Meconium ileus is most commonly associated with which condition?

• A. Cystic fibrosis
• B. Crohn's disease
• C. Hirschsprung disease
• D. Ulcerative colitis

Answer: (A)

Meconium ileus occurs when thick, inspissated meconium blocks the ileum in a newborn. This finding is classic for cystic fibrosis, because the CFTR mutation leads to abnormal chloride transport and reduced water content in the intestinal secretions, producing very thick mucus that plugs the distal small intestine at birth. Because of this strong link, a newborn with meconium ileus is routinely evaluated for CF. Other conditions like Hirschsprung disease cause neonatal obstruction from a different mechanism—absence of enteric nerves leading to functional obstruction—not thick meconium. Crohn’s disease and ulcerative colitis are inflammatory bowel diseases typically presenting later in life, not as a neonatal ileal obstruction.