Intraoperative localization of occult colorectal tumors during laparoscopic surgery by magnetic ring markers-a pilot study.

Purpose: Intraoperative localization of small tumors or malignant polyps has been an important issue in laparoscopic colon surgery. We have developed a new method for preoperative endoscopic tumor marking using a ring-shaped magnetic marker.

Methods: In a pilot study, 28 patients with small colonic (n = 23) or rectal tumors (n = 5) underwent endoscopic magnetic clipping prior to laparoscopic resection. A cap carrying a high-power neodymium ring magnet was mounted on the tip of a colonoscope. Near the lesion, the ring magnet was released and clipped to the colorectal wall. Standard laparoscopic instruments were used to find the magnet intraoperatively.

Results: Endoscopic fixation of a ring magnet next to the tumor by clipping was technically feasible in all 28 patients. Intraoperative localization of the marked lesions was successful in 27 of 28 patients (96 %). All patients underwent magnet-guided radical laparoscopic resection of the tumor with an average proximal and distal resection margin of 101 and 63 mm, respectively. In one case, the magnet could not be found due to preoperative migration. Surgical complications related to magnetic clip application or intraoperative tumor localization were not observed. However, there was one case with an intraoperative perforation of the colon by the magnet, which was obviously caused by unchecked action with a laparoscopic instrument.

Conclusions: Preoperative endoscopic labeling of colonic lesions with on-the-scope magnetic markers is simple and safe. Intraoperative tumor localization during laparoscopic colorectal surgery can be achieved reliably without additional equipment such as ultrasound or fluoroscopy.