Precise activity assessment of inflammatory bowel disease (IBD) is essential to determine the extent and severity of the disease for further specific therapy. Nevertheless, despite ongoing developments in the field of gastrointestinal endoscopy, the final diagnosis still relies on the interpretation of histopathological features of intestinal biopsies taken during the endoscopic examination. Recently, endocytoscopy (EC) was introduced as a new endoscopic imaging modality, enabling microscopic imaging within the mucosal layer of the gut at a magnification level of up to 1400-fold.

Inclusion Criteria:

• Written informed consent
• Age 18-85 years
• Ability of subjects to understand character and individual consequences of clinical trial
• Subjects undergoing colonoscopy
• Patients with known Crohn´s disease or ulcerative colitis

Exclusion Criteria:

• Inability to provide written informed consent
• Severe Coagulopathy (Prothrombin time < 50% of control, Partial thromboplastin time > 50 s)
• Impaired renal function (Creatinine > 1.2 mg/dl)
• Pregnancy or breast feeding
• Active gastrointestinal bleeding
• Known allergy to methylene blue or toluidine blue
• Residing in institutions (e.g. prison)

Patients with Crohn's disease and ulcerative colitis who underwent colonoscopy.