Mechanical bowel preparation before elective colorectal surgery: a systematic review of global randomized clinical trials PANG Ming-hui, LUO Bin, ZHANG Wei, et al. Department of Gastroenterology，Sichuan Provincial Peoples’ Hospital, Chengdu 610072,China Corresponding author: ZHANG Wei, E-mail: donald zhang65@yahoo.com.cn Abstract Objective To investigate the safety and effectiveness of routine preoperational mechanical bowel preparation (MBP) in patients with colorectal anastomosis. Methods A global electronic and hand searching were carried to identify randomized clinical trials. After quality assessment of all included RCTs, meta-ananysis was performed with Review Manager 4.2.7. Results 12 RCTs with 4992 patients were included. When comparing MBP with None MBP group, the differences in mortality［RR 1.02，95%CI（0.64，1.59），P=0.95］, ananstomotic dehiscence［RR 为1.16，95%CI （0.86，1.55），P=0.33］, reoperation rate［RR 为1.05，95%CI （0.81，1.35），P=0.71］, wound infection［RR 为1.17，95%CI （0.98，1.40），P=0.08］and abdominal abscess ［RR 0.93，95%CI（0.60，1.45），P=0.75］ were of no significance. Conclusion we advise that mechanical bowel preparation before elective colorectal surgery can safely be abandoned.