This is a randomized trial comparing the bladder and sexual function of patients who undergo laparoscopic and robotic assisted rectal resection for rectal cancer~The primary objective of this study is to compare the bladder and sexual functions of patients who undergo laparoscopic and robotic assisted resection for rectal cancer through a randomized controlled trial.~The secondary outcome measures include~The operative outcome in terms of the complication rate, hospital stay and reoperation of the two groups;~The quality of life of the patients and the cost of the two groups~The quality of the resected specimens~The local recurrence rates at two years after the surgery
Hypothesis: the bladder and sexual functions can be better preserved in patients with robotic assisted rectal surgery~This is a randomized trial comparing the bladder and sexual function of patients who undergo laparoscopic and robotic assisted rectal resection for rectal cancer.