Background/Purpose The purpose of this study was to determine whether a correlation exists between the finding of complex ascites on ultrasound (US) and the presence of intestinal perforation or gangrene in neonates with complicated necrotizing enterocolitis (NEC). Methods Charts of neonates with NEC (n = 76) whose care involved consultations with the pediatric surgery service between 2005 and 2008 were reviewed. Twenty-three babies with NEC without free air had a bedside abdominal US. Neonates with pneumoperitoneum were excluded from the study because this was an absolute indication for surgical intervention. Results Twelve of the 23 neonates who had a bedside abdominal US were found to have ascites with debris or complex ascites. One of these 12 patients improved with medical management, and the ascites resolved. One infant with complex ascites had an initial laparotomy that revealed extensive bowel necrosis and gangrene that required intestinal resection and ostomy creation. This infant survived and is currently doing well. Ten patients were critically ill and were managed with bedside peritoneal drainage. Of those, 7 had drainage of intestinal contents after placement of the drain. Two of the babies who had a drain placed for complex ascites subsequently died of progressive disease. Five neonates with ascites with debris improved after peritoneal drainage and were subsequently subjected to laparotomy. All had gangrene with intestinal perforation. Three infants with complex ascites and intestinal contents were not observed during the initial peritoneal drainage. They improved after peritoneal drainage and had laparotomy. Free intestinal perforation was not demonstrated. The 3 infants in this group survived. Conclusions The presence of complex ascites with debris correlated well with intestinal gangrene or perforation. This correlation may also be a predictor of mortality. Neonates with complicated NEC without clear indication for surgical intervention would benefit from bedside abdominal US evaluation.