Traditionally these catheters are retained for 7 days, because a higher incidence of urinary retention is related to early removal of the urinary catheter. However, recently Enhanced Recovery After Surgery presents that urinary catheters placed via the urethra can be withdrawn 48 hours after colon/rectal surgery in patients receiving epidural pain relief，but there is no clear data on the incidence of urine retention.Longer retaining time of urethral catheter would induce the urinary tract infection while early removal of urethral catheter is considered to develop acute retention of urine due to lack of sensation when the bladder is full. Taking the comfort and mobility for faster rehabilitation of patients into account, the investigators aim at obtain the optimal removal time of urinary catheter after after laparoscopic anterior resection of the rectum

For a better view to avoid accidental trauma and monitoring kidney function during surgery and in the post-surgery period, patients undergoing abdominal operations will usually have a urinary catheter placed in the bladder before the surgery. Traditionally these catheters are retained for 7 days, because a higher incidence of urinary retention is related to early removal of the urinary catheter. However, recently Enhanced Recovery After Surgery presents that urinary catheters placed via the urethra can be withdrawn 48 hours after colon/rectal surgery in patients receiving epidural pain relief.

Longer retaining time of urethral catheter would induce the urinary tract infection while early removal of urethral catheter is considered to develop acute retention of urine due to lack of sensation when the bladder is full. Taking the comfort and mobility for faster rehabilitation of patients into account, the investigators aim at obtain the optimal removal time of urinary catheter after after laparoscopic anterior resection of the rectum

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Inclusion Criteria:

1. Competent to consent to participate in trial
2. Patients with rectal cancer who underwent total or tumor-specific-mesorectal excision with colorectal or colonanal anastomosis
3. Elective surgery
4. ASA classification of 1~3
5. If male, international prostate symptom score <20.

Exclusion Criteria:

1. Combined pelvic surgery(pelvic lymph node dissection, hysterectomy, salpingo-oophorectomy, posterior vaginectomy, cystectomy, ureteral double-J stenting, ureterectomy, ureteroureterostomy, prostatectomy)
2. Postoperative complications with a Dindo grade III or more
3. Known urinary disease(end-stage renal disease, benign prostatic hyperplasia, neurogenic bladder, malignancy)

Other researchers have access to data in the form of published papers