A 3-day-old full-term neonate passes no meconium and has progressive abdominal distension with vomiting. There is no family history of cystic fibrosis. Abdominal X-ray shows multiple dilated loops with a soap bubble appearance in the right lower quadrant. Contrast enema reveals a microcolon. Sweat chloride testing later confirms the diagnosis. What was the cause of the obstruction?

• A Inspissated meconium obstructing the terminal ileum due to deficient pancreatic enzymes ✓
• B Jejunal atresia secondary to intrauterine vascular accident
• C Colonic aganglionosis extending proximally from the anal canal
• D Meconium plug syndrome caused by immature colonic motility

Explanation

Meconium ileus results from thick, tenacious meconium in the terminal ileum caused by abnormal secretions and pancreatic enzyme deficiency in cystic fibrosis, giving a microcolon on enema because unused colon is small caliber. B water-soluble contrast enema such as Gastrografin is both diagnostic and often therapeutic by hydrating and lubricating the inspissated meconium. Jejunal atresia gives a microcolon too but is not linked to cystic fibrosis, and Hirschsprung disease produces a transition zone rather than a microcolon with soap bubbles.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.