Adequate bowel preparation for colonoscopy has an extremely relevant impact on diagnostic yield and procedural success. The guidelines recommend an adequate colon cleansing rate of at least 90% of procedures. It has been shown that patients with inadequate colon cleansing history have a high probability of not reaching an adequate bowel preparation again.

Surprisingly, no evidence-based recommendations are available regarding bowel preparation in the patient with inadequate colon cleansing history. Therefore, identifying the factors associated with repeated inadequacy of bowel cleansing is crucial in order to define the best preparation strategy in this subset of patients. The implications for patients and for healthcare system are many: improving the quality of bowel preparation would reduce the need to repeat colonoscopy and the risk of conducting unreliable examinations. Furthermore, it would reduce the costs for the healthcare system by avoiding to overload endoscopic units.

Inclusion criteria:

Outpatient and hospitalized patients, adults, candidates for colonoscopy for any pathology, as part of the normal care process, with the need to repeat bowel preparation due to inadequate cleansing.

Exclusion criteria:

• Emergency regime
• Inability to obtain consent
• Refusal of the patient

Primary end-point:

Identification of factors independently associated with repeated inadequate colon cleansing after inadequate bowel preparation at previous colonoscopy, and consequent development (and validation) of a predictive model.

The colon cleansing will be evaluated according to the Boston Bowel Preparation Scale (BBPS), which assigns a score from 0 (presence of solid stools) to 3 (excellent visualization of the colonic mucosa) for each of the three main segments of the colon, i.e. right colon, transverse colon and left-rectum colon. Colon cleansing will be judged inadequate in case of a total score <6 or a score <2 even in only one of the colic segments.

Secondary end-point:

• Assess the prevalence of repeated inadequate bowel cleansing in the patient with previous inadequate cleansing

Inclusion Criteria:

• Outpatients or hospitalized patients
• adults
• candidates for colonoscopy for any pathology, in the normal pathway of care, with the need to repeat the bowel preparation due to inadequate colon cleansing.

Exclusion Criteria:

• Emergency regimen
• Inability to obtain consent
• Patient refusal

Outpatient and hospitalized adult patients, candidates for colonoscopy for any pathology, in the normal pathway of care, with the need to repeat the bowel preparation due to inadequate colon cleansing.