Necrotizing enterocolitis (NEC) is a life-threatening gastrointestinal disease that mainly affects premature infants. It involves infection and inflammation of the intestines that can lead to tissue death. The exact causes are unknown but factors like prematurity, formula-feeding, and bacterial colonization may play a role. Symptoms include abdominal distention, bloody stools, and poor feeding. Staging of NEC ranges from mild abdominal symptoms to full thickness intestinal necrosis with systemic involvement. Treatment depends on stage but may include antibiotics, surgery, and in severe cases, bowel resection.

1. Necrotizing Enterocolitis
(NEC)
MARY DAWOUD

2. Content:.
• Introduction of NEC.
• Etiology of NEC.

3. Introduction:.
• NEC is the most common life threatening emergency of the gastrointestinal
tract in the newborn.
• "Necrotizing" means the death of tissue,
"entero" refers to the small intestine,
"colo" to the large intestine,
and "itis" means inflammation.
• NEC involves infection and inflammation that causes destruction of the
bowel (intestine) or part of the bowel
• Intestinal necrosis that can involve all layers of the bowel.
• Most commonly involves the ileum and colon but can occur anywhere.

4. Epidemiology:.
• Incidence: 0.3-2.4 / 1000 live births
2-5 % of all NICU admissions
• One of the most serious GI diseases of neonates,
especially preterm infants about 90% of cases.
• Although rare, the disease does occur in term infants
(10%)
• Increased incidence with decreasing body weight and
gestation age.
 Sex, race, geography, climate has no role in determining the incidence
of NEC
 Prematurity is the single greatest risk factor

5. Risk for NEC:.
Intestinal ischemia (injury)
Enteral nutrition Pathogenic organisms

6. Risk factors influencing NEC predisposition :.
• Prematurity is the single greatest risk factor. (The mean gestational age of infants with
NEC is 30 to 32 weeks, and the infants generally are weight appropriate for gestational
age.) , Low birth weight.
• Enteral feeding of premature infants
– Hypertonic formula/enteral meds
– Breast milk protective compared to formula
– Rate of feeds and timing of initiation of feeds don’t change rates of NEC.
• Exchange transfusion.
• Umbilical artery catheterization
• Abnormal bacterial colonization:
 Prolonged empirical antibiotic therapy
 Increased pathogenic bacteria
 Maternal cocaine abuse – 2.5 times increases risk

7. Risk Factors: in Term Babies:.
Limited to those that have some underlying illness or condition requiring
NICU admission.
• Congenital Heart Disease
• Intrauterine growth restriction
• Polycythaemia
• Hypoxic-ischemic events

8. PATHOLOGY AND PATHOGENESIS: .
• Distal part of the ileum and Proximal segment of colon
are Involved most frequently.
 NEC probably results from an interaction between loss of
mucosal integrity due to factors like ischemia, infection,
inflammation, and the host's response to that injury like
circulatory, immunologic, inflammatory responses resulting
in necrosis of the affected area.
 In fatal cases, gangrene may extend from the stomach to the
rectum.

9. MUCOSAL INJURY
PRIMARY INFECTIOUS AGENTS
Bacteria, Bacterial toxin, Virus,
Fungus
CIRCULATORY INSTABILITY
Hypoxic-ischemic event
Polycythemia
INFLAMMATORY MEDIATORS
Inflammatory cells (macrophage)
Platelet activating factor (PAF)
ENTERAL FEEDINGS
Hypertonic formula or medication
Malabsorption, gaseous distention
H2 gas production, Endotoxin
production

10. Microbiologic Flora and Infection:.
Various bacterial and viral agents, but non has been
proven to be causative:
– Escherichia coli
– Coagulase-negative staphylococci: SIP
– Clostridium perfringens

11. Symptoms:.
Divided into
Systemic
Signs
Specific
Signs
Lethargy, irritability.
Poor feeding.
Temperature instability (sepsis).
Mottling ( low peripheral
perfusion), hypotension.
Respiratory distress, apnea.
Bradycardia, shock, DIC.
Weak reflux especially Moro and
suckling.
Feeding residual.
Abdominal distention.
Vomiting (bilious or bloody
vomitus).
Abdominal tenderness, ascites.
S&s of sepsis.
Firm abdomen , persistent
localized abdominal mass.
Occult blood in stool.

13.  CBC :. Leukocytosis or thrombocytopenia.
 Arterial blood gases:. Acidosis.
 Stool analysis:. for blood.
 Chemistry:. Hyponatremia and
hyperkalemia.
 The most triad of signs of advanced cases
are thrombocytopenia, persistent
metabolic acidosis and severe refractory
Hyponatremia.
Investigations
Laboratory
studies:.
Radiologic
studies:.
 Abdominal x-ray studies :.
 Abdominal gas pattern.
 Bowel wall edema.
 Fixed position loop.
 Portal or hepatic venous air.
 Pneumoperitoneum ( football sign or
air under the diaphragm or soap
bubbles).
 Abdominal ultrasound.

14. Staging criteria for NEC:.
stage I:.
 Systemic signs:.
• Temperature instability.
• Apnea, bradycardia.
• Lethargy.
 Intestinal signs:.
• Mild abdominal distention.
• Elevated pre-gavage residuals.
• Emesis.
• Bright red blood from rectum.
 Radiological signs:.
• Normal or nonspecific (intestinal dilatation, mild ileus)

15. Staging criteria for NEC cont.
Stage II:.
 Systemic signs:.
• Temperature instability.
• Apnea, bradycardia.
• Lethargy.
• Mild acidosis.
• Thrombocytopenia.
 Intestinal signs:.
• Mild abdominal distention and abdominal tenderness.
• Elevated pre-gavage residuals.
• Emesis.
• Absent bowel sounds.
• Right lower quadrant mass.
 Radiological signs:.
• Intestinal dilatation, ileus and pneumatosis intestinalis.
• Portal venous gas.
• May be ascites.

16. Staging criteria for NEC cont.
 Stage III:.
 Systemic signs:.
• Temperature instability.
• Severe apnea, bradycardia.
• Lethargy, hypotension, oliguria.
• Thrombocytopenia, DIC.
• Respiratory and metabolic acidosis
 Intestinal signs:.
• Mild abdominal distention and marked abdominal tenderness.
• Elevated pre-gavage residuals.
• Emesis, Absent bowel sounds.
• Discoloration of abdominal wall.
• Right lower quadrant mass.
• Signs of generalized peritonitis
 Radiological signs:.
• Intestinal dilatation, ileus and pneumatosis intestinalis.
• Portal venous gas.
• Ascites.
• Pneumoperitoneum.