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Necrotizing Enterocolitis (NEC)


William J. Cochran

, MD, Geisinger Clinic

Last full review/revision May 2020| Content last modified May 2020
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Necrotizing enterocolitis is injury to the inner surface of the intestine. This disorder occurs most often in newborns who are premature and/or seriously ill.

  • The abdomen may be swollen, stools may be bloody, and the newborn may vomit a greenish, yellow, or rust-colored fluid and appear very sick and sluggish.

  • The diagnosis is confirmed by abdominal x-rays.

  • About 70 to 80% of newborns with this disorder survive.

  • Treatment involves stopping feedings, passing a suction tube into the stomach to remove stomach contents to relieve pressure, and giving antibiotics and fluids by vein (intravenously).

  • In severe cases, surgery is required to remove the damaged intestine.

Over 90% of cases of necrotizing enterocolitis occur in premature newborns. Necrotizing enterocolitis may occur in clusters or as outbreaks in neonatal intensive care units (NICUs). Sometimes these outbreaks can be linked to specific bacteria (such as E. coli), but often the cause is not known.

The cause of necrotizing enterocolitis is not completely understood, but it is in part related to immaturity of the intestine along with low oxygen levels in the blood and/or diminished blood flow to the intestine. Diminished blood flow to the intestine in a sick premature newborn may result in injury to the inner surface of the intestine. The injury allows bacteria that normally exist within the intestine to invade the damaged intestinal wall and then enter the newborn’s bloodstream, causing infection (sepsis). If the injury progresses through the entire thickness of the intestinal wall and the intestinal wall tears (perforates), intestinal contents leak into the abdominal cavity and cause inflammation and usually infection of the abdominal cavity and its lining (peritonitis).

Risk factors

In addition to prematurity, other risk factors include

  • Prelabor rupture of the membranes (the mother's water breaks more than 12 hours before labor begins): The leaking amniotic fluid can lead to an infection in the fetus.

  • Disturbance of the bacteria that live in the digestive system: Treatment with antibiotics or acid-suppressing drugs can encourage growth of potentially harmful bacteria that may penetrate the intestine.

  • Perinatal asphyxia: This disorder involves a decrease in blood flow to the newborn's tissues or a decrease in oxygen in the newborn's blood before, during, or just after delivery.

  • Heart disease present at birth (congenital heart disease): Birth defects of the heart may affect the way blood flows or affect the levels of oxygen in the blood.

  • Anemia (low number of red blood cells): In anemia, it can be difficult for a newborn's blood to carry an adequate supply of oxygen.

  • Exchange transfusions: During this procedure, the newborn's blood is removed and replaced, which may affect blood flow to the organs.

  • Formula feeding: Breast milk contains substances that help protect the walls of the digestive tract that formulas do not have.

Symptoms of NEC

Newborns with necrotizing enterocolitis may develop swelling of the abdomen and may have difficulty feeding. They may vomit bloody or green- or yellow-stained fluid, and blood may be visible in the stools. These newborns soon appear very sick and sluggish (lethargic) and have a low body temperature and repeated pauses of breathing (apnea).

Diagnosis of NEC

  • X-rays of the abdomen

  • Ultrasonography

  • Blood tests

The diagnosis of necrotizing enterocolitis is confirmed by abdominal x-rays that show gas in the intestinal wall (called pneumatosis intestinalis) or that free air is in the abdominal cavity if the intestinal wall has perforated. Doctors may also do an ultrasound of the abdomen to look at the thickness of the intestinal wall, pneumatosis intestinalis, and blood flow.

Blood samples are taken to look for bacteria and other abnormalities (for example, a high white blood cell count).

Prognosis of NEC

Current medical and surgical treatments have improved the prognosis for infants with necrotizing enterocolitis. About 70 to 80% of affected newborns survive. Narrowing of the intestine (intestinal stricture) is the most common long-term complication. Strictures occur in 10 to 36% of infants who survive the initial episode of necrotizing enterocolitis. Strictures typically cause symptoms 2 to 3 months after the episode of necrotizing enterocolitis. Sometimes strictures need to be corrected surgically.

Prevention of NEC

Feeding premature newborns their mother’s breast milk rather than formula seems to provide some protection against necrotizing enterocolitis. In addition, hospital personnel avoid giving the infant highly concentrated formula and take measures to prevent low oxygen levels in the infant's bloodstream. Antibiotics and acid-supressing drugs also should be avoided when possible.

There is some evidence that probiotics (good bacteria) may be helpful in prevention, but this therapy is still experimental. Pregnant women who are at risk of having a preterm birth may be given corticosteroids to help prevent necrotizing enterocolitis.

Treatment of NEC

  • Nutrition and fluids given by vein

  • Sometimes surgery

Newborns who have necrotizing enterocolitis remain in the hospital and are treated in the neonatal intensive care unit (NICU).

Feedings are stopped in newborns with necrotizing enterocolitis. A suction tube is passed into the newborn's stomach to remove its contents, which decreases pressure and helps prevent vomiting. Nutrition and fluids are given by vein to maintain hydration and nutrition and allow the intestine to heal. Antibiotics are given by vein to treat infection.

Over 75% of newborns with necrotizing enterocolitis do not need surgery. However, surgery is needed if there is intestinal perforation or part of the intestine is severely affected. The surgery involves removing the part of the intestine that has not been receiving enough blood. The ends of the healthy intestine are brought out to the skin surface to create a temporary opening to allow the intestines to drain (ostomy). Later, when the infant is healthy, the ends of the intestine are reattached and the intestine is put back into the abdominal cavity.

In extremely small (about 1 pound or less, or less than 600 grams) or seriously ill infants who may not survive more extensive surgery, doctors may place peritoneal drains into the abdominal cavity. Peritoneal drains allow the infected material in the abdomen to drain out of the body and may lessen symptoms. The procedure helps stabilize these infants so that an operation can be done at a later time when they are in less critical condition. In some cases, infants recover without needing additional surgery.

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