Necrotizing enterocolitis (NEC)

How does this happen?

The exact cause is not settled, and current understanding describes several factors coming together rather than a single trigger. ¹

An immature bowel. A very preterm baby's bowel has a less developed barrier and a less mature immune response, so bacteria can cross the lining and provoke inflammation.

Bacterial colonization. A NICU baby's gut is colonized differently from a term baby's, and antibiotics change it further.

Blood flow. Reduced blood flow to the bowel makes tissue vulnerable.

Feeding. Feeds are the substrate for bacteria in the gut, which is why feeding practice is central to prevention even though feeding itself is essential.

Once inflammation starts, the bowel wall becomes damaged. Gas produced by bacteria tracks into the wall, which is the characteristic X-ray finding. In severe disease the wall dies and perforates, spilling contents into the abdomen. ¹

Human milk contains factors that support the gut barrier and the developing immune response, which is the basis for the association between human milk feeding and lower rates of NEC. ¹

What causes it?

Two different questions get mixed together here. The first is what leads to this injury in the body. The second is whether anyone could have prevented it. They are not the same question, and the answer to the first does not settle the second.

Happens even with perfect care

• Very preterm birth, which is the dominant risk factor and often unavoidable. ²
• Very low birth weight. ¹
• Growth restriction with poor blood flow to the bowel before birth.
• sepsis and other serious illness.
• Heart conditions affecting blood flow.
• NEC in a baby receiving optimal care, which occurs and is the most common situation.

Associated with gaps in care

These are situations where published standards say what the care team should watch for and do. A gap here does not prove anyone caused your child's injury. It points to where the medical records will have an answer.

• Antenatal corticosteroids not given when preterm birth was expected, which affects overall preterm outcomes. ^{3 4}
• Human milk not prioritized, including lactation support not offered or donor milk not used where available, when human milk feeding is associated with lower NEC rates. ¹
• Early signs not acted on, such as increasing feeding intolerance, a distended belly or bloody stool in a very preterm baby.
• Abdominal X-ray not obtained when NEC was suspected.
• Feeds not stopped once NEC was suspected.
• Surgical review not obtained where the condition was advancing.
• A baby not cared for at a hospital with the required level of newborn care, where levels and surgical availability are formally defined. ⁵

Whether any of this amounts to a departure from the standard of care takes a physician expert reading the whole record. NEC occurs in well-run units delivering excellent care.

What are the signs, by age?

Signs change as a child grows. A newborn cannot show you a walking problem. Some children look fine at first and show differences months later.

At birth and the first hours

NEC does not occur at birth. It typically develops in the days to weeks after birth in a baby who has been in the NICU.

The first week

• Feeds not being tolerated, with milk left in the stomach before the next feed.
• A belly that looks fuller, tighter or shinier, or that has visible loops.
• Vomiting, sometimes green.
• Blood in the stool.
• A baby who is more sleepy, less responsive, or having more apnea.
• Temperature instability and low blood pressure in advancing disease.

Around 3 months

• Recovery in most babies who did not need surgery.
• Feeding difficulty and slow growth after significant NEC.
• A stoma, if bowel surgery was needed, with a plan for putting the bowel back together later.
• Narrowing of the bowel, called a stricture, which can develop weeks after NEC and cause blockage.

Around 6 months

• Growth and nutrition are the main issues.
• Short bowel syndrome in babies who lost a lot of bowel, which may mean long-term intravenous nutrition.
• Developmental follow-up, since NEC requiring surgery is associated with poorer neurodevelopmental outcomes. ⁶

Around 12 months

• Feeding and growth remain the focus for many.
• Developmental delay in some children. ⁷

Toddler years

• Most children who recovered without extensive bowel loss eat normally and grow.
• Feeding aversion is common after long periods without oral feeding and responds to feeding therapy.

School age

• Learning and attention differences relating to preterm birth and to severe illness.
• Nutritional issues in children with short bowel syndrome.

How is it diagnosed?

Abdominal X-ray is the key test. The characteristic finding is gas within the wall of the bowel, called pneumatosis intestinalis. Free air outside the bowel means perforation and is a surgical emergency. ¹

Serial X-rays, because the picture changes quickly and a single film early can be normal.

Blood tests, including blood count, platelet count, inflammatory markers and blood gases. A falling platelet count and worsening acidosis are warning signs.

Blood cultures, because sepsis accompanies NEC frequently. ⁸

Abdominal ultrasound, used increasingly in some centers to assess bowel wall thickness, blood flow and free fluid.

Staging. The modified Bell system describes suspected, definite and advanced disease, and it is the language the team will use. Ask which stage your baby is at and what would change it. ¹

What is the treatment?

Medical treatment

• Stop feeds. The bowel is rested and the stomach is drained through a tube.
• Intravenous nutrition, because the baby cannot be fed by mouth for a period, usually one to two weeks.
• Antibiotics. ⁸
• Support for blood pressure, breathing and clotting.
• Serial X-rays to watch for perforation.

Most babies with early or moderate NEC recover with medical treatment. ¹

Surgery

Needed where the bowel perforates or where the baby deteriorates despite medical treatment. Options include placing a drain in the abdomen, or an operation to remove dead bowel, usually with a stoma so the bowel can rest. ¹

Afterward

• Reintroducing feeds slowly, with human milk preferred. ¹
• Watching for stricture, a narrowing that can develop weeks later and cause blockage.
• Stoma reversal, usually some months later.
• Nutrition support where a lot of bowel was lost.
• Developmental follow-up, because NEC requiring surgery is associated with poorer neurodevelopmental outcomes. ⁶ Referral to early intervention is free to evaluate. ⁹

What is the long-term outlook?

Most babies with medically treated NEC recover and feed normally. ¹

Babies who need surgery have a harder course, with substantial mortality and a higher rate of long-term problems including short bowel syndrome and developmental difficulties. ¹

Complications to watch for after recovery are bowel strictures, feeding aversion after a long period without oral feeding, and growth problems.

Developmental outcomes in babies who needed surgery for NEC are less good than in preterm babies who did not, which is why follow-up matters even when the bowel has healed. ⁶

What does daily life look like?

In the NICU: feeds stopped, a drain in the stomach, intravenous nutrition, and daily X-rays. Families describe the waiting as the hardest part.

If there is a stoma, learning stoma care, which is taught before discharge.

At home: often feeding is the central issue for months. Feeding therapy helps and is worth asking for early rather than waiting for a problem to entrench.

If you are expressing milk, that is a direct contribution to your baby's treatment in this condition, and it is worth saying to parents who feel there is nothing they can do. ¹

What does care cost over a lifetime?

NEC requiring surgery is among the most expensive newborn conditions in terms of hospital care, driven by long intensive care stays and repeated procedures. National data on children's hospital stays is collected in the Kids' Inpatient Database. ¹⁰

No agency publishes a current per-child lifetime cost estimate for NEC, and this site does not invent one.

Where short bowel syndrome results, long-term nutrition costs are significant. See paying for care and Medicaid home and community based services. ¹¹

What can you do this week?

1. Ask what stage of NEC your baby has and what would change it.
2. Ask what the X-rays show and how often they are being repeated.
3. Ask whether surgery is being considered and what would trigger it.
4. Ask about human milk, including donor milk if your own supply is not established. ¹
5. Ask when feeds will restart and how they will be advanced.
6. Ask about stricture, and what signs to report after recovery.
7. Ask for developmental follow-up to be arranged before discharge.

What should you ask each specialist?

Take these with you. Write the answers down in the moment, because you will not remember them later.

For the neonatologist

• What stage is this, and is it advancing?
• What do the X-rays show, and how often are they repeated?
• What would make you call the surgeons?
• How long will feeds be stopped?
• Can my baby have human milk, including donor milk?

For the surgeon

• How much bowel is affected, and how much would be removed?
• Will there be a stoma, and when would it be reversed?
• What is the risk of short bowel syndrome?
• What should we watch for after recovery?

For the feeding team

• How will feeds be restarted and advanced?
• What are the signs of a stricture?
• How do we prevent feeding aversion after this long without oral feeding?

You can also build a printable list with the question generator.