The study aims to:

1. Determine whether the density of epithelial gaps in terminal ileum of patients with irritable bowel syndrome (IBS) is different from that in inflammatory bowel disease (IBD) patients and normal controls by confocal laser endomicroscopy (CLE).
2. Evaluate the relationship between the density of epithelial gaps and IBS subtypes, and visceral hypersensitivity.

Epithelial cells lining the gastrointestinal tract serve as a barrier between the gut lumen and the body. Previous study has shown that epithelium is punctuated by discontinuities named "gaps". Confocal laser endomicroscopy could be used as a useful tool for detecting epithelial gaps in vivo, and epithelial gap density in terminal ileum of IBD patients was elevated compared with normal control using CLE. So this study aims to determine whether the density of epithelial gaps in terminal ileum of patients with IBS is different from that in IBD patients and normal controls by CLE, and to evaluate the relationship between the density of epithelial gaps and IBS subtypes, and visceral hypersensitivity.

Inclusion Criteria:

• Bowel habits alterations meeting IBS Rome III criteria and indications for colonoscopy investigation
• Patients with history of inflammatory bowel disease
• Asymptomatic individuals for health surveillance or patients for follow up after polypectomy
• Patients complained of hemafecia but colonoscopy revealed only haemorrhoid

Exclusion Criteria:

• Patients with known cancers or abdominal surgery
• Alarm symptoms such as anaemia, gastrointestinal bleeding or obstruction, marked weight loss, abdominal mass
• Patients who are unwilling to sign or give the informed consent form
• Patients who are allergic to fluorescein sodium
• Patients with impaired cardiac, liver or renal function
• Patients with coagulopathy
• Patients with pregnancy or breastfeeding

Patients with indications for colonoscopy in Qilu Hospital outpatient and inpatient department.