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, either by the same endoscopist or a different one. In the vast majority of situations, tattooing provides accurate localization of lesions for later identification. However, in some cases localization is inaccurate .
This topic review will discuss methods to localize colonic lesions, with a focus on endoscopic tattooing. Other issues related to colonoscopy are discussed elsewhere. (See "Overview of colonoscopy in adults".)
INDICATIONS FOR LESION LOCALIZATION
Localization prior to surgery — Lesions in the colon that require surgical excision may sometimes be palpable or easily recognized during surgery. 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 as the laparoscopist cannot palpate the colon . Thus, it is important to have a marker that can be readily and reliably seen laparoscopically. 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 conversion to an open surgery to find the lesion or resection of an incorrect portion of the colon.
An article comparing lesion localization by colonoscopy and computed tomography (CT) scan noted that preoperative localization was inaccurate for 28.5 percent of lesions, even when the results of CT and colonoscopy were combined . As a result, the authors recommended that tattooing of all suspicious lesions at colonoscopy should be standard practice to prevent inadequate resection and lymphadenectomy, particularly for patients with small lesions or for patients likely to have laparoscopic surgery.