Complex sentence: In adult-hood, there remain small paraumbilical veins in the substance of the ligament, which act as an important portacaval anastomosis in severe portal hypertension, resulting in a caput medusae presentation.
Split into simpler sentences: In adult-hood, small paraumbilical veins remain in the substance of the ligament. These act as an important portacaval anastomosis in severe portal hypertension, resulting in a caput medusae presentation.