Inflammatory bowel disease: SAQ

This boy presents the classic insidious picture of paediatric Crohn disease: months of fatigue and diarrhoea without overt bleeding, growth faltering with a fall in height centile and delayed puberty, iron deficiency anaemia, raised inflammatory markers with hypoalbuminaemia, and perianal skin tags as the easily missed diagnostic clue. The right lower quadrant tenderness and raised faecal calprotectin point to terminal ileal and colonic inflammation. ^[1]

Question 1 (10 marks)

Outline the diagnostic workup you would arrange for this child, including the endoscopic procedures and the supporting investigations. ^[1]

The diagnosis follows the ESPGHAN revised Porto criteria. Ileocolonoscopy with biopsies taken from every segment, including the terminal ileum, is the minimum diagnostic procedure, and upper gastrointestinal endoscopy is also performed at diagnosis in all suspected paediatric IBD, because isolated upper-gut Crohn disease is common in children and is missed by colonoscopy alone. Upper endoscopy may be omitted only when both endoscopy and histology of the ileum and colon are completely normal, which is not the case here. ^[1]

Supporting blood and stool tests complement rather than replace endoscopy. A full blood count confirms the iron deficiency anaemia, C-reactive protein and erythrocyte sedimentation rate confirm ongoing inflammation, and albumin reflects the nutritional deficit. Coeliac serology with total immunoglobulin A excludes a common mimic, and stool studies exclude infection. Faecal calprotectin, already markedly raised, confirms intestinal inflammation and supports the threshold for endoscopy. Thiopurine methyltransferase activity or genotyping should be checked early if azathioprine maintenance is contemplated. ^[1]

Cross-sectional imaging complements endoscopy. Magnetic resonance enterography is the preferred modality for assessing small-bowel Crohn disease, strictures, fistulae, and abscesses, and avoids the radiation burden of computed tomography. Pelvic magnetic resonance imaging is indicated for the perianal disease to delineate any fistula or abscess before treatment. Together these define the disease location, behaviour, and extent that drive the induction and maintenance plan. ^[1]