Necrotising Enterocolitis
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Direct answer
Necrotising enterocolitis is the gastrointestinal catastrophe of the preterm neonate: gut barrier failure with bacterial invasion, chiefly in low and very low birth weight infants, presenting with feed intolerance, abdominal distension and blood in the stool, and defined radiologically by pneumatosis intestinalis. Bell staging grades severity from suspected (stage I) through definite (stage II) to advanced disease with perforation or shock (stage III). Stages I-II are treated medically — fasting, nasogastric decompression, broad-spectrum antibiotics with anaerobic cover, and serial films every 6-8 hours. Surgery is reserved for perforation, a fixed dilated loop, abdominal wall erythema or deterioration despite maximal medical therapy — by primary peritoneal drainage in the smallest unstable babies, or laparotomy with resection and stoma in the rest.
What you must remember
- Risk profile: prematurity and low birth weight dominate; term neonates with congenital heart disease, perinatal asphyxia or polycythaemia form the smaller second group — and human milk feeding is protective.
- Clinical lead: increasing gastric aspirates and abdominal distension with tenderness, gross or occult blood per rectum, temperature instability, apnoea and bradycardia; thrombocytopenia and metabolic acidosis mark progression.
- Radiology in order of menace: dilated loops with bowel wall thickening, then pneumatosis intestinalis (the hallmark, usually ileocaecal and colon), portal venous gas, and free air — the "football" and falciform ligament signs on supine films.
- Bell framework: stage I suspected (clinical), stage II definite (pneumatosis or portal venous gas, with IIA systemically well and IIB toxic), stage III advanced (IIIA suspected perforation, IIIB proven).
- Medical bundle: fasting with orogastric decompression for 7-10 days in established disease, intravenous fluids and nutrition, and antibiotics covering gram-negatives and anaerobes (for example ampicillin, gentamicin and metronidazole).
- Surgical triggers: free intraperitoneal air, a fixed dilated loop unchanged over serial films, abdominal wall erythema or induration, clinical deterioration despite 24-48 hours of maximal therapy, and a positive paracentesis.
- Operative choices: primary peritoneal drainage (a right lower quadrant drain under local anaesthesia) for the extremely low birth weight unstable neonate; laparotomy with resection of necrotic bowel and stoma formation for the rest, with second-look strategies for borderline bowel.
- Late business: intestinal stricture develops in a meaningful minority after non-operative resolution, and short bowel syndrome with cholestasis from prolonged parenteral nutrition shadows the survivors.
How the exam tests NEC
Three images carry the marks: pneumatosis (linear or cystic wall lucencies — say "pathognomonic" and mean it), portal venous gas (branching lucencies over the liver, a sign of advanced disease, not by itself an operation), and free air (the operation). The staging question usually hinges on II versus III: systemic toxicity with pneumatosis is still medical; perforation or shock makes it surgical. Expect the management-conflict stem: "baby deteriorating despite 48 hours of medical therapy with a fixed loop" — that phrase, the persistent unchanging dilated loop, is a recognised surgical indication even without free air. Two neonatal differentials recur: spontaneous intestinal perforation (focal, early, often without pneumatosis, in babies on indomethacin or steroids) and sepsis with ileus; paracentesis helps when the picture is equivocal. Finally, the prevention answer examiners reward: human milk, standardised cautious feeding advancement, and infection-control bundles — with probiotic supplementation widely used.
Frequently asked questions
What is the pathognomonic radiological sign of necrotising enterocolitis?
Pneumatosis intestinalis — gas within the bowel wall, appearing as curvilinear or cystic lucencies, usually in ileocaecal region and colon.
What are the surgical indications in necrotising enterocolitis?
Free intraperitoneal air, a persistently fixed dilated loop on serial films, abdominal wall erythema, deterioration despite maximal medical therapy, or positive paracentesis.
What is Bell stage III disease?
Advanced necrotising enterocolitis with systemic shock and suspected (IIIA) or proven (IIIB) intestinal perforation, managed surgically.
How is the extremely low birth weight unstable neonate with perforation managed?
Primary peritoneal drainage — a right lower quadrant drain placed under local anaesthesia — with laparotomy reserved for failure to improve.
Which late complication follows medically treated necrotising enterocolitis?
Intestinal stricture in a meaningful minority, presenting with obstruction weeks later and confirmed on contrast study before resection.