We can not get enough sample size.

The purpose of this study is to compare the clinical outcomes of transanal decompression tube as a bridge to surgery with stent as a bridge to surgery for acute malignant left-sided colonic and rectal obstruction.

Approximately 8-47 % of patients with colorectal cancer will present with colonic obstruction. Left-sided colonic and rectal cancer is responsible for nearly 70% of acute colonic obstruction. Emergency colonic surgery for acute obstruction is associated with a higher mortality and morbidity rate than elective surgery. Preoperative decompression results in a less dilated bowel that is more amenable to an elective surgery. Both transanal decompression tube and stent can serve a good preoperative decompression effect and serve a good bridge to surgery. Investigators aim to compare the clinical outcomes of transanal decompression tube as a bridge to surgery with stent as a bridge to surgery for acute malignant left-sided colonic and rectal obstruction.

Inclusion Criteria:

1. definite diagnosis of left-side colonic or rectal obstruction;
2. symptomatic colonic obstruction for less than 1 week;
3. colonic obstruction caused by a histologically proven malignant colonic tumor

Exclusion Criteria:

1. suspected benign colonic or rectal obstruction;
2. right-side colonic obstruction;
3. patients with signs of peritonitis;
4. dysfunction of blood coagulation, active bleeding, active infection, and significant cardiac or pulmonary disease;
5. patients who do not want to undergo surgery.