[A Case of Precaval Right Renal Artery].

Understanding renal artery tortuosity is important in urological surgery. The right renal artery normally runs dorsal to the inferior vena cava. In precaval renal artery, vascular anomaly, the right renal artery, branching from the abdominal aorta, runs ventral to the inferior vena cava. Furthermore, the precaval renal artery is often an accessory artery and rarely a single main artery. Preoperative identification of these anomalies is important for successful surgery. Herein, we report a case of 71-year-old woman who visited our department after right renal cancer was detected on computed tomography (CT) performed to investigate the sigmoid colon cancer. Per CT findings, the right renal artery ran ventrally to the inferior vena cava and was the single main artery. The right renal artery abnormality was confirmed preoperatively, and robot-assisted laparoscopic partial nephrectomy (RAPN) was completed without any major intraoperative complications. Approximately 25-40% of the renal arteries are estimated to run abnormally. Among these, the prevalence of a precaval right renal artery is estimated to be 0.8-5.0%, and most are collateral arteries. Furthermore, the precaval right renal artery rarely serves as the single main artery. This report aims to describe a case in which RAPN was performed safely in a patient with a single main artery, the precaval right renal artery, as the course of the right renal artery was known preoperatively.