Trial Information

Comparative Efficacy of Water & Indigo Carmine vs Water or Air Method

1. Design: Prospective, single center, patient blinded, randomized controlled trial

2. Methods: Colonoscopy with traditional air insufflation, water exchange or water
exchange plus indigocarmine to aid insertion of colonoscope; split dose bowel
preparation; all patients will receive sedation; assessment of serum electrolytes level
before and after colonoscopy

1. Control method: Traditional air insufflation method.

2. Study methods:

- Water exchange method.

- Water method combined with chromoendoscopy (0.008% indigo carmine).

3. Population to be studied Veterans between age 50 and 75 referred for first time
screening colonoscopy

4. Unit(s) of analysis

1. Primary outcome: overall adenoma detection rate.

2. Secondary outcomes: patient demographic variable and procedure related measures.

5. Sampling strategy: all veterans referred for screening colonoscopy will be offered
enrollment in the study.

1. Sample size calculation. A total of 480 subjects will be recruited and randomized
with 160 in each group.

5. Subject recruitment: patients referred for screening colonoscopy come from three sources.

6. Description of base population and groups to be studied and method of randomization.

Veterans between age 50 and 75 referred for first time screening colonoscopy. After informed
consent, assignment to control or study arm based on computer generated random number codes
stored in pre-arranged opaque envelopes.