Review Question - QID 108776

The most likely diagnosis in this child is a patent urachus. This condition presents with urine discharge from the umbilicus following birth.

In this newborn child, the presence of urine discharge from the umbilicus is highly specific for a urachal duct abnormality. The urachus is an embryonic structure that arises from the allantois, a protrusion of the yolk sac through the umbilicus that develops during the third week of gestation. The urachus functions to connect the fetal bladder to the yolk sac. It normally obliterates during the 12th week of gestation and becomes the median umbilical ligament. If the urachus fails to obliterate, a persistent communication will exist between the bladder and the umbilicus, resulting in urine discharge from the umbilical stump at birth.

Incorrect Answers:
Answer 1: The omphalomesenteric duct (vitelline duct) is a fetal structure that connects the midgut lumen to the yolk sac in the developing embryo. If the omphalomesenteric duct fails to obliterate during the seventh week of embryologic development, a Meckel’s diverticulum may develop.

Answer 2: The umbilical vein functions to transport oxygenated blood from the placenta to the fetal circulation. It obliterates soon after birth and is replaced by the round ligament of the liver.

Answer 3: The paramesonephric duct (Mullerian duct) eventually develops into the female internal reproductive organs (uterus, fallopian tubes, and inner vagina).

Answer 5: The ductus venosus is a fetal structure that joins the left portal vein to the left hepatic vein. The ligamentum venosum is the fibrous remnant of the ductus venosus. It courses along the posterior aspect of the liver.

Bullet Summary:
The urachus is a channel between the fetal bladder and umbilicus that allows urine to drain during the first trimester of pregnancy. If the urachus fails to obliterate, a patent urachus will lead to urine drainage from the umbilicus at birth.