Necrotizing Enterocolitis

Question 1

Define Necrotizing Enterocolitis (NEC).

Answer 1

NEC is an acute, inflammatory necrosis of the intestine, primarily affecting premature neonates, leading to varying degrees of intestinal wall injury, perforation, and peritonitis.

Question 2

Describe the epidemiology of NEC.

Answer 2

Occurs mainly in preterm infants (<32 weeks, <1500g). Incidence: 1–5% of NICU admissions. Mortality 20–30%. Rare in term infants unless comorbidities (CHD, sepsis).

Question 3

List the major risk factors for NEC.

Answer 3

Prematurity, formula feeding, hypoxia/ischemia, patent ductus arteriosus, sepsis, rapid feed advancement, polycythemia, congenital heart disease.

Question 4

Explain the pathophysiology of NEC.

Answer 4

1. Immature intestinal mucosa + hypoxia → mucosal injury.
2. Bacterial invasion → gas production (pneumatosis intestinalis).
3. Inflammation → necrosis → perforation → peritonitis.
   Cycle perpetuates via cytokine release (TNF-α, IL-6).

Question 5

List early clinical features of NEC.

Answer 5

Feeding intolerance, abdominal distension, vomiting (bilious), gastric residuals, lethargy, temperature instability, apnea, bradycardia.

Question 6

List late/severe features of NEC.

Answer 6

Abdominal discoloration, tenderness, abdominal wall erythema, absent bowel sounds, bloody stools, shock, and signs of perforation (pneumoperitoneum).

Question 7

Outline key laboratory findings in NEC.

Answer 7

• CBC: neutropenia or leukocytosis, thrombocytopenia
• Metabolic acidosis
• Hyponatremia, elevated CRP
• Blood cultures: positive for Gram-negative or anaerobic organisms.

Question 8

What are the classical radiological findings in NEC?

Answer 8

1. Pneumatosis intestinalis (air within bowel wall) — pathognomonic.
2. Portal venous gas.
3. Pneumoperitoneum (if perforation).
4. Fixed bowel loops and bowel wall thickening.

Question 9

List differential diagnoses of NEC.

Answer 9

• Sepsis with ileus
• Intestinal obstruction (malrotation, atresia)
• Hirschsprung enterocolitis
• Spontaneous intestinal perforation.

Question 10

Outline general principles of NEC management.

Answer 10

1. Stop enteral feeds (NPO)
2. Nasogastric decompression
3. Broad-spectrum IV antibiotics
4. Fluid/electrolyte support
5. Parenteral nutrition
6. Serial abdominal exams & X-rays
7. Surgical consult if perforation suspected.

Question 11

List recommended antibiotics for NEC (empiric therapy).

Answer 11

Ampicillin + Gentamicin + Metronidazole (or Clindamycin). Covers Gram+/- and anaerobes. Duration: 10–14 days for medical NEC.

Question 12

State indications for surgical intervention in NEC.

Answer 12

• Pneumoperitoneum (free air)
• Fixed dilated bowel loop on serial films
• Abdominal wall erythema or tenderness
• Worsening acidosis or shock despite maximal medical therapy.

Question 13

List possible surgical procedures used in NEC.

Answer 13

1. Peritoneal drainage (for unstable preterms)
2. Laparotomy with resection of necrotic bowel
3. Stoma formation (e.g., ileostomy) ± reanastomosis later.

Question 14

List complications of NEC.

Answer 14

Short-term: perforation, sepsis, DIC, shock.
Long-term: short bowel syndrome, intestinal strictures (esp. colon), growth failure, neurodevelopmental delay.

Question 15

Describe preventive strategies for NEC.

Answer 15

1. Breastfeeding (protective factors)
2. Avoid rapid feed advancement
3. Use of probiotics (controversial)
4. Minimal enteral feeding in preterms
5. Careful oxygenation and perfusion during resuscitation.

Question 16

Summarize the Modified Bell’s Staging for NEC.

Answer 16

Stage | Clinical Features | Radiological Findings | Management
— | — | — | —
IA/IB (Suspected) | Mild distension, gastric residuals, ± bloody stool | Normal or mild ileus | NPO, observe, antibiotics 48h
IIA/IIB (Definite) | Abdominal tenderness, distension, metabolic acidosis | Pneumatosis intestinalis ± portal venous gas | NPO, IV antibiotics 7–10d, fluids, monitor
IIIA/IIIB (Advanced) | Shock, peritonitis, discoloration | Pneumoperitoneum (perforation) | Surgery + intensive support

Question 17

What X-ray finding is pathognomonic for NEC?

Answer 17

Pneumatosis intestinalis — gas within bowel wall (appears as ‘train track’ or bubbly lucencies).

Question 18

What is the most effective preventive measure for NEC?

Answer 18

Exclusive breastfeeding — provides IgA, lactoferrin, and growth factors that enhance gut integrity and reduce bacterial translocation.