[Solved]: A 2-day-old boy fails to pass meconium during the…

A 2-day-old boy fails to pass meconium during the first 48 hours of life. He was born at term to a healthy 19-year-old woman after an uncomplicated pregnancy. At birth, his weight was 3.9 kg (8.6 lb); currently, he weighs 3.8 kg (8.4 lb). His blood pressure is 70/50 mm Hg, pulse is 130/min, respirations are 33/min, and temperature is 37.0deg C (98.6deg F). On physical examination, he is fussy and appears mildly dehydrated. The bowel sounds are active on auscultation. His abdomen is mildly distended, and no masses can be identified on palpation. The patient’s anus is patent. An upper gastrointestinal study with oral contrast demonstrates normal anatomy. A lower gastrointestinal series with barium enema reveals a large amount of retained barium contrast within a dilated sigmoid colon and a normal-appearing rectum. The barium solution retention persists beyond 24 hours after administration. Which of the following best describes the cause of the patient’s symptoms? A. Failure of the neural crest cells to migrate caudally to the intestinal wall during embryogenesis B. Disruption of the apoptosis of the intestinal cells C. Hypertrophy of the muscular layer of the lower sigmoid colon D. Propelling of a polyp distally by peristalsis E. Decreased blood supply to the developing intestine in the embryonic period