Irritable bowel syndrome (IBS) is a functional bowel disorder with recurrent abdominal pain and disordered defecation and is one of the most common gastrointestinal problems. In practice, IBS was frequently diagnosed as an exclusion diagnosis for patients with recurrent abdominal pain without an organic cause. Visceral hypersensitivity is the major contributing factor of abdominal pain in IBS. Accordingly, tricyclic antidepressants (TCAs) are widely used for IBS, especially if abdominal pain is a prominent symptom. Indeed, meta-analysis also exhibits the clinically significant efficacy of low dose TCAs in IBS. Nevertheless, over 40% of IBS patients receiving TCAs had no improvement in symptoms after treatment. Theoretically, if TCAs are used for IBS patients with hypersensitivity, its efficacy could be increased.

Although rectal distension test might be used to identify hypersensitive patients with IBS, it has been used only for clinical research because it is painful for the patient. On the contrary, colonoscopy is frequently performed in IBS patients to rule out organic disease and for the purpose of colorectal cancer screening. In a study by Kim and colleagues, IBS patients reported higher pain score after colonoscopy than non-IBS patients. This has prompted the hypothesis that pain scoring during/after colonoscopy could also segregate IBS patients with visceral hypersensitivity showing better treatment response of TCA than those without.

The aims of the present study were to evaluate the colonoscopy-related pain perception and the treatment response of amitriptyline in IBS patients and to investigate the predictive values of the colonoscopy-related pain scale in identifying IBS patients with a response to amitriptyline treatment.

Inclusion Criteria:

• Patients with IBS according to the Rome III criteria

Exclusion Criteria:

• Inflammatory bowel disease or malignancy on colonoscopy.
• Previous abdominal surgery other than appendectomy or cesarean delivery,
• Major psychiatric disorders or Beck Depression Inventory-II score of ≥19
• Significant cardiopulmonary diseases or any malignancies
• Taking pain modulators including selective serotonin reuptake inhibitors (SSRI) or tricyclic antidepressants
• Polypectomy during colonoscopy.

Patients with IBS according to the Rome III criteria were recruited in the outpatient clinic at Samsung Medical Center. Inclusion criteria were age 18-75 years and no evidence of inflammatory bowel disease or malignancy on colonoscopy.