During the first 5–7 days of life, the umbilical vein can be catherized and used for central venous pressure monitoring. The umbilical vein leads to which of the following vessels?
(A) descending aorta
(B) ductus arteriosus
© ductus venosus
(D) inferior vena cava
(E) portal vein
explanation:
© In the fetus, the umbilical vein connects directly to the ductus venosus, a fetal vessel which bypasses the liver to bring oxygenated blood to the inferior vena cava (choice D). The descending aorta (choice A) distributes blood to the body and, in the fetal circulation, brings blood to the umbilical arteries by way of the iliac arteries for return to the placenta for oxygenation. The ductus arteriosus (choice B) is a fetal vessel which allows bypass of the oxygenated blood from the pulmonary trunk to the arch of the aorta. The portal vein (choice E) is formed by the union of the splenic vein and the superior mesenteric vein; it returns blood from the digestive system to the liver.