Introduction

Necrotising enterocolitis (NEC) is a serious and life-threatening disorder that almost exclusively affects premature newborns. It usually develops within two to four weeks following birth and involves intestinal inflammation, which leads to bacterial invasion, cell damage, and cell death of the intestine and colon. As NEC advances, intestinal perforation can happen, and bacteria may leak into the belly and blood, causing peritonitis, sepsis, and death.^1,2 

The exact cause of NEC is unknown, and the mechanism of the disease progression is poorly understood. However, the immaturity of the gastrointestinal tracts and the weakened immune systems in premature babies are thought to play a part in the development. Normally, the mortality rate of NEC is between 10%-50%, but in severe cases, it increases to 100%. For those who survive, 9-36% experience long-term digestive system sequela like intestinal stenosis.^1,2,3

Signs and symptoms 

The manifestations may appear a couple of days after birth or suddenly in newborns who are doing well. These include:^1,2

• Abdominal pain/tenderness and swelling
• Decreased appetite and poor eating
• Deceased activity and fatigue
• Increased abdominal girth
• Vomiting (including green or yellow vomit)
• Lethargy
• Lack of weight gain
• Changes in heart rate, blood pressure, body temperature and breathing
• Diarrhoea with bloody stool

The findings of a physical examination can include visible intestinal loops, decreased bowel sounds, noticeable abdominal mass, and erythema of the abdominal wall. Additionally, systemic findings may show respiratory failure, circulatory collapse, and decreased blood flow in the extremities.²

Risk factors

• Prematurity
• Low birth weight
• Formula feeding
• Tube feeding (enteral nutrition)
• Genetics

Types of NEC

The form of necrotising enterocolitis (NEC) depends on when symptoms begin as well as the initial cause. The different types include:¹

Classic

This is the most common type of NEC, which usually impacts infants born before 28 weeks of pregnancy and happens three to six weeks after birth. Often, the newborn is stable, and the condition comes on abruptly.¹

Transfusion-associated

In premature babies who receive a blood transfusion to treat anaemia, it is possible to develop NEC. It affects 1 in 3 of these neonates and typically within three days of receiving the blood transfusion.¹

Atypical

Infrequently, an infant may develop NEC in the first week following birth or before their first feeding.¹

Term infant

Importantly, full-term babies who get NEC normally have a birth defect such as a congenital heart condition, gastroschisis, or birth asphyxia. NEC outbreaks, while rare, can happen in neonatal intensive care units (NICUs) where numerous infants can develop NEC at the same time. Bacteria or other germs can be the cause of these outbreaks.¹

Neurodevelopmental impairment (NDI)

Neonates with necrotising enterocolitis (NEC) are at risk of developing neurodevelopmental impairment (NDI), with its incidence being approximately 40% compared to the 20% observed in infants without NEC. Previous studies have shown that these babies are at an increased risk of periventricular leukomalacia (PVL), intracranial haemorrhage (IVH), cerebral palsy (CP), as well as visual and hearing impairment. Evidence has also suggested a higher risk of behavioural issues, such as attention deficits, in children who survived NEC.³

It is important to note that certain factors, namely gestational age, infection, and birth weight, are already related to brain injury. Also, the surgical management of NEC is another factor which increases the chance of NDI development versus conservative, medical treatment.³

Growth impairment

Growth defect is another recognised complication of necrotising enterocolitis (NEC). Studies showed that compared to babies without NEC, those affected were shorter in size at 18 months of age. As with neurodevelopmental impairment (NDI), neonates who undergo surgical intervention for NEC have lower weights, head circumferences and lengths, compared to neonates treated with medicines and those without NEC.^2,4,5

Researchers have reported that at age 15, children who had NEC needing surgery were shorter, weighed less and had lower BMI compared to children who never had NEC.⁶

Follow-up and management strategies

Multidisciplinary care

Babies diagnosed with NEC require attentiveness from a neonatal intensivist and most likely a surgical consult, as well as paediatrics and nutrition.²

Nutritional support

One of the first steps in managing NEC is to cease tube or oral feeding and instead provide fluids and nutrients intravenously.^1,2 

Medical interventions

A nasogastric tube is placed to decompress dilated bowels, ridding the stomach of gas and fluids. Intravenous, broad-spectrum antibiotics are prescribed to fight against bacterial infections, with the proposed regimen being ampicillin, gentamicin and either clindamycin or metronidazole.^1,2 

Surgery

A laparotomy is the standard surgical method done in infants with NEC, where portions of definite necrotic or perforated intestine are removed to try to preserve as much intestine as possible. This approach can be contraindicated in patients who are severely ill, as they may be too frail to endure the surgery. In these cases, if intestinal perforation and free air are present, insertion of a peritoneal drain may be done.² 

Future treatments

Currently, other options like probiotics are being studied.² 

FAQs

Q. What are the long-term complications of necrotising enterocolitis?

Long-term complications of NEC can include problems with growth, digestion, and brain development. Many children may have difficulty gaining weight or growing properly, especially if they had surgery to remove damaged parts of the intestine. They may also experience feeding problems or need long-term nutritional support. Some children develop developmental delays or learning difficulties as they grow older.^1,2,3

Q. Can NEC cause developmental delay?

NEC can lead to developmental delays, especially in babies born very early or those who had severe or surgical NEC. The illness can affect the brain indirectly through inflammation, poor nutrition, or serious infections during a critical time of brain development. These delays can affect movement, learning, speech, or behaviour.^1,3,4,5

Q. Does NEC cause brain damage?

NEC does not directly damage the brain, but the severe inflammation and infections it causes can lead to brain injury, especially in preterm infants. Low oxygen levels, poor blood flow, and stress on the body during NEC can harm the developing brain, increasing the risk of problems like cerebral palsy or learning disabilities later in life.^3,4,5

Summary

Necrotising enterocolitis (NEC) is a serious and often life-threatening condition that mainly affects premature newborns. It typically appears within the first few weeks of life and involves inflammation and damage to the intestines. In severe cases, NEC can lead to intestinal perforation, widespread infection, and even death. Although its exact cause is unknown, the condition is strongly associated with prematurity, low birth weight, formula feeding, and weakened immune function. NEC can present suddenly, with symptoms such as abdominal swelling, vomiting, and poor feeding, and it can progress rapidly.

There are several types of NEC depending on when it appears and potential triggers, including classic NEC, transfusion-associated, atypical, and NEC in full-term infants. Survivors of NEC, especially those who required surgery, are at risk for long-term complications. One major concern is neurodevelopmental impairment (NDI), which includes issues like cerebral palsy, vision and hearing problems, learning difficulties, and attention deficits. These impairments are more common in NEC survivors than in preterm infants without NEC.

Another lasting complication is growth impairment. Infants who have had NEC, particularly those who underwent surgery, often show slower growth in weight, height, and head size during infancy and even into adolescence. These outcomes are linked to the disease itself and the impact of surgical treatment on nutrient absorption and overall health.

Management of NEC involves stopping oral feeding, using intravenous nutrition, administering antibiotics, and, in severe cases, performing surgery to remove damaged portions of the intestine. Long-term care often requires a multidisciplinary team, including neonatologists, surgeons, nutritionists, and developmental specialists. New therapies, like the use of probiotics, are being explored to prevent NEC or reduce its severity in high-risk infants.