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

Step 1: Know the normal timeline.
About 90% of full-term babies pass their first stool, meconium, within 24 hours of birth, and almost all do so by 48 hours. Delay past this point is a red flag for a bowel problem.

Step 2: Note that the baby looks normal outside.
The question says there is no obvious external abnormality. This rules out anal atresia, since that condition is seen right away on the first exam as an absent or malformed anal opening.

Step 3: Think about what blocks stool from passing with a normal-looking anus.
Congenital aganglionosis, better known as Hirschsprung disease, happens when nerve cells (ganglion cells) fail to develop in the last part of the colon. That segment cannot relax, so it stays tightly contracted and blocks stool from moving through, even though the anus itself looks completely normal.

Step 4: Rule out the other choices.
Congenital pouch colon is a rare defect that comes together with an anorectal malformation, so the anus would not be normal. Meconium ileus, seen mostly in cystic fibrosis, blocks the small bowel and usually shows up with distension and vomiting soon after birth, and it is a less common overall cause of delayed meconium than Hirschsprung disease.

Final Answer:
Delayed meconium beyond 48 hours with a normal-looking anus is the classic presentation of Hirschsprung disease.
\[ \boxed{\text{Congenital aganglionosis (Hirschsprung disease)}} \]