<qa>  What is the Boston Bowel Preparation Scale?Endoscopic technique: All colonoscopies will be performed after the patient had undergone standard bowel preparation using either polyethylene glycol electrolyte lavage solution. Initially a routine white light colonoscopy will be performed in IBS and healthy control patients, using a Pentax scope Pentax EC-387CILK, Tokyo, Japan with great care not to damage the epithelium. The Boston Bowel Preparation Scale and inflammation changes will be recorded. 