**Question:** 3-month infants with abdominal palpable mass & non-bilious vomiting –

A. Intestinal obstruction
B. Meconium ileus
C. Hydronephrosis
D. Hepatocele

**Correct Answer:** B. Meconium ileus

**Core Concept:**
Meconium is the sticky, dark green substance that passes from the newborn infant's bowel during the first stool after birth. In some infants, particularly those with cystic fibrosis (CF), meconium accumulates in the distal small bowel and colon, leading to meconium ileus. This condition presents with abdominal distension, non-bilious vomiting, and a palpable abdominal mass.

**Why the Correct Answer is Right:**
Meconium ileus is a specific presentation of cystic fibrosis (CF) in infants, a genetic disorder characterized by the production of thick and sticky mucus. In the context of meconium ileus, thick mucus obstructs the distal small bowel and colon, causing abdominal distension and non-bilious vomiting. The palpable abdominal mass is due to the mass effect from the accumulated meconium.

**Why Each Wrong Option is Incorrect:**

A. Intestinal obstruction: This term refers to any obstruction in the gastrointestinal tract, not specifically related to meconium accumulation. Meconium ileus is the correct answer as it is a specific presentation of cystic fibrosis.

B. Meconium ileus: This is the correct answer, as explained above.

C. Hydronephrosis: This refers to the swelling of the renal pelvis and ureter due to urine retention, not related to meconium accumulation or abdominal symptoms in infants.

D. Hepatocele: This is a hernia of the liver through an inguinal canal, unrelated to meconium accumulation and presenting symptoms in infants.

**Clinical Pearl:**
Cystic fibrosis is a systemic disease affecting multiple organs, including the lungs, pancreas, and genitourinary system. However, meconium ileus is a specific presentation of cystic fibrosis that should be considered in infants with abdominal symptoms like non-bilious vomiting and a palpable abdominal mass.

Understanding the underlying causes, symptoms, and appropriate treatments for such conditions is crucial for diagnosing and managing pediatric patients effectively. Always refer to the correct terminology and specific presentations when discussing pediatric diseases to ensure accurate diagnosis and treatment planning.