Necrotizing Enterocolitis (NEC)

Necrotizing enterocolitis is an inflammatory and ischaemic injury of the intestine that occurs most often in premature or very-low-birth-weight infants. The immature bowel has a fragile mucosal barrier, underdeveloped immune regulation, and less reliable perfusion. These vulnerabilities make it less able to tolerate a fall in blood flow or an exaggerated response to intestinal bacteria. NEC develops through the interaction of three conditions: intestinal ischaemia, abnormal bacterial colonisation, and enteral feeding substrate. Reduced perfusion injures the mucosa; bacteria then cross the damaged barrier and intensify inflammation. Feeding substrate can add to the workload and inflammatory process in an already injured bowel. Gas produced within the bowel wall appears as pneumatosis intestinalis. If injury progresses through the full thickness of the bowel, perforation, peritonitis, sepsis, and shock may follow. Prematurity and very low birth weight are the strongest background risks. Formula feeding is associated with greater risk than human milk, while human milk is preferred when enteral feeding is clinically appropriate. Other conditions that compromise perfusion or intestinal resilience, such as severe systemic illness, may further increase vulnerability. A risk factor...