CVS Practice Test 2025 – Complete Exam Preparation

The ductus venosus plays a critical role in fetal circulation, acting as a shunt that allows roughly 50% of the oxygen-rich blood from the placenta to bypass the liver and flow directly into the inferior vena cava. This pathway is vital for ensuring that the developing fetus receives an adequate supply of oxygen and nutrients while minimizing the workload on the liver, which is not fully functional during prenatal development.

Understanding the function of the ductus venosus helps clarify its importance in facilitating efficient circulation in a fetus where oxygen supply comes from maternal blood rather than the lungs. Once the baby is born and begins to breathe independently, this structure typically closes and becomes the ligamentum venosum, marking a transition to the postnatal circulation where the liver plays a more integral role in metabolism and detoxification.

Other structures mentioned have distinct functions: the ductus arteriosus is involved in shunting blood from the pulmonary artery to the aorta; the foramen ovale allows blood to flow from the right atrium to the left atrium; and the pulmonary veins carry oxygenated blood from the lungs to the heart. Each of these plays critical roles in fetal development, but none replicate the specific function of the ductus venosus in