AWDs compared to the commonly used Hadlock IV formula in estimating fetal weight, and detecting small for gestational age (SGA) fetuses. Materials and Methods: A retrospective cohort of 113 fetuses with AWDs was identified from an Australian teaching hospital over 13 years. Pregnancy data and sonographic fetal biometry parameters were obtained. The accuracy of each formula in predicting birthweight was compared using Bland-Altman limits of agreement, and the intraclass correlation coefficient between EFW and actual birthweight. Performance of each formula in detecting SGA fetuses was determined. Results: The Siemer and Hadlock formulae have similar accuracies for predicting birthweight in fetuses with AWDs. The Hadlock formula has a higher detection rate for SGA < 10 th centile and < 3 rd centile compared to the Seimer formula (84% vs 68% and 83% vs 67% respectively), albeit with a higher false-positive rate. Conclusion: There is no clear clinical advantage in using the Siemer formula, which is specifically designed for fetuses with AWDs, over the Hadlock formula to estimate weight in fetuses with AWDs.

Embriologia da Parede Abominal Aplicada aos Defeitos da Parede Abdominal : Aspectos Translacionais

“…Na gastrosquise o problema é diretamente associado com exposição visceral ao líquido amniótico e subsequente perda proteica. Já na onfalocele a restrição de crescimento é menos comum e geralmente associada à síndromes genéticas e outras malformações (14)(15)(16).…”

Prediction of Neonatal Growth Restriction in Fetuses With Gastroschisis by Early Third Trimester Ultrasonography Utilizing Contemporary Birth Weight Percentiles

“…The traditional threshold of EFW less than the 10th percentile Previous studies evaluating ultrasound prediction of FGR in fetuses with gastroschisis have focused on EFW obtained as close to delivery as possible compared to actual birth weights, and some included fetuses with omphalocele. 8,9,[21][22][23][24][25] Nicholas et al found the Hadlock I formula to be the best screening test for FGR. In their study, the Hadlock formula had better specificity when compared to the Siemer formula, which excluded the abdominal circumference (AC) in its calculations.…”

“…5,6 This has prompted investigation of alternative EFW equations which do not include the AC measurement. 5,7,8 Fetuses with gastroschisis have a higher incidence of fetal growth restriction (FGR) compared with those without abdominal wall defects. 6 Infants with gastroschisis whose birth weights are less than the tenth percentile fare worse than those with higher birth weight.…”

“…Due to bowel herniation, fetuses with gastroschisis often have smaller abdominal circumferences which may result in EFW underestimation 5,6 . This has prompted investigation of alternative EFW equations which do not include the AC measurement 5,7,8 …”

Investigation of a connection between abdominal wall defects and severity of the herniation in fetuses with gastroschisis and omphalocele

“…Omphalocele is a AWD at the umbilicus, and the viscera outside the belly are covered by a membrane 2 – 4 . Patients with AWDs have an increased incidence of intrauterine growth restriction, and, therefore, the estimation of weight in fetuses with AWDs during gestational ultrasonography is more difficult than for normal fetuses 5 – 7 .…”