In the fetal circulation, which structure allows oxygenated blood from the umbilical vein to bypass the hepatic sinusoids and enter the inferior vena cava directly?

• A Ductus venosus ✓
• B Foramen ovale
• C Ductus arteriosus
• D Umbilical arteriovenous anastomosis

Explanation

The ductus venosus is a fetal vascular shunt connecting the left branch of the portal vein directly to the inferior vena cava, allowing oxygenated blood from the umbilical vein to bypass about 50% of hepatic circulation. This preferentially delivers well-oxygenated blood towards the right heart and foramen ovale. After birth, the ductus venosus closes functionally within hours and anatomically within 1–3 weeks, becoming the ligamentum venosum.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.