Spontaneous Intestinal Perforation of Prematurity

Spontaneous intestinal perforation of prematurity is a focal, isolated perforation of the distal small bowel in extremely preterm infants, occurring without the widespread necrosis and pneumatosis of necrotising enterocolitis.

It affects about 1 to 5% of extremely low birth weight infants. Onset is usually between days 3 and 14, often before or soon after the start of enteral feeds.

Risk factors are gestation under 28 weeks, birth weight under 1000 g, early indometacin exposure, particularly with postnatal corticosteroids, hypotension needing inotropes, and chorioamnionitis. Early ibuprofen carries lower but not absent risk.

A single, punched out perforation on the antimesenteric border of the terminal ileum is typical, with healthy bowel on either side. Multiple perforations occur less often.

Pathophysiology.

Immature intestinal muscle and a thin wall are vulnerable to focal ischaemia. Vasoconstriction from indometacin and reduced mucosal perfusion with corticosteroids and hypotension produce a localised defect.

Feeds and bacterial invasion play a lesser role than in necrotising enterocolitis, which explains the usual absence of pneumatosis.

• Sudden abdominal distension, often with bluish or grey discolouration of the abdominal wall.
• Feeding intolerance, bilious aspirates, apnoea, hypotension and increased ventilatory needs.
• Tense abdomen with absent bowel sounds in advanced cases.

Red flags.

• Abdominal wall discolouration with shock.
• Respiratory failure from raised intra-abdominal pressure.

• Abdominal X-ray: free intraperitoneal air (a football sign, double bowel wall outline or a lucent liver) without pneumatosis. Free air can be absent, so a lateral decubitus film or ultrasound showing echogenic ascites helps.
• Blood count, CRP, culture, gas, lactate, coagulation and platelets.
• Peritoneal fluid culture, including fungi.

Differential diagnosis. Necrotising enterocolitis (later onset, pneumatosis, feed related), meconium obstruction of prematurity, malrotation with volvulus, gastric perforation, focal ileal atresia and meconium peritonitis.

Immediate.

• Stop enteral feeds, pass a nasogastric tube for decompression, give IV fluids and parenteral nutrition, and provide respiratory and circulatory support. Give 10 mL/kg boluses of 0.9% sodium chloride for hypovolaemia.
• Broad spectrum antibiotics for 7 to 14 days. A representative regimen for an infant under 30 weeks in the first week of life is ampicillin 50 mg/kg IV every 12 hours, gentamicin 5 mg/kg IV every 48 hours with levels directing later doses, and metronidazole 15 mg/kg IV loading then 7.5 mg/kg every 12 hours. Intervals shorten with higher gestation and postnatal age.
• Consider empirical antifungal cover because of the risk of Candida peritonitis.
• Correct coagulopathy and thrombocytopenia before surgery.

Operative or drain management.

• Bedside peritoneal drain under local anaesthesia and sedation is an option in unstable infants. Laparotomy is needed when the infant fails to improve within 24 to 48 hours, or when drainage cannot control sepsis.
• Laparotomy involves local repair, resection with stoma, or primary anastomosis, directed by bowel condition and stability. Survival and neurodevelopmental outcomes are similar for drainage and laparotomy.

Monitoring. Blood pressure, perfusion, urine output, gases, lactate, glucose, electrolytes and culture results. Gentamicin levels before the third dose.

Referral and escalation. Urgent paediatric surgical review at diagnosis. Transfer to a surgical neonatal centre when not available locally.

Special groups. Infants under 750 g have higher mortality, parenteral nutrition associated cholestasis and neurodevelopmental impairment, so need close long term follow up.