Necrotising enterocolitis and spontaneous intestinal perforation — branching viva

Branch 1 — Diagnosis and staging

Examiner: "What is your working diagnosis, and how do you stage it?" ^[1]

The working diagnosis is necrotising enterocolitis. The bubbly bowel-wall lucency is pneumatosis intestinalis, the hallmark radiological sign, and the branching liver lucency is portal venous gas, a marker of severe disease. Using the modified Bell staging (Bell 1978, Walsh and Kliegman 1986), the combination of pneumatosis, portal gas, the systemic instability (apnoea) and the biochemical deterioration places this at Stage IIB — definite, moderate NEC. ^{[1] [2]}

I would move to Stage III if the infant developed shock with acidosis and peritonitis (IIIA, intact bowel) or a pneumoperitoneum (IIIB, perforation). The A/B suffix is the surgical discriminator: A is an intact bowel managed medically; B is perforation or gas requiring surgery. ^[1]

Examiner: "If the infant were instead a day-6 ELBW baby, well apart from an incidental pneumoperitoneum on a routine film, how would your diagnosis change?" ^[7]

That is the picture of spontaneous intestinal perforation (SIP), not NEC. The discriminator is that the SIP infant is haemodynamically stable, has no pneumatosis and no portal gas, and carries the risk profile of an ELBW infant exposed to early postnatal indomethacin combined with glucocorticoid. The distinction matters because SIP is often managed with peritoneal drainage alone and carries a markedly better prognosis than perforated NEC. ^{[7] [11]}