Bowel preparation for colonoscopy requires the administration of large amounts of fluids that can cause fluid and electrolyte disturbances and volume overload, especially in patients with advanced renal failure. Polyethylene glycol-based regimens are considered safe, even in patients with advanced renal failure. However, the incidence of adverse effects (AEs) in routine clinical practice is unknown. The main objective of this study is to carry out a prospective, observational, multicenter clinical registry of renal AE of the preparation for colonoscopy, in patients with advanced renal failure, within the usual clinical practice of the preparation. Variables related to kidney function, bowel-cleansing efficacy, and tolerance will also be recorded. A segmented analysis will be performed in patients with substitutive renal therapy (hemodialysis or peritoneal dialysis).

Introduction: Bowel preparation for colonoscopy requires the administration of large amounts of fluids that can cause fluid and electrolyte alterations and volume overload, especially in patients with advanced renal failure. Routine clinical practice of bowel preparation with polyethylene glycol-based regimens, including in patients with advanced renal failure, is considered safe. The hydroelectrolytic AEs and worsening of renal failure are generally mild and transient. However, the incidence of AEs in routine clinical practice is unknown, because there is no prospective record of the incidence of renal AEs in these patients.

Objectives:

1. Principal. To carry out a clinical registry of the renal AEs of the preparation for colonoscopy, in patients with advanced renal failure, within the usual clinical practice of the preparation.

2. Secondary:

   • Study the efficacy of intestinal cleansing using the Boston bowel preparation scale.
   • Study the patient-reported experience measures (PREMs) in terms of tolerability and acceptance of bowel preparation.

Study of the population and sample size: Outpatients with a scheduled colonoscopy for any indication and with moderate or severe renal impairment. Ages: 18-80, excluding partial colectomy, severe constipation, active intestinal disease, severe heart or liver failure, pregnancy or lactation, and refusal to authorize the clinical record of information. We calculated a sample size of 237 subjects to show an incidence of renal AD of 10%, with a precision of 4%.

Methods: Identify patients with a scheduled colonoscopy who present advanced renal failure, in the 60 days prior to the colonoscopy. Carry out a prospective, observational, multicenter clinical registry of the routine clinical practice of preparation for colonoscopy. Variables related to renal function, the efficacy of intestinal cleansing, and tolerance will be recorded. A segmented analysis will be performed in patients with substitutive renal therapy (hemodialysis or peritoneal dialysis). The data will be collected on the REDCap-AEG online platform, which can be accessed by researchers from each center through an identification code, respecting the current Organic Law on Data Protection.

Inclusion Criteria:

• Outpatients or hospitalized patients with previously scheduled colonoscopy with any indication: screening, follow-up or symptoms.
• Diagnosis of stage 3B-5D chronic renal failure (creatinine clearance less than 45 ml / min / 1.73 m2).

Exclusion Criteria:

• Age less than 18 years or greater than 80 years
• Partial or total colectomy
• Severe constipation
• Active inflammatory bowel disease
• Severe hepatic impairment (Child Pugh Classification C)
• Pregnancy or breastfeeding
• Refusal to authorize the clinical registration of the information

Outpatients with a scheduled colonoscopy for any indication and with moderate or severe renal impairment