The study was aimed to prospectively evaluate the acceptance rate of unsedated colonoscopy, in a setting where routine sedation for colonoscopy is standard practice and to characterize the subset of patients willing to try and potentially completing an unsedated procedure.

Patients were offered to undergo colonoscopy without routine premedication. In case of both acceptance and refusal, a brief questionnaire recording demographics (gender, age, level of education) and clinical features was prospectively recorded in a standard data sheet by one of the four endoscopists at enrollment. Clinical features recorded for each patient included: indication to the procedure, history of abdominal surgery or irritable bowel syndrome, presence of pain as main symptom, chronic use of sedative medications, level of patient's anxiety (none, mild, moderate or severe), main concern about the examination and reason for willing to attempt unsedated procedure.

Inclusion Criteria:

• adult outpatients

Exclusion Criteria:

1. previous colorectal surgery
2. indication to a bi-directional endoscopy
3. indication to a partial examination
4. patients' refusal or inability to provide informed consent and
5. advanced heart, lung, liver or renal disease (American Society of Anesthesiology risk class III-IV)

all consecutive 18-80 year-old outpatients presenting to undergo open-access colonoscopy for routine indications were considered eligible to enter the study.