Estimating fetal weight in gastroschisis: A 10 year audit of outcomes at the National Maternity Hospital.

ABSTRACT

OBJECTIVE: To identify whether conventional methods of estimating fetal growth (Hadlock's formula), which relies heavily on abdominal circumference measurements, are accurate in fetuses with gastroschisis. METHODS: A retrospective cohort study was performed between the period January 1, 2011 and December 31, 2021 in a tertiary referral maternity hospital identifying all pregnancies with a diagnosis of gastroschisis. Projected fetal weight was obtained using the formula (EFW [Hadlock's formula] + 185 g × [X/7]) where X was the number of days to delivery. RESULTS: During the study period 41 cases were identified. The median maternal age was 25. The median BMI was 25 and 63% were primiparous women (n = 26). Median gestation at diagnosis was 21 weeks. Median gestation at delivery was 36 weeks. A total of 4.8% of mothers had a history of drug use (n = 2). The rate of maternal tobacco use was 21.9% (n = 9). A total of 4.8% of fetuses had additional congenital anomalies including amniotic band syndrome and myelomeningocele (n = 2). Estimated fetal weight (EFW) and birth weight data were available for 34 cases. A Wilcoxon signed-rank test showed projected EFW using Hadlock's formula did not result in a statistically significant different birth weight (Z = -1.3, P = 0.169). Median projected weight and actual birth weight were 2241.35 and 2415 g respectively. Median difference was 0.64 g (95% CI -148 to -28.5). CONCLUSION: Our data showed accuracy using standard formulae for EFW in fetuses with gastroschisis.