Extended Total Mesorectal Excision Based on the Avascular Planes of the Retroperitoneum for Locally Advanced Rectal Cancer with Lateral Pelvic Sidewall Invasion

INTRODUCTION: It has been considered difficult to achieve en bloc resection in cases of locally advanced rectal cancer with lateral pelvic sidewall invasion. The present study demonstrates a novel surgical procedure for these tumors. TECHNIQUE: There are 3 avascular planes of the retroperitoneum in the pelvic sidewall. Two visceral pelvic fasciae, namely the ureterohypogastric fascia and umbilical prevesical fascia, and the parietal pelvic fascia can be identified. In addition, the key structures of these fasciae, the ureter, umbilical artery, and external iliac vessels, can be identified transperitoneally before any dissection. Thus, these 3 avascular planes can be dissected without resorting to dissection of the retrorectal space. The key steps to this technique are: 1) after dissection from the side opposite to the site of tumor invasion to the dorsal side of the rectum, the avascular planes of the retroperitoneum among the 3 above-mentioned fasciae are dissected; and 2) the retrorectal space and pelvic sidewall space are connected by sharp dissection. RESULTS: Recognizing the 3 above-mentioned fasciae enables the dissection of the avascular planes of the pelvic sidewall, which helps to achieve en bloc dissection in cases of locally advanced rectal cancer with lateral pelvic sidewall invasion. CONCLUSION: The pelvic sidewall could be divided into 3 areas based on the visceral pelvic fasciae, which has helped to achieve en bloc dissection in cases of locally advanced rectal cancer with lateral pelvic sidewall invasion.