**Question:** A newborn presenting with intestinal obstruction showed on abdominal X-ray, multiple air-fluid levels. The diagnosis is not likely to be –

A. Intussusception
B. Meconium ileus
C. Hirschsprung's disease
D. Meconium plug syndrome

**Correct Answer:** D. Meconium plug syndrome

**Core Concept:**
Meconium plug syndrome (MPS) is a rare cause of neonatal intestinal obstruction, characterized by the formation of a thick, sticky mass of meconium (intestinal secretions) within the gastrointestinal tract. This can lead to intestinal obstruction, with radiological findings of multiple air-fluid levels on abdominal X-ray.

**Why the Correct Answer is Right:**
In MPS, the meconium plug obstructs the intestinal lumen, causing multiple air-fluid levels on abdominal X-ray. This diagnosis is unlikely in the context of the given question because:

1. Intussusception typically presents with a "target sign" on X-ray, representing the telescoping of one portion of intestine within another.
2. Meconium ileus (option B) often presents with a "target sign" as well, but it is more commonly associated with cystic fibrosis.
3. Hirschsprung's disease (option C) is characterized by a complete absence of ganglion cells in the rectosigmoid colon, leading to a "flail segment" on X-ray instead of multiple air-fluid levels.

**Why Each Wrong Option is Incorrect:**
A. Intussusception: Multiple air-fluid levels due to telescoping of intestine
B. Meconium ileus (cystic fibrosis): Multiple air-fluid levels on X-ray
C. Hirschsprung's disease: "Flail segment" on X-ray due to absence of ganglion cells
D. Meconium plug syndrome: Multiple air-fluid levels on X-ray, ruling out the other options

**Clinical Pearl:**
Meconium plug syndrome is a rare cause of neonatal intestinal obstruction. It is often associated with meconium peritonitis, which can lead to sepsis and even death if not promptly diagnosed and treated. Early clinical suspicion and timely intervention are crucial to manage this condition effectively.