OBJECTIVETo explore the risk factors and clinical features of delayed anastomotic fistula (DAF) following sphincter-preserving operation for rectal cancer.

METHODSClinical data of 1 594 patients with rectal cancer undergoing sphincter-preserving operation in our department from January 2008 to May 2015 based on the prospective database of Dpartment of Colorectal Surgery, Fujian Medical University Union Hospital were retrospectively analyzed. Sixty patients(3.8%) developed anastomotic fistula. Forty-one patients (2.6%) developed early anastomotic fistula (EAF) within 30 days after surgery while 19(1.2%) were DAF that occurred beyond 30 days. Univariate analyses were performed to compare the clinical features between EAF and DAF group.

RESULTSDAF was diagnosed at a median time of 194(30-327) days after anastomosis. As compared to EAF group, DAF group had lower tumor site [(6.1±2.3) cm vs. (7.8±2.8) cm, P=0.023], lower anastomosis site [(3.6±1.8) cm vs. (4.8±1.6) cm, P=0.008], higher ratio of patients receiving neoadjuvant chemoradiotherapy (84.2% vs. 34.1%, P=0.000), and receiving preventive stoma (73.7% vs. 14.6%, P=0.000). According to ISREC grading system for anastomotic fistula, DAF patients were grade A and B, while EAF cases were grade B and C(P=0.000). During the first hospital stay for anastomosis, DAF group did not have abdominal pain, general malaise, drainage abnormalities, peritonitis but 8 cases(42.1%) had fever more than 38centi-degree. In EAF group, 29 patients(70.7%) had abdominal pain and general malaise, and 29(70.7%) had drainage abnormalities. General or circumscribed peritonitis were developed in 25(61.0%) EAF patients, and fever occurred in 39(95.1%) EAF cases. There were 13(68.4%) cases with sinus or fistula formation and 9(47.4%) with rectovaginal fistula in DAF group, in contrast to 5 (12.2%) and 5 (12.2%) in EAF group respectively. In DAF group, 5 (26.3%) patients received follow-up due to stoma (no closure), 5 (26.3%) received bedside surgical drainage, while 9(47.4%) patients underwent operation, including diverting stoma in 3 patients, Hartmann procedure in 1 case, intersphincteric resection, coloanal anastomosis plus ileostomy in 1case because of pelvic fibrosis and stenosis of neorectum after radiotherapy, mucosal advancement flap repair with a cellular matrix interposition in 3 rectovaginal fistula cases, incision of sinus via the anus in 1 case. During a median follow-up of 28 months, 14(73.7%) DAF patients were cured.

CONCLUSIONSIt is advisable to be cautious that patients with lower site of tumor and anastomosis, neoadjuvant chemoradiotherapy and preventive stoma are at risk of DAF. DAF is clinically silent and most patients can be cured by effective surgical treatment.