A 2-year-old girl with a history of chronic constipation since birth is brought to the emergency room because of nausea and vomiting. Physical examination shows marked abdominal distension. Abdominal radiography reveals distended bowel loops with a paucity of air in the rectum. A rectal biopsy shows an absence of ganglion cells. Which of the following is the most likely diagnosis?

Hirschsprung disease, also referred to as congenital megacolon, results from a congenital defect in the innervation of the large intestine, usually in the rectum. Severe chronic constipation is typical. Marked dilation of the colon occurs proximal to the stenotic rectum, with clinical signs of intestinal obstruction. The other choices are not associated with loss of ganglion cells.Diagnosis: Hirschsprung disease