Endoscopist at different level of experience are to participate. Patients routinely referred to the outpatients department for colonoscopy are asked to participate in a randomised trial where coecal intubation rate and pain experienced by the patient are end-point. Written informed consent is obtained. For each endoscopist, allocated patients are randomised to colonoscopy with no imaging technique (usual care) or using the 3-dimentional imager.