EP17.25: The outcomes of fetal intraumbilical vein varix: one comparative study

Fetal intra-abdominal umbilical vein varix (FIUVV), a focal dilatation of the umbilical vein ≥ 9 mm, is a rare malformation. The literature on FIUVV is scarce and inconsistent. The aim of this study was to compare the perinatal outcome of FIUVV to that of the normal fetal population. A retrospective cohort study including singleton pregnancies carrying a fetus prenatally diagnosed with FIUVV, delivering at a single, tertiary centre between 2012 -2022, was conducted. The control group consisted of singleton pregnancies, without FIUVV, delivering at our centre during the study period. Excluded were high-order pregnancies, pregnancies that delivered at other centres, and cases in which FIUVV resolved during follow-up. Compared were perinatal outcomes including the rates of small for gestational age (SGA), congenital anomalies, fetal death, Caesarean section due to non-reassuring fetal heart rate, etc. A composite adverse outcome composed of individual adverse outcomes, was compared. Included were 142 singleton pregnancies carrying a fetus diagnosed with FIUVV and 99,715 controls. There were no fetal deaths among FIUVV cases, delivering up to 42.1 weeks of gestation (median 37.6 weeks, IQR 37.1-38.5 weeks). There was a higher rate of congenital anomalies and SGA in the study group (15.49% vs. 0.84%, p < 0.01 and 9.85% vs 5.41%, p = 0.02, respectively). Although there was a higher preterm birth rate in the study group (15.5% vs. 7.2%, p < 0.01), there was no difference in the rate of composite adverse perinatal outcome between the groups (7.74% vs. 8.65, p = 0.7). FIUVV is associated with growth restriction and congenital anomalies. A targeted anomaly scan and growth assessment are recommended. The overall perinatal outcome is similar to that of the normal fetal population. There is no evidence to support labour induction before 39 weeks.