Necrotizing enterocolitis (NEC) is a life threatening gastrointestinal disorder that can cause bowel inflammation in newborns. To help diagnose and classify NEC, doctors may use a variety of staging methods, such as the Bell staging method.

In necrotizing enterocolitis (NEC), bacteria invade a section of the gastrointestinal tract causing cellular damage and eventual death of the colon and intestine. NEC is common among premature infants during the second or third week of life. It is a major cause of gastrointestinal admissions in the neonatal intensive care unit (NICU).

Evidence indicates that the incidence of NEC can vary from 3–24 infants per 10,000 live births, with most cases occurring in premature infants. NEC staging systems can have important implications, as they can help doctors provide the most suitable and effective treatment.

This article explores the different staging methods for necrotizing enterocolitis, including symptoms and treatment options.

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Dr. Martin Bell and colleagues proposed the first NEC classification system in 1978. The Bell staging system included a set of characteristics used to classify infants into 1 of 3 stages of NEC.

Stage 1

This is the stage of suspected NEC where symptoms indicate early onset gastrointestinal disease. These may include:

  • lethargy
  • vomiting
  • bloody stools
  • mild abdominal bloating
  • slow heart rate
  • unstable temperature

Stage 2

Stage 2 is the stage of confirmed NEC. Symptoms include all the stage 1 indicators and the following:

  • lack of bowel sounds
  • pain or tenderness in the abdomen
  • low or no intestinal movement
  • presence of gas-filled spaces in the intestinal walls

Stage 3

Stage 3, or advanced NEC, encompasses all stage 1 and stage 2 indicators, as well as:

  • low blood pressure
  • low white blood cell count
  • blood clot formation
  • inflammation of abdominal tissues
  • buildup of fluid and gases in the abdominal cavity

Other NEC staging methods include the following:

Vermont Oxford Network (VON) definition

The VON criteria define NEC as a diagnosis at surgery, post-mortem examination, or based on clinical and radiographic criteria. According to VON criteria, infants must have a clinical sign in addition to one radiographic symptom.

Examples of clinical symptoms include:

  • emesis
  • abdominal distension
  • blood in stool

In addition, the following are the radiographic findings of the VON criteria:

  • hepato-biliary gas
  • pneumatosis intestinalis
  • pneumoperitoneum

Centers for Disease Control and Prevention (CDC)

While the CDC shares similar clinical and imaging symptoms with the VON definition, it has some slight modifications.

It also includes a surgical NEC criterion which requires an infant to have surgical evidence of either extensive bowel necrosis or pneumatosis intestinalis (gas within the wall of the small or large intestine), with or without perforation.

UK Neonatal Collaborative (UKNC-NEC)

This is a point-based, gestational, age-specific NEC classification system.

The NEC score range from 1–9. It assigns 1 point for each symptom, which includes abdominal discoloration, tenderness, increased or bilious aspirations, and abdominal distention.

This is in addition to one or more radiographic signs. It also assigns 2 points for blood in the stool and 3 points for pneumatosis intestinalis.

Two of three rule

The doctor will diagnose NEC in a preterm infant if they have two of the following symptoms:

  • pneumatosis or portal air by ultrasound or abdominal X-ray
  • persistent platelet consumption
  • postmenstrual age at disease onset more closely related to NEC than SIP

In addition to two of the above symptoms, they will also have one or more of the following:

  • abdominal distention
  • ileus
  • bloody stools

Stanford NEC score

The Stanford NEC score considers the following factors to generate a score. This includes:

  • baseline characteristics, which include postnatal age, gender, and ethnicity
  • clinical factors, such as feeding intolerance
  • clinical exam findings, which include discoloration of the abdominal wall
  • laboratory test results, such as platelet count and PH value
  • radiographic findings, such as portal venous gas or pneumatosis intestinalis

International Neonatal Consortium (INC)

This requires that infants satisfy 1 of 2 clinical signs between the 10th postnatal day and 36 weeks postmenstrual age and at least one of the following signs:

  • intestinal necrosis at laparotomy
  • pneumatosis intestinalis or portal venous air
  • evidence of vasculitis
  • coagulopathy or inflammation in the absence of a bacterial, fungal, or viral infection

According to the National Institute of Child Health and Human Development (NICHD), symptoms of NEC in a newborn include:

  • diarrhea
  • bloody stool
  • pain in the abdomen
  • swollen abdomen
  • inability to digest food

In an older baby or child, a doctor would usually suspect a different diagnosis.

Evidence indicates that NEC can progress rapidly, and symptoms can move from early onset to advanced disease and death within 24–48 hours.

Due to its fast progression, medical professionals recommend early diagnosis at the first stage. If a parent or caregiver notices symptoms of NEC in an infant, they should contact the doctor immediately. NEC often occurs when a baby is still in the NICU.

NEC treatment options depend on the stage. The doctor will evaluate a person’s symptoms and disease progression before recommending a treatment option. This includes:

  • stopping all tube feeding
  • nasogastric intubation to decompress dilated bowels
  • intravenous antibiotics, such as ampicillin, gentamicin, or metronidazole
  • total parenteral or intravenous nutrition while the infant receives no food by mouth
  • laparotomy, which is the surgical removal of the damaged sections of the intestine
  • peritoneal drainage if the infant cannot tolerate surgery

Necrotizing enterocolitis (NEC) is a life threatening condition that occurs due to inflammation in the intestine.

To guide appropriate treatment, medical experts have developed different staging methods to help clinicians accurately diagnose NEC. This includes the CDC, VON, UKNC, two of three rule, and Stanford definitions.

Without treatment, NEC can progress rapidly, causing gastrointestinal perforation and death.