To study the cases of colorectal cancer with incomplete obstruction which was revealed by preoperative colonoscopy.

All included cases of colorectal cancer with incomplete obstruction which was revealed by preoperative colonoscopy were studied retrospectively between April 2009 and April 2019 in the First Hospital of Jilin University. According to the location of the tumors, all cases were divided into two groups: right-sided group (group R) and left-sided group (group L), and the relevant clinical and pathological data were compared and analyzed.

Totally 208 cases were included, with group R and group L including 66 and 142 cases respectively. For the quality of colon cleansing of preoperative colonoscopy, group L was better than that of group R (χ²=52.905, P＜0.01). A total of 77 cases were reexamined by colonoscopy, accounting for only 37.0%, and the median follow-up time was 8.0(6.0~12.0) months. In group L, one case of primary colorectal cancer was found. There was no significant difference between the two groups in terms of the proportion of newly discovered polyps (53.8% vs. 56.9%, χ²=0.064; P = 0.801). For the distribution of polyps on the anal side of the anastomosis, the incidence of cases in group R was significantly higher than that in group L (53.8% vs.7.8%, χ²=20.346; P＜0.01). The local recurrence rate of middle and low rectal cancer was 11.8%, which was higher than that of other colorectal cancer (χ²=7.247, P＜0.05).

For patients suffering from colorectal cancer with incomplete obstruction which was revealed by preoperative colonoscopy, early post-operative colonoscopy should be offered. Missed polyps should be noted in the follow-up of colonoscopy after right hemicolectomy. For the left-sided colorectal cancer, the possibility of multiple primary cancers should be excluded. Especially, for the middle and low rectal cancer, local recurrence of the anastomosis should be paid attention to after anus preserving operation, so as to improve the survival of such patients.