Ileal atresia with meconium peritonitis: fetal MRI evaluation.

We report a case of ileal atresia with meconium peritonitis evaluated by fetal MRI. Prenatal ultrasounds in the third trimester initially demonstrated a cystic abdominal mass that resolved with development of dilated bowel loops. Fetal MRI at 32 weeks gestation identified a perihepatic collection with several dilated small bowel loops and normal sized meconium filled rectosigmoid consistent with distal bowel perforation and loculated meconium peritonitis. Following delivery, the infant presented with bowel obstruction. Contrast enema revealed a normal sized rectosigmoid with small ascending and transverse colon. A distal ileal atresia type IIIa was documented at surgery.