Irritable bowel syndrome — KFP-style written assessment

KFP 1 (10 marks)

A 29-year-old marketing assistant reports two years of lower abdominal cramping relieved by opening her bowels, bloating by evening, and stool alternating between pellet-like and loose. Symptoms daily. No weight loss, no nocturnal diarrhoea, no bleeding. Examination and bloods normal. ^[18]

1. State the diagnosis and its formal criteria basis. (3) ^[18]
2. Which tests are required before confirming, and which are not? (4) ^{[18] [2]}
3. She asks 'how can you be sure it's not something serious?' Answer using the limited-test strategy evidence. (3) ^[2]

Model answers

1. Irritable bowel syndrome, diagnosed positively on Rome criteria: recurrent abdominal pain/discomfort relieved by defecation or associated with altered bowel frequency or form, plus supportive features (bloating, altered passage), for at least six months. NICE frames assessment when pain, bloating or bowel-habit change persists ≥6 months; Rome IV requires symptom onset ≥6 months with recurrence over the last three. ^{[18] [18]}
2. Required for everyone meeting criteria: FBC, CRP or ESR/plasma viscosity, and coeliac serology (tTG ± EMA); faecal calprotectin where IBD is plausible. NOT required: colonoscopy, sigmoidoscopy, ultrasound, barium enema, thyroid function, faecal occult blood, ova/parasites, hydrogen breath tests — these belong only where red flags arise. Her normal bloods already satisfy most of the battery; add coeliac serology and consider calprotectin. ^[18]
3. The biomarker data make a confident positive diagnosis legitimate: with calprotectin ≤40 µg/g and CRP ≤0.5 mg/L the probability of IBD falls below one percent, so adding CRP and calprotectin to Rome symptoms permits confident diagnosis while sparing colonoscopy and its harms. Red-flag absence (no bleeding, weight loss, anaemia, nocturnal symptoms) completes the picture. ^[2]