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Necrotizing Enterocolitis : Types, Causes, Stages, Diagnosis, Treatment, Complications : Anatomy

Jun 19, 2023

Necrotizing Enterocolitis : Types, Causes, Stages, Diagnosis, Treatment, Complications : Anatomy

Necrotizing enterocolitis, or NEC, is a deadly condition that usually affects premature newborns' intestines. It often occurs in infants who are fed formula milk rather than breast milk within the first two weeks of life. In this situation, the intestine's wall is invaded by bacteria. It starts to swell up. This may result in a split or opening that permits pathogenic microorganisms to enter the abdomen. It can cause serious illness and even death if left untreated. The part of the intestine most commonly involved in NEC is the Terminal ileum and ascending colon.

Read this blog further to get a quick overview of this important topic for anatomy and ace your NEET PG exam preparation.

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Types of Necrotizing enterocolitis

  • Classic: Infants born before 28 weeks of pregnancy typically have this most prevalent form of NEC. Three to six weeks after birth is when classic NEC manifests. The infant is typically stable and doing well. The condition then develops unexpectedly and without prior notice.
  • Anaemia (low of red blood cells) in infants is often treated with a blood transfusion. Within three days of receiving a blood transfusion, almost 1 in 3 premature newborns develop NEC.
  • Unusual: NEC seldom manifests in newborns during the first week of life or before the first feeding.
  • Term baby: Most full-term infants with NEC have a birth abnormality. Possible contributing factors include low oxygen levels during birth, gastroschisis (intestines that originate outside of the body), and congenital cardiac disease.

Cause of Necrotizing enterocolitis

Depending on the nature and etiology, NEC often appears two to six weeks after birth. In babies who otherwise appear to be doing well, symptoms may develop gradually over a few days or strike suddenly.

NEC is a prevalent issue for newborns in NICUs. The medical staff caring for your child will be watching for indications of this issue.

Symptoms of Necrotizing Enterocolitis

NEC symptoms include:

  • Swelling and pain in the abdomen.
  • Changes in respiration, body temperature, blood pressure, and heart rate.
  • Vomiting and bloody stools.
  • Yellow or green vomit.
  • Lethargy.
  • Absence of weight growth and refusal to eat.

Risk Factors of Necrotizing Enterocolitis

Following are explained some of the risk factors for necrotizing enterocolitis

  •  Prematurity 
  • Aggressive use of formula feeding and lack of breastfeeding
  • Fetal hypoxia
  • Maternal cocaine abuse 
  • Absent or reversed end diastolic flow in the umbilical artery on antenatal USG

Staging of Necrotizing enterocolitis

Modified Bell’s staging of NEC

Stage I (NEC suspect)

General Features

  • Temperature disturbances like fever or hypothermia
  • Apnea
  • Lethargy 

Abdominal features

  • Feed intolerance
  • Blood in stools


  • Abdominal X-ray: Normal or mild intestinal dilatation 
  • In stage IA: Occult blood positive in stool 
  • Stage IB: Fresh blood present in the stool of the baby 


  • Keep baby nil per oral
  • IV fluids 48-72 hrs 
  • IV antibiotics (for sepsis) then reassess 

Stage II (Definitive NEC)

General Features

  • Same as Stage I

Abdominal features

  • Absent bowel sounds 
  • Mild abdominal distension


  • Abdominal X-ray: 
    • Stage IIA: Pneumatosis intestinalis (Air in the wall of the intestine)
    • Stage IIB: Portal vein gas


  • Nil per oral
  • IV fluids 7-10 days
  • IV antibiotics
  • Start Total parenteral nutrition and then reassess 

Stage III (Advanced NEC)

General Features

  • Shock
  • Bleeding manifestations
  • Life-threatening apnea 

Abdominal features

  • Huge abdominal distension and tender
  • Abdominal wall cellulitis


  • Stage IIIa: Peritonitis on USG or Abdominal X-ray 
  • Stage III b: Pneumoperitoneum (due to intestinal perforation)


  • Same as Stage II
  •  IV fluids bolus (for shock)
  • Blood products (for bleeding)
  • Intubation or mechanical ventilation (Life-threatening apnea)
  • In Stage III b for intestinal perforation: Surgery 
  • Palliative procedure if the condition of the baby is not suitable for surgery 
    • Insert glove drain from which the fecal matter of the baby can be drained from the peritoneal cavity 

It is the most severe form of NEC 

  • Triad of blood investigations findings in NEC
    • Severe metabolic acidosis
    • Hyponatremia 
    • Refractory thrombocytopenia (persisting)

Complications of Necrotizing enterocolitis

  • Internal infection: The gut wall can become damaged in some newborns. Bacteria can enter the abdominal cavity thanks to this breach. Peritonitis, an infection, might develop. Sepsis, a blood infection with a high mortality rate, is made more likely by peritonitis.
  • As many as one in three infants can develop intestinal strictures. Intestine strictures make them smaller. A baby usually develops this disease a few months after he or she recovers from NEC. Food has a hard time passing through a constricted gut. For certain kids, intestinal surgery is required.
  • Short bowel (short gut) syndrome: A kid may experience short bowel (short gut) syndrome if NEC damages or destroys a portion of the small intestine. Malabsorption is a disorder that makes it difficult for the body to absorb water and nutrients. Providing the proper nutrients for growth is a lifelong responsibility for children with small bowel syndrome. Some kids require intravenous (tube) feedings.
  • Deficiencies in growth and developmental delays: Growth failure, poor neurodevelopmental results, and developmental delays are significant long-term risks, particularly in newborns who underwent surgery. To track growth and development, these infants need to be closely followed.

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