(1107) The role of MSAFP screening in prenatal diagnosis of omphalocele

Objective: As serum screening for aneuploidies becomes less prevalent due to the uptake of non-invasive prenatal testing and improved prenatal imaging, it is unclear whether continued maternal-serum alpha-fetoprotein (MSAFP) screening results in earlier omphalocele detection compared to ultrasound alone. We explored whether MSAFP screening results in earlier omphalocele detection.

Study Design: This is an IRB-approved retrospective cohort study of prenatally detected omphalocele cases at our fetal referral center, from 08/2007-05/2023. Maternal, fetal, and neonatal outcomes were abstracted. We explored the association between MSAFP screening and gestational age at omphalocele diagnosis using bivariate analyses and the Mann-Whitney U test for nonparametric comparisons.

Results: Among 102 pregnancies with prenatally diagnosed omphalocele, 27 (26.4%) had MSAFP screening. Of these, 11 (41%) had MSAFP values ≥2.5 MoM and 16 (59%) did not have an elevated MoM; these findings did not correlate with omphalocele rupture or additional major anatomic defects (phi=0.368). The median gestational age at MSAFP screening was 17w3d. Among pregnancies with MSAFP screening, the median GA at first sonographic suspicion of omphalocele was 18w2d; however, among pregnancies without MSAFP screening the median GA was slightly earlier at 17w5d though this was not significant (p=0.75). There was also no difference between MSAFP and no-MSAFP cases in GA at sonographic confirmation of the omphalocele (p=0.87).

Conclusion: In this cohort of prenatally diagnosed omphaloceles, MSAFP was abnormally elevated in approximately 40% of cases. MSAFP screening was not associated with earlier sonographic suspicion for or prenatal confirmation of omphalocele. While there is a paucity of consistent data regarding whether MSAFP still aids in prenatal detection of gastroschisis and neural tube defects, MSAFP screening in this population did not lead to earlier omphalocele detection.