Makindo Medical Notes

Related Subjects: |Metabolic acidosis

Necrotising Enterocolitis affects about 5% of infants with birth weights less than 1,500g. It typically presents with symptoms such as abdominal distension, bloody stools, pneumatosis intestinalis, and bile-stained vomiting.

About

• NEC primarily affects premature neonates, often resulting in severe complications.
• Can lead to bowel perforation, peritonitis, and septic shock.
• Mortality rate ranges from 20-30%, depending on the severity and timely intervention.

Aetiology

• Immature intestinal mucosa, making infants more susceptible to injury.
• Combination of intestinal ischaemia/reperfusion injury, infection, and underdeveloped immune responses.
• Release of inflammatory mediators like PAF, TNF, and cytokines which lead to intestinal damage.

Risk Factors

• Low birth weight and extreme prematurity.
• Formula feeding rather than breastfeeding.
• Underlying congenital heart disease.
• Polycythaemia and conditions like Patent Ductus Arteriosus (PDA) that reduce systemic output.
• Medications: Indomethacin (decreases intestinal perfusion) and steroids when combined with indomethacin.
• Use of umbilical arterial or venous catheters positioned near mesenteric arteries.
• Additional risks include maternal cocaine exposure, respiratory distress syndrome, and bacterial overgrowth from enteral feeds.

Clinical Presentation

• Feeding difficulties or persistent vomiting.
• Bile-stained vomit, swollen and tender abdomen.
• Blood-stained stools and absent bowel sounds.
• Signs of perforation: rigid abdomen, tenderness, and general deterioration.
• Additional findings: abdominal distension, mass formation, wall edema, ascites, and crepitus in the abdominal area.

Investigations

• Blood Tests: Elevated WCC, CRP, lactate, low platelets, and signs of DIC in coagulation profile.
• U&E: Indicators of acute kidney injury (AKI) and low sodium levels.
• Blood Gas: Metabolic acidosis.
• Imaging: Abdominal X-ray (AXR) for bowel wall edema, gas in bowel wall, portal vein gas, and free air in cases of perforation. A lateral decubitus view may highlight air over the liver.

Staging (Bell's Criteria)

• Stage 1 (Suspected NEC): Gastric residuals, abdominal distension, occult or visible blood in stool, temperature instability, apnoea, bradycardia; X-ray may show mild distension.
• Stage 2 (Definite NEC): Mild to moderate illness, absent bowel sounds, tenderness, pneumatosis intestinalis or portal venous gas, metabolic acidosis, low platelets.
• Stage 3 (Advanced NEC): Severe illness, marked distension, peritonitis signs, hypotension, respiratory and metabolic acidosis, DIC, pneumoperitoneum (indicative of bowel perforation).

Management

• Resuscitation: Infants may require circulatory support, acid/base correction, intubation, and ventilation. Morphine may be given for pain relief.
• Initial Support: For suspected or proven NEC cases:
  • Keep Nil by Mouth (NBM) and initiate IV feeding.
  • Administer antibiotics, TPN, and IV fluids as supportive measures.
  • Place an NG tube for decompression.
• Surgical Intervention: Immediate surgical consultation for potential bowel resection. Surgery may be necessary in cases with free air (indicating perforation), although a peritoneal drain may be considered in very low-weight infants. Surgical resection options include primary anastomosis or stoma creation, depending on the extent of necrosis.
• Co-Management with PDA: In infants with PDA, begin medical management and consider surgical PDA closure if needed. Avoid indomethacin in NEC cases due to risks of exacerbating intestinal injury.

Complications

• Peritonitis, leading to sepsis and potentially fatal outcomes.
• Intestinal strictures and potential development of short bowel syndrome.
• Long-term reliance on parenteral nutrition due to extensive bowel resection.

References

• Necrotizing Enterocolitis (NEC) - UCSF Benioff Children’s Hospital