What is Necrotizing Enterocolitis (NEC)?
Necrotizing enterocolitis (NEC) affects mainly premature babies. It is the most common surgical emergency in newborns. NEC accounts for 15% of deaths in premature babies weighing less than 1500 grams. Overall death from those babies with NEC is 25%.
What causes NEC?
No single factor has been established as the cause of NEC. It is now thought that NEC is the result of a combination of several factors. The two consistent findings are prematurity and feedings. The premature intestine reacts abnormally and develops an acute inflammatory response to feedings leading to intestinal necrosis (death). Some postnatal issues including heart abnormalities, obstruction of circulation in the bowel, infection or gastroschisis are also associated with NEC.
In the premature infant, NEC usually occurs a week to ten days after the initiation of feedings. In the term baby, NEC occurs within one to four days of life if feeding is started on day one. The risk of NEC is less with later gestational age. Very few unfed infants develop NEC. One theory which connects feeding to bowel mucosa damage involves the overgrowth of bacteria when provided with a carbohydrate source. The digestion of the lactose in formula by premature infant is incomplete and the residual ferments (has a chemical change) that encourages growth of bacteria that cause inflammation.
What are the signs and symptoms of NEC?
NEC is difficult to diagnose. The baby may have lethargy, poor feeding, bilious vomiting, distended abdomen and blood in stools. Physical examination may show the baby to have abdominal tenderness, periumbilical darkening or erythema (redness, or a fixed loop of bowel that can be felt.
How is NEC managed?
Medical management consists of stopping feeds, nasogastric drainage to suction (tube in babys stomach to "suck out" contents), 7-14 days of antibiotics and IV nutrition. Close monitoring of fluid status, electrolytes, coagulation and oxygen requirements are also necessary. 60-80% of babies with NEC are managed medically and symptoms resolve without surgery. Feedings postoperatively are started slowly.
What if surgery is needed?
Surgery is necessary if medical management fails or the bowel is perforated (torn). After opening the abdomen, the surgeon may find a swollen, purple bowel with areas of necrosed (dead) bowel. The usual areas involved are the terminal ileum, cecum and right colon but the whole bowel may be involved. The goal is to remove only that bowel that is fully necrosed (dead) and to leave any marginal areas in the hope that they will survive. This may require an ostomy and/or another operation within 24-48 hours to evaluate any surviving bowel. The nutritional outcome is roughly based on the remaining intestinal length and the medical and surgical team will discuss this with you.
A note to parents
Having a baby with NEC is confusing and frightening. Feeding your child is a basic bonding parental experience and a child that cant be fed probably makes you feel helpless and frustrated. We know that soul searching is inevitable with questions like "What did we do wrong?" The frustration and anxiety are increased with the realization that there is nothing to do but "wait and watch". Your nurse and any other members of the team are here to help you. Ask questions. We are here to support you through this difficult time.