Abstract: Objective To compare the efficacy of bidirectional isobaric drainage and low incision and high thread-drawing in the treatment of complex anal fistula. Methods From January 2019 to December 2022, 70 patients with complex anal fistula treated in Yuyang District Hospital of Yulin City were selected as the research object,according to the different treatment methods of patients, they were divided into experimental group and conventional group, with 35 patients in each group. The experimental group adopted bidirectional isobaric drainage treatment, the conventional group adopted low incision and high hanging line treatment.The treatment effect, wound healing time, anal pain, 1 d, 3 d, 7 d, and anal function, 5 d, 1 and 3 month were compared between the two groups. Results There was no significant difference between the experimental group and the routine group (P>0.05). The length of postoperative hospital stay and wound healing in the experimental group were shorter than those in the routine group, and the difference was statistically significant (P<0.05). On the 1st, 3rd and 7th day after operation, the VAS scores of patients in the two groups decreased gradually, and the scores in the experimental group were lower than those in the routine group, with statistical significance (P<0.05). On 5th postoperative day, the scores of Wexner in both groups increased, and gradually decreased in January and March after operation. Compared between groups, the scores in the experimental group were lower than those in the routine group on 5th postoperative day, January and March, and the difference was statistically significant(P<0.05). Conclusion Bi-directional isobaric drainage is as effective as low incision and high thread-drawing in the treatment of complex anal fistula, but it causes lower pain and faster healing time, and can effectively protect the function of anal sphincter and prevent anal incontinence.

Key words: bidirectional isobaric drainage, low cut and high thread hanging, complex anal fistula, wexner