A contrast enema is performed on a one-day-old infant presenting with bilious emesis and abdominal distension. Based on the findings, which of the following is the MOST likely diagnosis?

The examination shows a microcolon, which is a term applied to an unused colon; this happens in infants with congenital distal bowel obstruction. A. Patients with Hirschsprung disease should demonstrate a zone of transition between normal caliber colon distally, and dilated colon proximally. Such findings are not present in this case. B. Patients with meconium plug syndrome do not have a microcolon. The colon is normal in caliber, and demonstrates a large filling defect representing the meconium plug. C. There is microcolon with dilated proximal small bowel loops. Multiple filling defects are consistent with inspissated meconium. D. In patients with small left colon syndrome, the left colon and often poions of the sigmoid are small, similar to a microcolon; however, unlike the findings in the test case, the remainder of the colon, including the rectum, is normal in caliber. Therefore this answer is not correct.