Inflammatory Bowel Disease — SAQ

Stem

A candidate is asked to manage a classic presentation of Inflammatory Bowel Disease in an exam setting. Use precise definitions, scores, doses, and decision thresholds.

Core knowledge (model answer backbone)

Inflammatory bowel disease (IBD) is a group of chronic relapsing immune-mediated disorders of the gastrointestinal tract comprising Crohn disease (CD) — transmural inflammation in a skip-lesion distribution anywhere from mouth to anus, frequently involving terminal ileum, with fistula, stricture, abscess and perianal disease — and ulcerative colitis (UC) — diffuse mucosal inflammation continuous from the rectum proximally, presenting with bloody diarrhoea, urgency and tenesmus. A third working group, IBD-unclassified (IBDU) or colonic IBD type-unclassified, is used when differentiation is not possible on initial work-up. Incidence is highest in the second and third decades (a smaller second peak in the seventh decade) in populations of North European, North American, Australasian and now increasingly South Asian and East Asian descent; the global burden has risen dramatically as newly industrialised regions adopt a Western diet and lifestyle. Pathology is driven by an inappropriate mucosal immune response against luminal antigens — particularly the gut microbiome — in a genetically susceptible host (NOD2/CARD15, IL23R, ATG16L1, ECM1, HLA), with impaired mucosal barrier function, dy

Red flags

• More than 6 bloody stools per day with fever, tachycardia, anaemia or raised CRP in a UC patient — acute severe UC, hospitalise for IV steroids, rescue therapy and early surgical referral
• Toxic megacolon (transverse colon diameter above 6 cm on plain film, with systemic toxicity) — NBM, IV fluids and electrolytes, IV steroids, broad-spectrum antibiotics, early surgical referral for colectomy
• Suspected perforation, peritonism or new pneumoperitoneum — free perforation, broad-spectrum antibiotics, IV fluids, emergency laparotomy
• Crohn patient with high swinging fever and a tender abdominal or pelvic mass — intra-abdominal or pelvic abscess requiring cross-sectional imaging, IV antibiotics, percutaneous or surgical drainage before immunosuppression

High-yield structure examiners expect

Cover: Overview & Definition, Classification, Epidemiology & Risk Factors, Pathophysiology, Clinical Presentation, Differential Diagnosis.

Key doses / thresholds (from topic teaching)

• prednisolone 40 to 60 mg daily then taper** for active flares, *
• azathioprine 2 to 2.5 mg/kg daily** for maintenance and steroid
• infliximab 5 mg/kg IV at 0/2/6 weeks then q8w, adalimum
• mg SC then 40 mg q2w, vedolizumab 300 mg IV 0/2/6/q8w, u
• stekinumab 6 mg/kg IV then 90 mg SC q8w)** and **small
• tofacitinib 10 mg BD acute UC then 5 mg BD)** for moderat

Questions

a) Define the condition and give the most important classification or severity framework used in exams. (3 marks)

• Clear one-line definition matching standard teaching.
• Named classification / stages / types with discriminating features.
• One sentence on why classification changes management.

b) Outline pathophysiology in a mechanism chain that explains the main clinical features. (3 marks)

• Initiating insult → intermediate pathway → end-organ effect.
• Link at least two symptoms/signs to mechanism.
• Mention one complication pathway (e.g. shock, perforation, herniation, arrhythmia).

c) List discriminating clinical features and bedside assessment. (3 marks)

• Classic presentation plus one atypical group (elderly, pregnancy, child, immunocompromised).
• Named signs/manoeuvres if relevant.
• What must never be missed on exam/bedside (pregnancy test, airway, glucose, etc.).

d) Investigations with thresholds and one named score if applicable. (3 marks)

• First-line tests and what positive findings mean.
• Gold-standard or definitive investigation when needed.
• Score components reproduced exactly if a named score is standard for this topic.

e) Immediate resuscitation and definitive management with doses where standard. (3 marks)

• ABC / time-critical steps first.
• First-line drug(s) with agent + dose + route (or procedure steps).
• Escalation triggers (theatre, ICU, thrombolysis window, antidote, etc.).
• Disposition and safety-netting.

Marking tips

Full marks require specificity (numbers, names, doses) not generic "give antibiotics/fluids." Regional practice (ICMR / NICE / AHA) may be cited as alternative where relevant.