What is NEC?
Learn about necrotizing enterocolitis, a devastating intestinal disease that primarily affects premature and medically fragile infants.
Teddy
Understanding Necrotizing Enterocolitis
Necrotizing enterocolitis (NEC) is a devastating intestinal disease that primarily affects premature infants. NEC can also affect term babies, especially infants with a medical condition, like a congenital heart defect. NEC causes severe inflammation of the intestine, leading to a bacterial infection causing necrosis (tissue death).
NEC is a leading cause of death in neonatal intensive care units (NICUs) and is the most common and deadly gastrointestinal disease affecting premature and medically fragile infants. Many babies recover fully from NEC. Some babies recover but face lifelong neurological and nutritional complications. Tragically, some babies die from NEC.
Research is needed to fully understand why NEC occurs, when NEC occurs, how NEC occurs, and which neonates will develop the disease.
What causes NEC?
NEC is multifactorial and there is no single cause. More research is needed to fully understand why some babies develop NEC.
Factors that increase the risk for NEC include premature birth, low birth weight, absence of mother’s (or donor) milk, and severe anemia.
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.
Are there different categories of NEC?
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:
- 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.
- 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.
- 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.
- 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.
- 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 are the long-term outcomes of NEC?
Infants that survive NEC often struggle with life-long complications such as short-bowel syndrome.
We partnered in a research study led by Jennifer Canvasser, the Executive Director of the NEC Society, and James Harrison from the University of California San Francisco.
Learn More about NEC
Human Milk and NEC
Explore human milk's role in protecting against NEC in our webinar series.
Long-Term Outcomes of NEC
We surveyed the long-term outcomes of NEC on survivors and families.
Helpful Articles
This collection of articles is designed to support families, caregivers, and healthcare professionals in understanding necrotizing enterocolitis (NEC).
