Paediatrics: Necrotizing enterocolitis

Necrotizing enterocolitis

Incidence

The most common neonatal surgical emergency. Incidence 1–3/1000 live births (5–10% in VLBW infants). Incidence is reduced 6-fold in preterm infants fed breast milk. Typically a sporadic condition affecting preterm infants (790% of cases), but can be epidemic or occur in term infants. The disease may just involve an isolated area of gut, or be extensive. Distal ter-minal ileum and proximal colon are most frequently affected. Multi-organ failure is associated with diffuse disease.

Cause

Multifactorial. Severe intestinal necrosis is end result of an exaggerated immune response within the immature bowel leading to inflammation and tissue injury. NEC rarely occurs before milk feeding commences, but tim-ing of first feed appears not to be relevant. Predisposing factors:

•   Prematurity.

•   IUGR (causes chronic bowel ischaemia).

•   Hypoxia.

•   Polycythaemia.

•   Exchange transfusion.

•   Hyperosmolar milk feeds.

Presentation

Most common in the second week after birth.

Early

•   Non-specific illness.

•   Vomiting/bilious aspirate from gastric tube.

•   Poor feed toleration (increasing gastric aspirates).

•   Abdominal distension.

Late

•   Additional abdominal tenderness.

•   Blood, mucus, or tissue in stools.

•   Bowel perforation.

•   Shock.

•   DIC; multi-organ failure. AXR shows intestinal distension (see Fig. 6.8).

•   Pneumatosis intestinalis.

•   Hepatic portal venous gas.

•   Signs of intestinal perforation, e.g. free peritoneal gas or gas outlining of falciform ligament (‘football’ sign).

Management

•   Prophylaxis: antenatal steroids and breast milk are protective. Emerging evidence for prevention by administration of probiotic bacteria.

•   Investigations: FBC; U&E; creatinine; coagulation screen; albumin; blood gas; blood culture; AXR; Group and cross match.

•   Stop milk feeds for 10–14 days. Insert gastric tube on free drainage.

•   ‘Bell staging’ (see Table 6.2) may be useful in grading severity.

• IV antibiotics for 10–14 days, e.g. benzylpenicillin, gentamicin, and metronidazole.

• Systemic support: e.g. assisted ventilation, correct BP and DIC, parenteral nutrition (PN).

• Surgical opinion: indications for surgery are GI perforation, deterioration despite above medical treatment (necrotic bowel likely), GI obstruction secondary to stricture formation (late). If localized disease, surgical resection of involved bowel with primary repair.

If more extensive, two stage repair with bowel resection(s) and enterostomy, followed later by intestinal re-anastomosis.

Prognosis

Overall mortality is 722%. Increased mortality is associated with:

• VLBW.

• Extensive intestine involvement.

• Multi-organ failure.

• Intrahepatic portal gas.

Extensive bowel resection may result in short bowel syndrome. Excellent prognosis is seen in those who respond to medical treatment, but subse-quent stricture may develop.