In a RCT in screening colonoscopy subjects, we will determine if chromoendoscopy using a dilute solution of Indigocarmine (IC) delivered by the water method (study method) will improve adenoma detection rate compared with the water method with plain water alone (control method).

Background: Warm water infusion in lieu of air insufflation (water method) improves overall success of screening colonoscopy and our retrospective data indicate a higher adenoma detection rate. Dye spray methods to improve neoplastic polyp detection such as targeted staining or pancolonic chromoendoscopy have been described.

Aim: In a RCT in screening colonoscopy subjects, we will determine if chromoendoscopy using a dilute solution of Indigocarmine (IC) delivered by the water method (study method) will improve adenoma detection rate compared with the water method with plain water alone (control method).

Methods: After informed consent patients undergoing screening colonoscopy will be randomized to be examined by the study or control method. Study method will employ a 0.008% IC solution. Control method will employ plain water. The water method in both study and control groups will be applied as previously described. The colonoscopy will be performed under sedation. Primary outcome measure: adenoma detection rate; secondary outcome: relevant procedure-related variables.

Inclusion Criteria:

• Adult (≥50 years old
• Male and female patients
• Scheduled for screening colonoscopy
• Consented and accept randomization to study or control method

Exclusion Criteria:

• Patients who decline to participate
• Unable to give informed consent
• Unable to complete questionnaires due to language or other difficulties