Umbilical–portal–systemic venous shunt and fetal growth restriction: An Inquiry from a Prospective Study

BACKGROUND: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 retrospective small studies have reported a well-established association between umbilical-portal-systemic venous shunts and fetal growth restriction. However, the prevalence of portosystemic shunts in the fetal growth restricted population is yet to be determined. OBJECTIVES:The aims of this study were: 1. To determine the prevalence of fetal umbilical-portal-systemic venous shunts in pregnancies complicated by fetal growth restriction. 2. To compare the perinatal and neonatal outcome of fetal growth restriction pregnancies with and without umbilical-portal-systemic venous shunts. STUDY DESIGN:A prospective cross-sectional study of pregnancies diagnosed with fetal growth restriction, as defined by the Society for Maternal-Fetal Medicine fetal 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 fetal growth restriction pregnancies with and without umbilical-portal-systemic venous shunts were compared. RESULTS:One hundred and fifty cases of fetal growth restriction were recruited. The prevalence of umbilical-portal-systemic venous shunts in our cohort was 9.3% (n=14). Compared to the control group (fetal growth restriction without umbilical-portal-systemic venous shunts, n=136), the study group had a significantly lower mean gestational age at time of fetal growth restriction diagnosis [29.7 (±5.6) vs. 32.47 (±4.6) weeks of gestation, p=0.036] as well as an earlier gestational week at delivery [33.50 (±6.0) vs. 36.13 (±2.8), p=0.005]. The study group had a higher rate of fetal death (21.4% vs. 0.7%, p<0.001) and accordingly a lower rate of live births (71.4% vs. 95.6%, p=0.001). Associated additional fetal vascular anomalies were significantly more prevalent in the study group compared to controls (35.7% vs. 4.4%, respectively, p=<0.001). 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=0.011) and a higher rate of abnormal ductus venosus Doppler indices (64.3% vs. 23% p=0.001). There were no cases of hypertensive disorders of pregnancy in the study group compared to 12.5% in the control group (p=0.16). Other perinatal and neonatal outcomes were comparable. CONCLUSIONS:Umbilical-portal-systemic venous shunt is a relatively common finding in growth restricted fetuses. Compared to fetal growth restriction pregnancies with a normal portal system, these pregnancies complicated by FGR and umbilical-portal-systemic venous shunt are associated with different Doppler flow pattern, increased risk for fetal death, earlier presentation of fetal growth restriction, 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 fetal growth restriction, as umbilical-portal-systemic venous shunts may have implications on perinatal outcome.