Laparoscopic high anterior resection for rectal cancer with rare variations of the left renal vessels: A case report.

We present a case of rectal cancer with rare variations of the left renal vessels. A man in his 60s underwent endoscopic mucosal resection for an Ip-type lesion in the upper rectum. Histologically, the lesion was a well-differentiated adenocarcinoma that had invaded the deep submucosal layer. Therefore, additional resection of the rectum with regional lymph node dissection was recommended. Preoperative CT revealed rare variations of the left renal vessels. There were two left renal arteries and veins; the caudal left renal artery and vein were located between the inferior mesenteric artery and the abdominal aorta. During the operation, these renal vessels were confirmed, and laparoscopic high anterior resection was performed safely without any injury to these renal vessels. To avoid the risk of unexpected intraoperative injuries, it is important to preoperatively check whether there are any variations in the renal vessels, even before colorectal surgery.