33 - Neonatal necrotizing enterocolitis: clinical observations and pathophysiology

Summary

Establishment of appropriate enteral feedings in the premature infant is a frequent cause of concern in the neonatal intensive care unit due to the dreaded complication of neonatal necrotizing enterocolitis (NEC), an ischemic and inflammatory necrosis of bowel that results in significant mortality, longer lengths of stay, increased costs, and possibly increased risk for abnormal neurodevelopmental outcomes. The disease incidence varies between centers and across continents, but ranges between 3% and 28% with an average of approximately 8%–10% in infants born weighing less than 1500 g. Despite significant advances in neonatal care, the morbidity and mortality resulting from NEC has not improved over the last three decades, with recent reports of NEC mortality ranging between 10%–30%.

Clinical presentation

The disease presents clinically in premature neonates with variable symptoms of intestinal bleeding, emesis, abdominal distension, lethargy, and apnea and bradycardia, and signs of abdominal tenderness, thrombocytopenia, metabolic acidosis, tachycardia, respiratory failure, and, if severe, shock. The diagnosis is typically made by the identification of pneumatosis intestinalis (air in the bowel wall) on abdominal radiograph, although in some cases of NEC, commonly in un-fed patients, pneumatosis is not appreciated. In these situations, NEC may be diagnosed surgically or pathologically, or in some instances by ultrasound appreciation of portal venous air. Bell and colleagues suggested a classification scheme that differentiates feeding intolerance (stage I) from true NEC (stage II) and advanced NEC (stage III with peritonitis and/or perforation).