Application of ultrasonography to high-tie and low-tie vascular ligation of the inferior mesenteric artery in laparoscopic colorectal cancer surgery: technical notes

Background: Two ligation techniques can be applied in laparoscopy for left-sided colorectal cancer: (1) high-tie (HT), transection at the level of the inferior mesenteric artery (IMA); and (2) low-tie (LT), transection below the IMA, at the level of superior rectal artery (SRA), preserving the left colic artery (LCA). However, even with preoperative images, it can still be a challenge to identify these structures due to intraoperative individual conditions. In this study, we assess the use intraoperative ultrasonography (IOUS) to aid us in identifying the IMA and its branches to the SRA, LCA, and sigmoid artery. Methods: We performed IOUS in 18 patients diagnosed with left-sided colorectal cancer. Preoperatively, a three-dimensional computed tomography (3D-CT) angiography was obtained in majority of the patients, to visualize the IMA and its branches. Two patients were contraindicated to receive a contrast study, hence, was unable to undergo 3D-CT angiography. The resected specimen was grossly examined for the study. The bifurcation types were identified and compared using different modalities: preoperative 3D-CT, IOUS, and gross examination of the resected specimen. Results: The branching of the IMA revealed by IOUS was consistent to the findings preoperatively by the 3D-CT and postoperatively by the resected specimen. The IOUS result of the two patients without preoperative 3D-CT evaluation was also consistent with the post-operative bifurcation type. Conclusions: IOUS is an easy and feasible modality which aids in detecting the branching of the IMA during LT and HT ligation in laparoscopic left-sided colorectal surgery. It can serve as an adjunct modality for 3D-CT angiography and can also be considered a safe alternative option for cases wherein 3D-CT angiography is unavailable.