A male newborn is delivered at term to a 30-year-old woman. Pregnancy and delivery were uncomplicated. At birth, the umbilical cord is noted to be large. When the newborn cries, straw-colored fluid leaks from the umbilicus. The external genitalia appear normal. Which of the following is the most likely cause of this newborn's symptoms? A Abnormal fusion of the urethral folds B Failed closure of the vitelline duct C Failed obliteration of an allantoic remnant D Infection of the umbilical cord stump E Incomplete closure of the lateral folds F Malformation of the medial umbilical ligament
C:-Failed obliteration of the urachus, an allantoic remnant, is the most likely cause of this newborn's symptoms. The urachus is an embryonic structure that allows free communication between the bladder and yolk sac, facilitating early drainage of the urinary bladder. It normally involutes in utero to form the median umbilical ligament. Failure of involution results in congenital urachal abnormalities, including patent urachus, in which urine flowing through the still open urachus causes swelling of and leakage from the umbilicus, as seen here.
