Efficacy of contrast chromoendoscopy of the colon after oral administration of indigo carmine dye

Abstract

Indigo carmine dye is usually spread directly over the colon in many chromoscopic techniques aiming better visualization of a lesion already detected by conventional colonoscopy. Examination of the colon already stained by oral administration of indigo carmine dye may increase detection of small lesions resulting in higher sensibility of the colonoscopy in diagnosing diminutive lesions. Analyze the results regarding the quality of chromoscopic technique and the indigo carmine dye distribution over the colon after oral administration. Fifty patients undergoing colonoscopy were evaluated. A capsule containing 100 mg of indigo carmine dye was offered to these patients 30 min before oral mannitol prep routinely used. The indigo carmine dye contrast effect was graded as bad, regular or good according to preestablished criteria in three segments of the colon: right and left colon and the rectum. In the right colon, good indigo carmine dye contrast effect was observed in only 9 (18.8%) patients, while it was considered regular and bad in 32 (66.6%) and in 7 (14.6%) patients, respectively. A good indigo carmine dye contrast effect was never observed in this series for the left colon or in the rectum. As a matter of fact, no indigo carmine dye was observed in the left colon in 80.9% and in the rectum in 92% of patients in this series. Although it may be simple and desirable, oral administration of indigo carmine dye seems ineffective for enhancing detection of diminutive lesions by chromoscopy as result of poor colonic distribution of indigo carmine dye mainly at distal colonic sites.