Delayed Presentation of Meconium Ileus in an Infant With Cystic Fibrosis.

Although infants with meconium ileus usually present with apparent symptoms shortly after birth, the diagnosis of meconium ileus and cystic fibrosis (CF) may be delayed, awaiting newborn screening (NBS) results. We present the case of an 11-day-old term girl with delayed passage of meconium at 48 hours who had 2 subsequent small meconium stools over the following week. There was a normal feeding history and no signs of abdominal distension or distress. She then presented with an acute abdomen, decompensated shock, bowel perforation, and peritonitis, requiring multiple intestinal surgeries. Her NBS for CF was positive, and CF was ultimately confirmed with mutation analysis. Her course was complicated by prolonged parenteral feedings and mechanical ventilation via tracheostomy. The infant was managed with soy oil, medium chain triglycerides, olive oil, fish oil lipids and experienced only transaminitis without cholestasis and no chronic liver sequelae, with subsequent normalization of her transaminases without treatment. Because her only symptom was decreased stool output and NBS results were unavailable, the CF diagnosis was delayed until she presented in extremis. Delayed meconium passage and decreased stool output during the first week of life should lead to suspicion and additional evaluation for CF while awaiting NBS results. Careful monitoring is indicated to prevent serious, life-threatening complications. The use of soy oil, medium chain triglycerides, olive oil, fish oil lipids for infants requiring prolonged parenteral nutrition may also be considered proactively to prevent cholestasis, particularly for high risk groups.