The disease has diverse clinical manifestations, ranging from a relatively mild course characterized by feeding intolerance, abdominal distension, hematochezia, and vomiting to a more fulminant course characterized by intestinal necrosis, perforation, sepsis, and death. Newborns may initially display abdominal distension and marked gastric residual fluid or vomiting. Occultly positive for blood or grossly bloody stools may be present. Frequently, affected infants have nonspecific signs and symptoms of sepsis. The initial findings from the physical examination are nonspecific, but as the disease progresses, the abdomen becomes firm and discolored, and visible loops of bowel are seen.