Indications for operation in necrotizing enterocolitis revisited

Operation for necrotizing enterocolitis (NEC) is reserved for infants with intestinal gangrene or perforation. It should not be undertaken until gangrene is present, but ideally should be performed before intestinal perforation occurs. To characterize the onset of intestinal gangrene, data were analyzed for 147 infants with documented NEC, 94 of whom had gangrene. Twelve criteria were evaluated as predictors of intestinal gangrene, using standard epidemiological measures for diagnostic tests. Sensitivity, specificity, positive predictive value, negative predictive value, and prevalence were calculated for each of the proposed operative criteria. The best indications were those whose specificity and positive predictive value approached 100%, and whose prevalence was greater than 10%. These were pneumoperitoneum, positive paracentesis, and portal venous gas. Good indications were those whose specificity and positive predictive value approached 100%, but whose prevalence was less than 10%. These were fixed intestinal loop noted on x-ray, erythema of the abdominal wall, and a palpable abdominal mass. A fair indication for operation--with 91% specificity, 94% positive predictive value, and prevalence of 20%--was "severe" pneumatosis intestinalis, graded by a radiographic system. Poorer indications for operation (and their predictive value for the presence of gangrene) were clinical deterioration (78%), platelet count below 100,000/mm3 (73%), abdominal tenderness (58%), severe gastrointestinal hemorrhage (50%), and gasless abdomen with ascites (0%). No test had a high sensitivity for intestinal gangrene. Portal venous gas should be acknowledged as an indication for operation. Probability analysis may provide a more scientific basis for clinical decision-making.