Surgical usefulness of indocyanine green as an alternative to India ink for endoscopic marking

India ink has been commonly used for preoperative colonic tattooing, but various complications have been reported. This study aimed to evaluate the usefulness of indocyanine green (ICG) marking as a replacement for India ink. This study enrolled 40 patients who between January 2005 and February 2006 underwent laparoscopic or open surgery for colorectal lesions considered difficult to locate intraoperatively. Because one patient had a history of allergy to iodinated contrast material, metal clipping was used instead of ICG to mark the lesion. Endoscopists injected 5 ml of ICG suspension and saline solution adjacent to the lesion at duplicate locations to evaluate the visibility, duration, and adverse effects of the dye. For 39 patients, the date of the preoperative colonoscopy was not set for examination of the appropriate interval between endoscopic marking and the surgical operation. The median interval between ICG marking and surgery was 4 days (range, 1-73 days). All 29 patients who underwent surgery within 8 days after marking had positive green ICG staining at the time of surgery. After 9 days or more, however, positive staining was seen clearly in only two of the remaining 10 patients. The staining tended to grow weaker and fainter over the time course, eventually dissipating. No perioperative adverse reactions to the dye were observed. This study supports the use of ICG as a safe technique that can be identified reliably during operations performed within 8 days after endoscopic injection.