Endoscopic Examination in Irritable Bowel Syndrome
Colonoscopy has no role in IBS except for patients with alarm features or those with IBS-D who have specific risk factors for microscopic colitis. 1
When Endoscopy is NOT Indicated
The yield of colonoscopy in typical IBS patients is extremely low, and there is no evidence that patients derive reassurance from a normal examination. 1 For patients meeting Rome IV criteria with typical symptoms and no alarm features, the diagnosis is secure without endoscopy—particularly for IBS-C and IBS-M subtypes. 1
Do not perform colonoscopy for:
- Patients under 45 years with typical IBS symptoms and no alarm features 1
- Reassurance purposes (this does not work) 1
- Routine diagnostic workup in established IBS 1
When Endoscopy IS Indicated
Alarm Features Requiring Urgent Colonoscopy 1
- Rectal bleeding
- Unintentional weight loss
- Family history of colorectal cancer or inflammatory bowel disease
- Age ≥45 years at symptom onset 1
- New onset symptoms in older patients
Important caveat: Up to 80% of IBS patients report at least one alarm symptom, so clinical judgment is essential—the diagnostic performance of alarm features is modest. 1
IBS-D with Risk Factors for Microscopic Colitis 1
Perform colonoscopy with biopsies specifically to exclude microscopic colitis when the following risk factors are present:
- Female sex
- Age ≥50 years
- Coexistent autoimmune disease
- Nocturnal or severe, watery diarrhea
- Duration of diarrhea <12 months
- Weight loss
- Use of NSAIDs, PPIs, SSRIs, or statins
Critical technical point: All patients with diarrhea undergoing sigmoidoscopy or colonoscopy should have biopsies taken even if the mucosa appears normal, as microscopic colitis cannot be diagnosed visually. 1
Alternative Investigations for Atypical IBS-D
For patients with IBS-D and atypical features (nocturnal diarrhea, prior cholecystectomy), consider testing for bile acid diarrhea with SeHCAT scanning or serum 7α-hydroxy-4-cholesten-3-one rather than proceeding directly to colonoscopy. 1
Management After Endoscopy
Once a functional diagnosis is established through appropriate evaluation, the incidence of new organic diagnoses is extremely low. 1 Focus should shift to:
- Clear communication of IBS as a disorder of gut-brain interaction with benign prognosis 1
- Symptom-directed treatment rather than repeated investigations 2
- Early consideration of psychological therapies (gut-directed CBT or hypnotherapy) rather than waiting for multiple drug failures 1
Avoid the pitfall of repetitive, anxiety-provoking serial testing once the diagnosis is secure. 1