Most surgeons suggest the use of fecal diverting to address the high morbidity and mortality associated with anastomotic leakage (AL) in patients with high risk factors on AL who are undergoing anterior resections. Although debate about the use of defunctioning stoma continues, meta-analyses and randomized multicenter trial results support the use of defunctioning stoma in lower anterior resection(LAR). This exploratory study was conducted to evaluate the efficacy and safety of a new diversion method called spontaneously closed cannula ileostomy (SCCI), which was designed to protect rectal anastomosis in patients with high risk factors on AL. Results of SCCI were compared to those of the loop ileostomy (LI) method.

After low anterior resection(LAR), in the LI group, the operation method was done as surgeons all known. In the cannula ileostomy group, a double row of concentric purse-string sutures were placed in the ileum wall using 3-0 absorbable suture. The diameters of the purse-string rings were about 10 mm and 20 mm, respectively. The investigators then made a small incision within the inner purse-string and inserted the trachea cannula into the proximal end of the ileum. The inner purse-string suture then was tied, followed by the outer purse-string suture. The outer purse string should capsulate the inner purse string to prevent leakage. Normal saline was injected into the air bag until the ileum wall began to turn pale. The investigators then pulled the cannula out through the abdominal wall. The incision site in the ileum was approximated to the inner abdominal wall and extraperitonized by fixing the mobilized ileum wall around the cannula to the inner abdominal wall. This was accomplished using 3-4 interrupted sutures.

In the LI group, patients accepted reversal operation at least 3 months after operation if operation condition permission.

In the cannula ileostomy group, the cannula will be removed after 3-4 weeks. If anastomotic leakage occurred, The investigators will keep the cannula until the anastomotic leakage was cured.

Inclusion Criteria:

1. Rectal Tumor After Low Anterior Resection the Anastomosis Located extraperitoneal.
2. Intraperitoneal Anastomosis Who Used of Glucocorticoid or Accepted Neoadjuvant Chemoradiotherapy.
3. Patients Agreed to Undergo the Canula Ileostomy or Loop Ileostomy Procedure

Exclusion Criteria:

1. Bowel Preparation is Satisfied Before Operation(This Means That if Surgeons Find That There is Much Feces Left in the Colon,the Patient Will be Excluded)
2. positive air leakage test
3. fractured anastomotic rings