Umbilical-portal-systemic venous shunt and intrauterine growth restriction: an inquiry from a prospective study

The investigation of the fetal umbilical-portal venous system is based on the premise that congenital anomalies of this system may be related to adverse perinatal outcomes. Several small retrospective studies have reported an association between umbilical-portal-systemic venous shunts and intrauterine growth restriction. However, the prevalence of portosystemic shunts in the fetal growth restricted population is yet to be determined.

The aims of this study were (1) to determine the prevalence of fetal umbilical-portal-systemic venous shunts in pregnancies complicated by intrauterine growth restriction and (2) to compare the perinatal and neonatal outcomes of pregnancies with intrauterine growth restriction with and without umbilical-portal-systemic venous shunts.

This was a prospective, cross-sectional study of pregnancies diagnosed with intrauterine growth restriction, as defined by the Society for Maternal-Fetal Medicine intrauterine growth restriction guidelines. All participants underwent a detailed anomaly scan, supplemented with a targeted scan of the fetal portal system. Venous shunts were diagnosed using color Doppler mode. The perinatal outcomes of pregnancies with intrauterine growth restriction with and without umbilical-portal-systemic venous shunts were compared.

A total of 150 cases with intrauterine growth restriction were recruited. The prevalence of umbilical-portal-systemic venous shunts in our cohort was 9.3% (n=14). When compared with the control group (intrauterine growth restriction without umbilical-portal-systemic venous shunts, n=136), the study group had a significantly lower mean gestational age at the time of intrauterine growth restriction diagnosis (29.7±5.6 vs 32.47±4.6 weeks of gestation; P=.036) and an earlier gestational age at delivery (33.50±6.0 vs 36.13±2.8; P=.005). The study group had a higher rate of fetal death (21.4% vs 0.7%; P<.001) and, accordingly, a lower rate of live births (71.4% vs 95.6%; P=.001). Additional associated fetal vascular anomalies were significantly more prevalent in the study group than in the control group (35.7% vs 4.4%; P≤.001). The rate of other associated anomalies was similar. The study group had a significantly lower rate of abnormal uterine artery Doppler indices (0% vs 40.4%; P=.011) and a higher rate of abnormal ductus venosus Doppler indices (64.3% vs 23%; P=.001). There were no cases of hypertensive disorders of pregnancy in the study group, whereas the control group had an incidence of 12.5% (P=.16). Other perinatal and neonatal outcomes were comparable.

Umbilical-portal-systemic venous shunt is a relatively common finding among fetuses with growth restriction. When compared with pregnancies with intrauterine growth restriction with a normal portal system, these pregnancies complicated by intrauterine growth restriction and an umbilical-portal-systemic venous shunt are associated with a different Doppler flow pattern, an increased risk for fetal death, earlier presentation of intrauterine growth restriction, a lower gestational age at delivery, additional congenital vascular anomalies, and a lower rate of pregnancy-induced hypertensive disorders. Meticulous sonographic evaluation of the portal system should be considered in the prenatal workup of intrauterine growth restriction, as umbilical-portal-systemic venous shunts may affect perinatal outcomes.