Distinctive features of small vessels on the mesorectal and parietal pelvic fascia as important landmarks in guiding precise inter-fascial dissection for low rectal cancer.

Background The confinement of the pelvis and the complexity of pelvic fascial anatomy still pose difficulties in achieving good quality surgery for rectal cancer. We aimed to introduce small vessels on the mesorectal fascia and the parietal pelvic fascia as novel landmarks to aid in the identification of the inter-fascial dissection plane. Besides, the perioperative, survival, and functional outcomes of this surgical technique were reported. Methods We first described that small vessels running on the mesorectal fascia and the parietal pelvic fascia showed distinctive features, which included (1) small vessels on the parietal fascia took the same orientation as the ureter or the sympathetic and parasympathetic nerve; (2) small vessels on the mesorectal fascia were coursing cranially and medially on the anterolateral aspect, and medially and caudally on the posterolateral aspect; (3) small vessels on the mesorectal fascia became invisible at the interface between the pelvic wall and the mesorectal fascia. These features could be applied in fascial identification and separation. Then, we reported the outcomes of low rectal cancer surgery with small vessels-guided technique. Results From 2013 to 2016, a consecutive series of 310 patients with low rectal cancer underwent laparoscopic total mesorectal excision with small vessels-guided technique. The positive rate of circumferential resection margin was 3.2%, and complete mesorectal excision was achieved in 97.8% (303/310) patients. The 3-year overall survival, disease-free survival, and local recurrence rates were 89.4%, 79.7%, and 2.6%, respectively. The urinary function was considered normal in 96.8% of patients, with a moderate dysfunction in 3.2% of patients. Besides, 29.5% of male patients occurred sexual function injury. Conclusion Distinctive features of small vessels on the parietal pelvic fascia and the mesorectal fascia can serve as novel and additive landmarks in guiding precise inter-fascial dissection for low rectal cancer.