Precise localization of lesions within the colon is essential in a number of clinical circumstances, particularly when surgical resection is required or a lesion needs to be reinspected at a later date. However, erroneous colonoscopic localization of intracolonic tumors has been described in up to 13 percent of cases .
This topic review will discuss methods to localize colonic lesions, with a focus on colonic tattooing with a permanent marker.
INDICATIONS FOR LESION LOCALIZATION
Localization prior to surgery — Lesions in the colon that require surgical excision may sometimes be palpable during open laparotomy. However, small lesions and those that have been previously removed colonoscopically can be difficult to localize. Even large lesions may not be palpable by the surgeon if they are soft and compressible .
This problem is particularly important for patients undergoing laparoscopic-assisted surgical colonic resection. Unlike open laparotomy, the laparoscopist cannot palpate the colon . Thus, it is important to have an easily visible marker that can be seen through the telescopic lens of the laparoscope. It is not sufficient for the endoscopist to state that "a lesion is in the transverse colon," since more specific localization is needed to avoid a subsequent open surgery to find the lesion.
An article comparing lesion localization by colonoscopy and CT scan  stated that "inaccurate pre-operative localisation occurred in 28.5 percent of all lesions even when CT and colonoscopy were combined. We have therefore recommended that colonic tattooing of all suspicious lesions at colonoscopy with [a tattoo] should be standard practice in our institution to prevent inadequate resection and lymphadenectomy, especially in patients with screen-detected small lesions and in patients likely to have laparoscopic surgery."