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.
Abdominal X-rays are done frequently if NEC is suspected. These films will show the neonatal team if there are any fixed or distended loops of bowel that may indicate an ileus (obstruction). Pneumatosis intestinalis (air in the bowel wall) can be seen early in NEC and can resolve over a number of hours. Pneumoperitoneum (air in the abdomen) is an indicator for immediate surgery. Air in the abdomen shows that the bowel has perforated (torn).
Medical management consists of stopping feeds, nasogastric drainage to suction (tube in baby’s 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.
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 a colostomy 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.
Having a baby with NEC is confusing and frightening. Feeding your child is a basic bonding parental experience and a child that can’t 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.
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