What is meconium ileus?

• A. A bowel obstruction caused by thick, sticky meconium blocking the ileum; most infants with meconium ileus have cystic fibrosis
• B. A colon obstruction due to stool buildup in adults
• C. An intestinal malrotation presenting with bilious vomiting
• D. A blockage of the stomach due to pyloric stenosis

Answer: (A)

Meconium ileus is a neonatal intestinal obstruction caused by inspissated, thick, sticky meconium blocking the ileum. In babies with cystic fibrosis, thick mucus leads to meconium that is difficult to evacuate, causing a blockage in the distal small intestine soon after birth. Clinically, this presents with abdominal distension and bilious vomiting and failure to pass meconium in the first days of life. Imaging can show a characteristic gas-filled bowel with a soap-bubble pattern, and contrast enema may reveal a microcolon with meconium plugs. Treatment often starts with a hyperosmolar enema (such as Gastrografin) to dissolve the obstruction, with surgical intervention if needed. The strong link to cystic fibrosis explains why this condition is typically described as a bowel obstruction caused by thick, sticky meconium blocking the ileum, seen in infancy. Other options describe different age groups or parts of the GI tract (adult stool buildup, malrotation, or pyloric stenosis) and do not match this neonatal ileal obstruction.