Two Rare Variants of Partial Portal System Agenesis Involved Fetal Portal Sinus Without Porto-Systemic Shunt

Background & Objectives: Congenital partial agenesis of the portal venous system is a very rare anomaly in which part of the portal blood bypass the liver, and is usually associated with the portosystemic shunt (PSS). The prognosis is good and they usually have excellent hemodynamic status with normal fetal growth and a survival rate. Case report: In this study, we report two rare cases of fetal portal system anomalies at second trimester which mainly involved portal sinus. They are the first cases that have ever been reported without any systemic shunt. Both fetuses were born normally and have had normal outcomes ever since. Conclusion: Partial portal system agenesis with only minor changes in portal system anatomy and without PSS can be considered as variants of portal system with good outcome.