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Necrotizing Enterocolitis

Medically reviewed by: Daniel R. Dirnberger, MD

What Is Necrotizing Enterocolitis?

Necrotizing enterocolitis (nek-roh-TIE-zing en-ter-oh-coh-LIE-tis), or NEC, is the most common and serious intestinal disease among premature babies. It happens when tissue in the small or large intestine is injured or inflamed. This can lead to death of intestinal tissue and, in some cases, a hole (perforation) in the intestinal wall.

In NEC, the intestine can no longer hold waste. So may pass into the bloodstream and cause a life-threatening infection. Waste may pass into the baby's abdomen and make the baby very sick. The injured intestine, or sections of it, may die and need to be removed.

What Are the Signs & Symptoms of Necrotizing Enterocolitis?

A baby with necrotizing enterocolitis might have these symptoms:

  • a swollen or tender belly
  • red, blue, or gray discoloration of the belly
  • trouble feeding
  • food staying in the stomach longer than expected
  • constipation
  • diarrhea and/or dark or bloody stools (poop)
  • being lethargic or less active
  • a low or unstable body temperature
  • green vomit (containing bile)
  • apnea (pauses in breathing)
  • bradycardia (slowed heart rate)
  • hypotension (low blood pressure)

Symptoms of NEC can vary from baby to baby, and can be like those caused by other digestive problems.

What Causes Necrotizing Enterocolitis?

There is no single consistent cause of necrotizing enterocolitis. In most cases, a specific cause isn't found. But experts believe these things might play a role:

  • an underdeveloped (premature) intestine
  • too little oxygen or blood flow to the intestine at birth or later
  • injury to the intestinal lining
  • heavy growth of bacteria in the intestine that erodes the intestinal wall
  • viral or bacterial infection of the intestine
  • formula feeding (babies who get breast milk have a lower risk of NEC)

NEC sometimes seems to happen in "clusters," affecting several infants in the same nursery. This might be coincidental, but some viruses and bacteria occasionally have been found in babies with NEC. NEC does not spread from one baby to another, but a virus or bacteria that cause it can. This is one reason all nurseries and NICUs have very strict precautions to help prevent the spread of infections.

Most cases of necrotizing enterocolitis are in babies born before 32 weeks gestation. But full-term babies who have health problems, like a heart defect, also can have it. Babies with NEC usually develop it within the first 2–4 weeks of life.

How Is Necrotizing Enterocolitis Diagnosed?

In babies with symptoms of NEC, a diagnosis can be confirmed if an abnormal gas pattern shows up on an X-ray. This looks like a bubbly or streaky appearance of gas in the walls of the intestine.

In severe cases, air escapes from the intestine and shows up in the large veins of the liver or the abdominal cavity. A doctor may insert a needle into the belly to withdraw fluid to see whether there is a hole in the intestine.

How Is Necrotizing Enterocolitis Treated?

When NEC is diagnosed or suspected, treatment begins right away. It includes:

  • temporarily stopping all feedings
  • nasogastric or orogastric drainage (inserting a tube through the nose or mouth into the stomach to remove air and fluid from the stomach)
  • IV (given into a vein) fluids for fluid replacement and nutrition
  • antibiotics to treat a possible or confirmed infection
  • frequent exams and abdominal X-rays
  • a consultation with a pediatric surgeon to discuss surgery, if needed
  • in severe cases, surgery may be needed right away

The baby's poop is watched for blood and the baby's belly size is checked regularly. A hole in the intestine or an infection in the abdominal cavity will make the belly swell. If a baby's belly is so swollen that it affects breathing, extra oxygen or a breathing machine (ventilator) will help the baby breathe. Also, blood tests will look for bacteria and check for anemia (a decrease in red blood cells), thrombocytopenia (low platelet count), and other things. 

After responding to treatment, a baby can be back on regular feedings after a week or two. When feedings start again, breast milk is recommended. Breast milk is beneficial for babies with NEC because it is easily digested, supports the growth of healthy bacteria in the intestinal tract, and boosts a baby's immunity — which is especially important for a preterm baby with an immature immune system.

For mothers who can't breastfeed or provide enough breast milk, doctors may recommend giving the baby pasteurized human breast milk from a milk bank, which is considered a safe alternative. Special formula may also be used. These formulas provide nutrition for premature babies, and are safe and effective.

Some babies will need surgery if their condition gets worse despite medical care. The surgeon will look for a hole in the intestine and remove any dead or dying intestinal tissue. In some cases after this removal, the healthy intestine can be sewn back together. Other times, especially if the baby is very ill or a large section of the intestine was removed, an ostomy is done.

To make an ostomy, surgeons bring an area of the intestine to an opening on the abdomen (stoma) so that stool can safely exit the body. A second surgery may be done in 1–3 days to re-examine the intestines. If an ostomy is made, it will be closed 6–8 weeks later, after the intestine is fully healed and healthy again, and any inflammation in the belly has cleared up.

What Can I Expect?

Most babies who develop NEC recover fully and do not have further feeding problems. In some cases, the intestine may be scarred, narrowed, or blocked. If so, more surgery might be needed.

Malabsorption (when the intestine can't absorb nutrients normally) can be a lasting problem from NEC. It's more common in babies who had part of their intestine removed. A baby with malabsorption may need nutrition delivered directly into a vein until the intestine heals well enough to tolerate feeding.

If your baby has NEC, it's normal to worry. And not being able to feed your baby can be frustrating — infants are so small, it just doesn't feel right to stop feedings or take away that precious bonding time. But that might be the best thing for your baby during treatment. And remember, there's a good chance that your baby will be back on regular feedings soon.

In the meantime, ask a member of your care team what you can do to care for and bond with your baby. There are ways you can help. Members of your care team are eager to support you and your baby on the path to recovery.

Medically reviewed by: Daniel R. Dirnberger, MD
Date reviewed: May 2023