Abstract This article evaluates a three-step screening approach for detecting portal system anomalies. All fetuses undergoing the mid-trimester anomaly scan, as well as referrals for suspected portal system anomalies, were prospectively screened for portal system anomalies at our tertiary hospital by two fetal medicine fellows (R.M. or A.K.) using the three-step protocol over a period of 2 years. The process included step 1: confirm a normal gallbladder to umbilical vein relationship (the curve), step 2: confirm the presence of a normal ductus venosus (DV) on color and spectral Doppler (the DV), and step 3: confirm the normal anatomy and direction of blood flow in the confluence of the portal sinus and the main portal vein (the X). All cases screened using the three-step protocol were surveyed in detail by one of the senior consultants (B.B. or M.B.). Portal system anomalies were then classified as described by Achiron et al. Over 2 years, 3,670 fetuses were screened for portal system anomalies using the three-step screening protocol. A total of 73 cases of portal system anomalies were diagnosed, which were: persistent right umbilical vein (n = 29), umbilical vein varix (n = 15), DV agenesis (n = 4), DV systemic shunt (n = 12), umbilical vein systemic shunt (n = 4), intrahepatic portosystemic shunts (IHPSS; n = 4), and unclassified variants (n = 5). All the diagnosed portal system anomalies showed at least one of the three steps to be abnormal, except one case of IHPSS. Thirty out of the 72 screen-positive fetuses (41%) showed the presence of a portal system anomaly associated with anomalies in other systems as well. Considering the ultrasound done by the senior consultants as the reference standard, the three-step protocol showed a sensitivity of 98.6% (95% confidence interval CI 92.6–100%) and a specificity of 100% (95% CI 99.9–100%). The three-step screening protocol is an effective and feasible method for screening fetuses for portal system anomalies. This protocol has the potential to be adopted as routine practice during the mid-trimester anomaly scan, as well as for evaluating the portal system in fetuses with multisystemic anomalies.
Balakrishnan et al. (2026) studied this question.