The prenatal diagnosis of isolated fetal varix of the intra-abdominal umbilical vein is associated with favorable neonatal outcome at term: a case series

Varix of the fetal intra-abdominal umbilical vein (VFIUV) has been reported to be associated with an increased risk of adverse perinatal outcome and especially with intra-uterine fetal demise (IUFD). Induction of preterm birth, as early as 32–34 weeks gestation has been suggested to minimize this risk. We aimed to evaluate our center experience with the antenatal diagnosis of VFIUV and review the relevant literature.

We identified 24 women with fetuses, with isolated VFIUV (excluding one lost-to-follow-up). GA at diagnosis was 30.5 ± 4.4 weeks; 13 (56.5 %) cases were diagnosed <32 weeks. The mean VFIUV diameter was 13 ± 2.9 (range 9–20) mm and turbulent flow was reported in 7 cases (30.4 %). GA at birth was 37 ± 2.5 weeks. The small for gestational age rate was 4 % (1/23), while no case of IUFD occurred. The group induction of labor rate was 65.2 %, while 43 % (10/23) due to the diagnosis of VFIUV alone: 17 % (4/23) preterm and 26 % (6/23) at term. The cesarean rate was 17 % (4/23) and NICU admission was required for five neonates (21.7 %). The preterm induction of birth was related to a significantly increased risk for cesarean and neonatal morbidity (p = 0.015; p = 0.029, respectively). The mode of delivery was not associated with the GA at diagnosis, size/type of flow of VFIUV (r = 0.101; r = 0.727; r = 0.671, respectively) overall (r) = 0.4. All fetuses were live-born with normal follow-up at 2–60 months.

Isolated VFIUV has a favorable perinatal outcome at term, unrelated to the structural and flow characteristics of VFIUV. We show that follow-up for growth abnormalities with no preterm induction of birth is a safe maternal and neonatal approach.