nec necrotising enterocolitis in preterm.pptx

Necrotizing Enterocolitis (NEC)


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Definition

Necrotizing enterocolitis (NEC) is a serious inflammatory disease of the intestine that primarily affects premature neonates, leading to intestinal necrosis and sometimes perforation.


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Epidemiology

Most common gastrointestinal emergency in ne...

Necrotizing Enterocolitis (NEC)


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Definition

Necrotizing enterocolitis (NEC) is a serious inflammatory disease of the intestine that primarily affects premature neonates, leading to intestinal necrosis and sometimes perforation.


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Epidemiology

Most common gastrointestinal emergency in neonates.

Occurs in 1–5% of NICU admissions.

90% of cases occur in preterm infants (< 37 weeks).

Incidence increases with lower gestational age and birth weight (< 1500 g).



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Etiology and Risk Factors

1. Prematurity → immature gut barrier and immune defense.


2. Enteral feeding (especially formula) → bacterial overgrowth and ischemia.


3. Intestinal ischemia → hypoxia, hypotension, PDA, sepsis.


4. Bacterial colonization → pathogens like Klebsiella, E. coli, Clostridium perfringens.


5. Other factors:

Rapid feeding advancement

Indomethacin therapy

Polycythemia

Congenital heart disease





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Pathophysiology

Initial insult → intestinal mucosal injury (due to hypoxia or feeding).

Bacterial invasion → gas formation in the bowel wall (pneumatosis intestinalis).

Inflammation and necrosis → may progress to perforation and peritonitis.



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Clinical Features

Usually appear between day 5–14 of life.

Systemic Signs

Lethargy, apnea, temperature instability

Feeding intolerance, increased gastric residuals

Abdominal distension, tenderness

Signs of sepsis or shock


Gastrointestinal Signs

Bloody stools

Abdominal discoloration (bluish)

Visible bowel loops

Abdominal wall erythema (late sign)



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Investigations

Laboratory Findings

CBC: leukopenia or leukocytosis, thrombocytopenia

Metabolic acidosis

Elevated CRP

Blood cultures: often positive


Imaging (Key diagnostic tool)

Abdominal X-ray:

Pneumatosis intestinalis → gas in bowel wall (pathognomonic)

Portal venous gas

Free air under diaphragm → perforation


Abdominal ultrasound:

Useful for early detection and perfusion assessment.




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Staging (Modified Bell’s Classification)

Stage Features Findings

I (Suspected) Nonspecific signs Mild distension, occult blood, normal X-ray
II (Definite) Classic NEC Pneumatosis intestinalis, portal venous gas
III (Advanced) Severe NEC Perforation, peritonitis, shock



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Management

Initial (Medical) Management

Bowel rest: Stop enteral feeds (NPO)

Gastric decompression: Replogle tube

IV fluids and TPN

Broad-spectrum IV antibiotics:

e.g. Ampicillin + Gentamicin + Metronidazole (or Cefotaxime + Metronidazole)


Monitor: electrolytes, acid-base status, urine output

Serial abdominal X-rays


Surgical Indications

Perforation (free air on X-ray)

Failure of medical therapy

Abdominal wall erythema, fixed mass, or severe sepsis


Surgical Options

Peritoneal drainage (for unstable or very low birth weight infants)

Laparotomy with resection of necrotic bowel ± stoma creation



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Complications

Short bowel syndrome (after extensive resection)

Intestinal stricture (esp. colonic)

Sepsis and multiorgan failure

Neurodevelopme