Severe fetal anemia as a consequence of extra-abdominal umbilical vein varix: A case report and review of the literature.

Umbilical vein varix is associated with a high incidence of fetal anomalies and perinatal complications. There are two types of umbilical vein varix: fetal intra-abdominal and extra-abdominal. Herein, a case is reported of severe fetal anemia with extra-abdominal umbilical vein varix. A 33-year-old primigravida was referred to our hospital for fetal growth restriction, fetal cardiomegaly, and decreased fetal movements at 26 weeks' gestation. A Doppler assessment showed an elevated middle cerebral artery peak systolic velocity at 2.2 MoM, suggesting fetal anemia. Umbilical vein varix had caused intermittent turbulent flow, provoking hemolytic anemia. Intrauterine transfusion improved fetal circulatory failure and anemia and prolonged gestational period. At 33 weeks' gestation, the patient underwent cesarean delivery due to nonreassuring fetal status. Pathological analysis revealed focal loss of vascular smooth muscle of the umbilical vein. Extra-abdominal umbilical vein varix has been reported in 14 cases including this case. The antenatal diagnosis rate is reported to be 79%; fetal heartbeat abnormalities and fetal deaths were reported as 50% and 14%, respectively. Eighty-six percent of patients had intra-umbilical cord thrombosis, but currently this is the only case of hemolytic anemia. Furthermore, extra-abdominal umbilical vein varix may present as fetal hydrops with anemia. During ultrasound examination of fetal anemia, umbilical cord screening should be performed with caution.