Introduction

Necrotizing enterocolitis is a serious health condition that affects the intestines of newborns, particularly those born prematurely or with low birth weight. This intestinal problem can be damaging and potentially fatal to newborns. 

Although it is difficult to understand why Necrotizing enterocolitis (NEC) happens, prematurity is a leading cause of this condition.¹

This is because the premature baby’s intestines developed poorly, leading to slow movement of intestinal contents, low stomach acid, and low digestive enzymes. Also, the walls of the intestines are easily damaged, leading to more problems that can affect the lungs and brain. 

Diagnosing NEC can be complicated. Useful signs include:^1,2

• Inability to tolerate feeding
• Bloated abdomen
• Blood in the stool
• Presence of infection, which may show as changes in
  • body temperature
  • number of breath counts per minute
  • number of heart beat per minute
  • blood pressure
• Vomiting 

In addition to the above signs, your doctor will order more tests, such as:

• C-reactive protein (CRP) and procalcitonin (PCT) levels
• Blood gas analysis and electrolyte results
• Blood, urine, stool, and spinal fluid cultures
• Imaging, such as an X-ray²

It is important to classify NEC as this helps your doctor understand the extent of the condition, decide the best treatment plan, predict treatment outcomes, and monitor the progress of treatment. Bell's staging criteria is an important tool in understanding and diagnosing NEC. 

The Bell's staging criteria takes into consideration the signs of the condition in addition to X-ray findings, and classifies NEC in three stages. 

Stage one presents with mild symptoms and is classified as a suspected stage. With worsening signs comes the confirmatory stage two. The condition progresses to stage three with notable negative health effects on other organs. Treatment of NEC differs according to the stage of the condition.¹

Bell’s staging criteria

This staging criteria is guided by the signs of NEC and abdominal X-ray findings. Kliegman and Walsh published an updated, more refined version of Bell's staging criteria in 1986. It has since become a widely adopted tool to help with the diagnosis and treatment of NEC. 

Stage I 

This stage is called suspected NEC. The signs are general signs of being unwell, not specific. It is further subdivided into stages IA and IB

IA

General (systemic) signs: 

• Unstable body temperature
• Breathing problems (apnoea) 
• Low heart rate (bradycardia) 
• Extreme tiredness ( lethargy) 

Intestinal signs:

• Vomiting
• Bloated abdomen
• Bloody stool

X-ray findings:

• Reduced bowel movement (mild ileus)³
• Normal intestines (sometimes) 
• Enlargement of the intestines

IB

Identical signs and findings are present here as in IA. Additionally, there is more bloody stool than in IA. 

Stage II

NEC is confirmed at this stage. It is further subdivided into IIA and IIB

IIA: Confirmed with mild illness

General (systemic signs):

• All the signs in stage I
  • Unstable body temperature
  • Breathing problems (apnoea) 
  • Low heart rate (bradycardia) 
  • Extreme tiredness (lethargy) 

Intestinal signs:

• Plus or minus abdominal pain
• No bowel sound

X-ray findings:

• Reduced bowel movement
• Presence of gas in the intestines
• Enlargement of the intestines

IIB: Confirmed with moderate illness

General (systemic) signs:

• Low platelet count (thrombocytopenia) 
• Blood acidosis (metabolic)
• All the signs of IIA

Intestinal signs:

• Confirmed tender abdomen
• No bowel sounds
• Plus or minus swelling on the lower right side of the abdomen 
• Abdominal skin and tissue infection (may or may not be present) 

X-ray findings:

• Presence of gas in the blood vessel carrying from the intestines to the liver
• Accumulation of fluid (ascites) in the abdominal cavity (may or may not be present) 

Stage III

At this stage, NEC has become advanced with more severe signs. It is further subdivided into IIIA and IIIB. 

IIIA: Advanced stage, the infant is severely unwell with no perforation to the intestines. 

General (systemic) signs:

• Low blood pressure
• Slow heart rate
• Low neutrophil count
• Blood acidosis (both metabolic and respiratory) 
• Severe breathing problems
• Blood clotting problems
• All the signs of stage IIB

Intestinal signs:

• Severe abdominal pain
• Severe abdominal swelling
• Presence of peritonitis
• All the signs of stage IIB

X-ray findings:

• Confirmed accumulation of fluid (ascites) in the abdominal cavity

IIIB: Advanced stage, the infant is severely unwell with perforation to the intestines. 

General (systemic) findings:

• Same findings as in IIIA

Intestinal findings:

• Same findings as in IIIA

X-ray findings:

• Presence of free air in the abdominal cavity confirmed the perforation of the intestines

Management of necrotizing enterocolitis based on staging

Stage I

• Food by mouth is withheld
• Treatment with antibiotics for up to three days or more
• A special type of feeding through the veins is initiated (parenteral nutrition) 
• Continuous monitoring and observation³

Stage II

• Treatment with antibiotics for seven to fourteen days
• No food by mouth
• Continuous monitoring and observation
• Treatment for acidosis

Stage III

• Drainage of abdominal fluid (paracentesis) 
• Treatment for acidosis
• Breathing support with a ventilator
• Treatment with intravenous fluids
• Treatment with medicines to support heart function
• Surgery, particularly stage IIIB

Table of summary of Bell's staging criteria for necrotizing Enterocolitis showing the stages and findings

This table is an original interpretation and design by Numtas, based on Bell’s Staging Criteria.

Prevention of necrotizing enterocolitis

The most important way to prevent NEC is to prevent premature birth. Where this is not possible, the following can reduce the risk of developing NEC even if the infant is born prematurely.⁴

• Breastfeeding: The breast milk of a mother contains important elements that play a vital role in defending the infant's system from illnesses. Starting to breastfeed early enough after birth can reduce the risk of developing NEC
• Short term withholding of feed: In the event of illness where the infant's feed must be withheld, care should be taken to avoid long term withdrawal. A small but frequent method of feeding can be initiated instead of complete withholding
• Use of probiotics can also reduce the risk of developing NEC²

Complications of necrotizing enterocolitis

NEC is a fatal condition that can result in a number of complications, such as²

• Perforation of the intestines
• Severe infection
• Loss of life
• Narrowing of the intestines (stricture) 
• Short bowel syndrome⁵

Summary

Necrotizing enterocolitis is a serious, life-threatening disease of the intestines. Although risk factors exist, prematurity is the single most important cause of this health problem. A widely adopted method of classifying NEC is Bell's staging criteria. It classifies the condition into three stages–suspected, confirmed, and advanced, based on clinical signs and X-ray findings. While the first two stages can be managed without surgery, surgical intervention becomes a necessity in the face of intestinal perforation in the advanced stage. Early detection can go a long way in preventing further damage to the newborn.