BackgroundTotal Mesorectal Excision (TME) is the standard surgical technique for the treatment of rectal cancer. However, rates of sexual dysfunction ofup to 50% have been described after TME, and rates of urinary dysfunction of up to 30%. Although other factors are involved, the main cause of postoperative genitourinary dysfunction is intraoperative injury to the pelvic autonomic nerves. The risk is particularly high in the inferior mesenteric artery (IMA). The aim of this study is to compare pre- and post-TME sexual dysfunction, depending on the surgical approach usedin the inferior mesenteric vessels: either directly on the IMA, or from the inferior mesenteric vein (IMV) to the IMA.MethodsProspective, randomized,controlled study of patients with rectal adenocarcinoma with neoadjuvant chemoradiotherapy, who will be randomly assigned to one of two groups depending on the surgical approach to the inferior mesenteric vessels. The main variable is pre- and postoperative sexual dysfunction; secondary variables are visualization and preservation of the pelvic autonomic nerves, pre- and postoperative urinary dysfunction, and pre- and postoperative quality of life. The sample will comprise 90 patients, 45 per group.DiscussionThe aim is to demonstrate that the dissection route from the IMV towards the IMA favors the preservation of the pelvic autonomic nerves and thus reducesrates of sexual dysfunction post-surgery.Trial registrationEthical and Clinical Research Committee, Parc Taulí University Hospital: ID 017/315. ClinicalTrials.gov TAU-RECTALNERV-PRESERV-2018 (TRN: NCT03520088) (Date of registration 04/03/2018).