Necrotizing enterocolitis

Necrotizing enterocolitis (NEC)

US – Hyperemic thickened bowel loops with thick echogenic mucosa.

NEC is an inflammatory gastrointestinal disease of unknown etiology with an incidence of 1-5% in the neonatal intensive care unit. Clinically, NEC is usually manifest by feeding intolerance, hematochezia, and/or abdominal distention and is difficult to distinguish from neonatal sepsis. Pathologic features resemble ischemic necrosis; initially there is mucosal inflammation which eventually extends transmural. The distal ileum and proximal colon are most often affected. Bowel perforation occurs in up to one-third of patients and is associated with bowel stricture, short gut syndrome, and peritonitis; mortality is high.

Radiography is most often used to diagnose NEC. Radiographic findings include ileus, focally dilated loops of bowel, separated loops of bowel, pneumatosis, portal venous gas and intraperitoneal gas. Ultrasound shows thickened bowel early and thin bowel later. Pneumatosis and portal gas can be demonstrated. Gaseous distention of bowel and peritoneal gas can limit US evaluation.

Doppler can also be helpful in the diagnosis. Bowel wall hyperemia corresponds to vasodilation and inflammatory changes. Absence of color Doppler flow is highly correlated with transmural necrosis.

Faingold R, et al. Necrotizing Enterocolitis: Assessment of Bowel Wall Viability with Color Doppler. Radiology (2005); 235:587-594.