Neonatal Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is an acquired inflammatory bowel injury seen chiefly in preterm or critically ill neonates. It is not simply poor feed tolerance. In NEC, a vulnerable intestinal lining is injured, bacteria cross or proliferate within that damaged barrier, and enteral milk provides substrate within the bowel. The resulting inflammation can progress from mucosal injury to full-thickness necrosis. Prematurity creates the setting for this process. The immature bowel has less reserve to tolerate reduced perfusion, inflammation, and bacterial colonisation. A hypoxic or low-flow event can further compromise the intestinal mucosa. Once the barrier is disrupted, gas produced by bacteria may collect within the bowel wall, producing pneumatosis intestinalis. Gas may then enter portal venous circulation. If necrosis extends through the bowel wall, perforation releases intestinal contents into the peritoneal cavity and can rapidly lead to peritonitis, sepsis, and shock. The clinical danger is the speed of that transition. A mildly distended abdomen can become a surgical emergency within hours when bowel perfusion worsens or perforation occurs.