Previous with methylene blue suggested that oral administration may be superior to
conventional spray catheters. The main advantages claimed were better staining due to longer
exposure to the dye, more uniform staining due to normal position of the intestines (during
conventional chromocolonoscopy, patients are lying on one side), and a quicker and more
comfortable procedure for the patients and endoscopy personnel.
Using food-grade dyes would enable higher dye loads and lower systemic side effects.
Food grade dyes will be administered orally during preparation with KleanPrep (total amount
of 4 liters) in patients undergoing screening colonoscopy.
On day 1 patients will drink 3 l of the preparation solution, the last liter together with
the last dose of dye will be administered 5 hours before scheduled colonoscopy.
- quality of mucosal staining of colon (assessed by questionnaire)
- adenoma detection rate
- adverse events
- time of colonoscopy