Epidemiology and outcome of "early-onset" vs "late-onset" necrotizing enterocolitis

We hypothesized that among neonates with necrotizing enterocolitis (NEC), important epidemiologic and outcome differences exist between those with early-onset vs. those with late-onset NEC.

We reviewed all records of neonates cared for in the King Fahad University Hospital during the past ten years who had the diagnosis of NEC. We separated cases into two groups depending on age at diagnosis. Specifically, we termed "early-onset" those cases diagnosed during the first seven days of life, and "late-onset" those diagnosed thereafter. We compared, in the two groups, gestational age, clinical signs at onset, laboratory data, surgical findings, complications, and mortality.

From 1989 to 1999, 37 cases of stage IIa (or higher) NEC were diagnosed; 25 "early-onset" and 12 "late-onset". Neonates with "early-onset" NEC were more mature (35.4 +/- 2.5 weeks gestation) than those with "late-onset" (27.7 +/- 2.8 weeks, P=0.0001), were more likely to have feedings begun in the first 48 hours of life (P = 0.0002), and more likely to have feeding increments of >25 ml/kg/day (P=0.03). Neonates with "late-onset" NEC were more likely to present with vomiting (P=0.003) and apnea (P=0.001), and were more likely to have ileal rather than colonic necrotic lesions, short bowel syndrome, and mortality (P=0.03).

During the past 10 years at the King Fahad University Hospital, cases of early- and late-onset NEC have had distinct epidemiologic and outcome features. Recognizing these differences may be useful in prognostication and counseling.