What is NEC?

Necrotizing enterocolitis (NEC) is an intestinal disease that primarily affects premature and medically fragile infants. NEC causes an inflammatory process that can lead to intestinal tissue damage.

Every year in the US, thousands of babies develop NEC and hundreds of these babies die from this complex intestinal condition. Many babies recover fully from NEC. Some babies recover but face lifelong neurological and nutritional complications. Tragically, some babies die from NEC. Surgical NEC survival rates are improving, but according to the C.D.C., NEC is still a leading cause of overall infant mortality in the United States.

Research is still needed to fully understand why NEC occurs, when NEC occurs, how NEC occurs, and which neonates will develop the disease.

Click here for a printable version of the NEC info sheet

Additional Information for Families: 

For many families, the first time they learn about necrotizing enterocolitis (NEC) is when their baby has very suddenly become ill with a distended abdomen, bloody stools, and episodes of apnea (not breathing) and bradycardia (low heart rate). The word “necrotizing” means the process of tissue death and the word “enterocolitis” means inflammation of the small intestine or colon. There is really no other disease quite like it in which large sections of the intestines become necrotic and die. NEC is common and can be fatal. It is mostly a disease of premature babies, and the most common cause of death in very premature infants after two weeks of age. NEC usually strikes very suddenly and can progress rapidly. It is a complicated disease and is best understood by categories:

  1. Classic NEC: this is the most common presentation of NEC. A premature infant (most commonly born less than 28 weeks) is 3-6 weeks old and stable, and then within hours develops signs of NEC: a hard distended abdomen that feels like a bowling ball, bloody stools, decreased activity, apnea, bradycardia, low platelet count, and an X-ray with a very characteristic appearance. Sometimes the baby has some mild symptoms like lethargy and poor feeding for a day or two beforehand, but usually there is little or no warning. Some studies have shown that days before the onset of classic NEC, the intestine becomes colonized with large numbers of a certain kind of bacteria that is known to cause inflammation.
  2. Transfusion-associated NEC: about 1/3 of all NEC cases occur in a premature infant within 2 or 3 days after a blood transfusion. It appears that the combination of severe anemia and a transfusion is particularly risky.
  3. NEC outbreaks: there are reports in the scientific literature of clusters of cases of NEC in which several premature babies in the same NICU get NEC in a short time period, sometimes with evidence of the same bacteria or virus in each baby. Some of these outbreaks have been related to contaminated infant formula or germs that are commonly found in hospitals. These outbreaks are uncommon.
  4. Atypical NEC: sometimes NEC presents in an unusual fashion. For instance, it is not typical for NEC to occur in the first week of life or before a baby has been fed.
  5. Term infant NEC: the risk of NEC in a baby born at term (37-41 weeks) is about 1 in 10,000. Most term babies with NEC have one of the following: a birth defect involving the heart, a birth defect of the intestines called gastroschisis, or an episode of low oxygen that may occur before or during a difficult birth.

What causes NEC?

The best explanation is some kind of injury to the inside lining of the intestine that then allows bacteria to travel from inside the intestine into the bloodstream. In classic NEC the injury may be inflammation caused by particularly aggressive bacteria. In transfusion-associated NEC, severe anemia may cause an injury that is worsened by the transfusion. In NEC outbreaks a specific bacteria or virus triggers the intestinal injury, and in term NEC, low oxygen levels may cause the injury.

Can NEC be prevented?

While we cannot eliminate the risks of NEC, the following appear to be helpful in decreasing the risks of NEC: 

  • Avoiding the overuse of antibiotics and acid-blocking agents
  • Feeding of breast milk
  • Administration of certain probiotics

Mother’s own milk is generally better at preventing NEC than donor human milk, but both mother’s milk and donor milk are better protection than formula. Some studies have shown that the combination of human milk and probiotics is more effective prevention than formula and probiotics.

Is there any treatment for NEC?

Standard treatment for NEC is to stop all feedings, place a large tube through the mouth into the stomach to keep the stomach empty, start antibiotics, and check x-rays of the abdomen at regular intervals. If the baby has signs that the intestine is severely injured, surgery is necessary to remove the dead portion of the intestine. In severe cases, the entire intestine may be dead and when that happens the chance of the baby surviving is very low.

You can learn more by checking out our educational resources

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