What is the comprehensive workup and treatment approach for a patient suspected of having Inflammatory Bowel Disease (IBD)?

IBD Workup

The diagnostic workup for suspected IBD requires ileocolonoscopy with multiple biopsies from each colonic segment and terminal ileum, combined with fecal calprotectin testing, inflammatory markers, and cross-sectional imaging to establish diagnosis and assess disease extent. 1, 2

Initial Clinical Assessment

Obtain a detailed history focusing on:

• Pattern and duration of symptoms (chronic diarrhea >4 weeks, nocturnal symptoms, bloody stools, abdominal pain relationship to bowel movements) 1, 2
• Presence of tenesmus, urgency, and weight loss 2
• Extraintestinal manifestations (joint pain, skin lesions, eye symptoms) 1, 3
• Family history of IBD or colorectal cancer 1
• Recent infections, antibiotic use, travel history, and medication exposure 1, 2
• Smoking status (protective in UC, risk factor in CD) 2
• Age of onset (consider genetic testing if symptoms began before age 5 or presentation is aggressive) 1

Mandatory Laboratory Investigations

First-line blood tests include:

• Complete blood count to assess for anemia (common in IBD, absent in functional disease) 1, 2
• C-reactive protein or erythrocyte sedimentation rate (note: 15-20% of active IBD patients have normal CRP) 1, 2
• Comprehensive metabolic panel including urea and electrolytes 2
• Coeliac serology to exclude celiac disease 1, 2

Stool studies are mandatory:

• Stool culture, C. difficile toxin, and ova/parasites to exclude infectious causes before diagnosing IBD 1, 2
• Fecal calprotectin is the cornerstone non-invasive test: levels <50 μg/g effectively rule out IBD; levels ≥250 μg/g indicate high suspicion requiring urgent gastroenterology referral and ileocolonoscopy 1, 2

Endoscopic Evaluation (Reference Standard)

Total colonoscopy with ileoscopy is essential and must include:

• Terminal ileal intubation and biopsies (highest diagnostic value for CD) 1, 2
• Multiple biopsies from each colonic segment (at least 2 per segment), stored in separate containers to map inflammation distribution 4, 1
• Rectal biopsies are mandatory to confirm or exclude rectal involvement 1
• Biopsies from both affected and normal-appearing areas to detect skip lesions in CD 1, 2
• Biopsies even if mucosa appears normal (microscopic colitis can have normal endoscopy) 2

For ulcerative colitis diagnosis:

• Colonoscopy or flexible sigmoidoscopy to assess disease extent (proctitis, left-sided colitis, or extensive colitis beyond splenic flexure) 2
• Document continuous inflammation pattern 1

For Crohn's disease diagnosis:

• Document focal, asymmetric inflammation and skip lesions 2
• Terminal ileal biopsies are critical 1, 2

Histopathologic Confirmation

Pathology requirements:

• Immediate fixation in buffered formalin upon biopsy collection 1
• Serial sectioning to detect focal lesions 1
• Report should follow "PAID" structure: Pattern, Activity, Interpretation, and Dysplasia 1
• Expert gastrointestinal pathologist review for confirmation, especially for dysplasia 1

Cross-Sectional Imaging

MR enterography is the preferred imaging modality:

• Essential at diagnosis to assess small bowel involvement not accessible by endoscopy 1, 2
• Preferred over CT to minimize radiation exposure, especially in young patients requiring repeated investigations 1, 2
• Indicated for suspected small bowel CD, obstructive symptoms, or suspected abscess/fistula formation 1
• Ultrasound can be used for initial assessment but is operator-dependent 1

Critical Pitfalls to Avoid

Do not:

• Rely on CRP alone for diagnosis (approximately 15-20% of active IBD patients have normal CRP) 2
• Defer colonoscopy based on intermediate calprotectin values if clinical suspicion is high based on symptoms or family history 2
• Perform colonoscopy in severe colitis without experienced endoscopist involvement due to higher perforation risk 2
• Diagnose IBD without excluding infectious causes first 1, 2

Differential Diagnosis Considerations

Systematically exclude:

• Infectious colitis (ensure negative stool cultures before diagnosing IBD) 1, 2
• Celiac disease (check serology) 1, 2
• Microscopic colitis (requires biopsies even with normal-appearing mucosa) 2
• Bile acid diarrhea (consider SeHCAT testing or therapeutic trial in diarrhea-predominant cases) 1
• Small intestinal bacterial overgrowth and carbohydrate intolerance 1

Multidisciplinary Team Approach

Diagnosis requires collaboration between:

• Gastroenterologists, pathologists, and radiologists working together 1
• Minimum MDT per 250,000 population should include: two gastroenterologists, two colorectal surgeons, 2.5 IBD nurses, one histopathologist, one radiologist, and one pharmacist 1