The aim of this study is to compare the incidence of genito-urinary function depression and anastomotic leak in Laparoscopic Anterior Rectal Resection (LAR) with Total Mesorectal Excision with Ligation if the Inferior Mesenteric Artery at the origin or preserving the Left Colic Artery by a prospective randomized trial.

The level of arterial ligation can affect genito-urinary function (injury to the superior hypogastric plexus), extent (and yield) of lymphadenectomy, distal colonic arterial perfusion (distal colonic arterial perfusion could be deficient due to degenerative disease), sympathic nerve injures. Moreover, colonic stump blood supply together with anastomosis tension are the main factors in developing leaks in rectal surgery and is dependent of the level of ligation. The aim of this study is to compare the incidence of genito-urinary function depression and anastomotic leak in Laparoscopic Anterior Rectal Resection (LAR) with Total Mesorectal Excision with Ligation if the Inferior Mesenteric Artery at the origin or preserving the Left Colic Artery by a prospective randomized trial.

Genito-urinary function will be evaluated with IIEF-5, Internation Consultation Incontinence Modular Questionnarie (ICIQ), Female Sexual Function Index (FSFI), International Index of erectile Function (IIEF) questionnaries and uroflowmetric test pre operatively.

Surgery will be as follow:

The following steps are required in all cases, independently of randomization. The first step consist in the opening of the left part of the gastrocolic ligament and the division of the left part of transverse mesocolon. The splenocolic and phrenocolic attachments are then divided, achieving complete dissection of the left colonic angle. The pelvic peritoneum is opened below the sacral promontory and the hypogastric nerves are identified and preserved. The common iliac veins, the genitofemoral nerve, the gonadic vessels, and the left ureter are successively identified and preserved.

For High Ligation The opening of the peritoneum proceeds cephalad towards the duodenojejunal angle of Treitz, and the mesenteric root is incised 1 cm below the inferior margin of the pancreas. The aortomesenteric window is opened wide and the inferior mesenteric vessels are exposed. The inferior mesenteric artery (IMA) is ligated and divided at 2 cm from its origin. The inferior mesenteric vein is ligated and divided below the pancreatic margin.

For Low Ligation The opening of peritoneum proceeds upward and then laterally towards the sigmoid colon. Left colic artery is identified and preserved while low ligation of the inferior mesenteric artery (superior hemorrhoidal artery) is performed. Lymphadenectomy is carried on medially along the inferior mesenteric artery until 2 cm from the aorta.

For both groups dissection is then carried on windowing Toldt and Gerota fascias till the parietocolic gutter.

Once the descending colonic tract is completely detached from the left parietocolic gutter, dissection of the rectum starts by incision of the peritoneal fold in the pelvis. Total Mesorectal Excision (TME) is then performed according to the principles of Heald.

Colonoscopy will be performed 30 days after surgery to evaluate the anastomosis (leakage, signs of ischemia. Accurate description and pictures of the anastomosis will be produced. IIEF-5, ICIQ, FSFI, International Index of erectile Function (IIEF) and uroflowmetric test will be performed 1 and 9 months post-operatively

Inclusion Criteria:

• middle or low rectal cancer (from 0 to 12 cm from the anal verge), American Society Anesthesiologist (ASA) I II III, Body Mass index (BMI) lower than 30.

Exclusion Criteria:

• prior surgery on the abdominal aorta,
• conversion to laparotomy,
• intraoperative decision for colostomy.