About 50-70% only of inpatients who undergo colonoscopy have an adequate bowel cleansing, which is far below the recommended threshold of 90%. Variables associated to inadequate colon preparation have not been assessed yet. Identifying such variables would allow to augment the diagnostic yield of colonoscopy, and also to reduce costs related to the need to repeat colonoscopy. Aim of the present study is to find variables independently associated to an inadequate bowel cleansing and to subsequently build and validate a predictive model, which could prove useful in clinical practice to identify hard-to-prepare inpatients. Secondary endpoints are (i) to assess the proportion of patients with inadequate colon cleansing, (ii) to run a cost-effectiveness analysis between patients with adequate cleansing and patients who need to repeat colonoscopy. Patients undergoing urgent colonoscopy, and patients who take the preparation at home will be excluded.

Inclusion Criteria:

• Inpatient ≥18 y.o. who are scheduled elective colonoscopy during hospitalization irrespective of the indication.

Exclusion Criteria:

• Urgent colonoscopy
• Patients who are not hospitalized when taking bowel preparation or when undergoing colonoscopy

Adult patients hospitalized in 12 Centers in Italy, who are scheduled elective colonoscopy irrespective of the indication.