Question

Failure to pass meconium within 48 hours of birth in a newborn with no obvious external abnormality should raise suspicion of:

• A. Anal atresia
• B. Congenital pouch colon
• C. Congenital aganglionosis
• D. Meconium ileus

Hint:

Normal-looking anus plus no meconium by 48 hours points to Hirschsprung disease (aganglionosis).

Answer 1

The Correct Option is C

Normal newborns pass meconium within 24 to 48 hours. When that does not happen and the baby's outside anatomy looks normal, the question is asking which inside problem is most likely.

1. Anal atresia: this shows up on the very first check as a missing or blocked anal opening, so it does not fit a baby with no external abnormality.
2. Congenital pouch colon: this rare condition comes together with an anorectal malformation, so again the outside exam would not be normal.
3. Congenital aganglionosis: nerve cells are missing from the end of the colon, so that segment cannot relax and stool backs up behind it. The anus and the outside of the baby look completely normal because the defect is inside the bowel wall, not in the anatomy of the anus.
4. Meconium ileus: this blocks the small bowel, mostly in babies with cystic fibrosis, and tends to show early distension and bilious vomiting rather than being the first cause considered for simple delayed meconium.

Since the baby looks normal outside, the block has to be a functional one inside the bowel, and that is exactly what happens in Hirschsprung disease.

Let's summarize:

• Delayed meconium past 48 hours with a normal anus points to a nerve cell problem in the colon.
• Anal atresia and pouch colon are ruled out because they change how the anus looks.

So congenital aganglionosis (Hirschsprung disease) is the right answer.