What connects the umbilical vein to the inferior vena cava?

The connection between the umbilical vein and the inferior vena cava is known as the ductus venosus. This structure plays a crucial role in fetal circulation. The umbilical vein carries oxygenated blood from the placenta to the fetus, and the ductus venosus serves as a bypass that allows a portion of this blood to flow directly into the inferior vena cava. This mechanism is important because it enables the oxygen-rich blood to reach the right atrium of the heart more efficiently, where it can be distributed to the developing organs and tissues of the fetus.

In contrast, the ductus arteriosus is a vessel that connects the pulmonary artery to the aorta, facilitating blood flow in fetal life and is involved in bypassing the lungs. The umbilical cord contains the umbilical vein and arteries but does not serve as a connection to the inferior vena cava. The foramen ovale is an opening between the right and left atria of the heart that allows blood to bypass the non-functioning fetal lungs, but it is not responsible for connecting the umbilical vein to the inferior vena cava.