Necrotizing enterocolitis (NEC) is a serious intestinal disease that mostly affects premature babies. It occurs when the tissue lining an infants intestine becomes diseased and can die, and the bacteria in the infants intestine can then penetrate the dead or decaying intestinal tissue, infect the wall of the intestine, and enter the bloodstream, causing systemic or bloodstream infection. The exact cause of NEC is still unknown, but experts believe that an underdeveloped (premature) intestine, too little oxygen or blood flow to the intestine at birth or later, and injury to the intestinal lining might play a role. Symptoms of NEC can vary from baby to baby, and can be like those caused by other digestive problems. Commonly reported symptoms include poor tolerance of feeding, bloating or swelling of the stomach, abdominal tenderness, vomiting, lethargy, and diarrhea with bloody stool. NEC typically develops within the first 2 weeks of life in a premature infant who is being fed with formula as opposed to breast milk. Most babies who develop NEC recover fully and do not have further feeding problems. However, in some cases, the intestine may be scarred, narrowed, or blocked, and more surgery might be needed. Malabsorption (when the intestine cant absorb nutrients normally) can be a lasting problem from NEC, and a baby with malabsorption may need nutrition delivered directly into a vein until the intestine heals well enough to tolerate feeding.