Effectiveness of India ink as a long-term colonic mucosal marker.

We prospectively studied the use of India ink as a long-term or "permanent" mucosal marker as part of a study investigating the natural history of diminutive distal colorectal polyps. Twenty-six patients had 32 India ink tatoos implanted. The tatoo sites of the 19 patients who were followed at least 6 months continued to display intensely stained mucosa at the original sites. No side effects or complications were encountered. India ink appears to be a safe and effective long-term marker for colonic mucosal lesions.