Abstract: Objective To explore the clinical value of platelet-rich plasma （PRP） combined with transanal opening of intersphincteric space （TROPIS） modified thread drawing method in the treatment of complex anal fistula. Methods A total of 90 cases of complex anal fistula admitted from September 2023 to September 2025 were included in the study. The patients were divided into two groups using a random number table method, with 45 cases in each group. The control group received TROPIS modified thread drawing, and the study group received PRP local injection therapy additionally. Wound healing indicators （wound healing time, wound exudation at postoperative 7 d and 14 d）, anal function （Wexner incontinence score at postoperative 1 month and 3 months）, and clinical efficacy （overall effectiveness and recurrence rate） were compared between the two groups. Results Compared with the control group, the study group had faster wound healing, less exudation at postoperative 7 d and 14 d, lower Wexner incontinence score at postoperative 1 month and 3 months （better anal function）, increased cure rate, and decreased recurrence rate （P<0.05）. Conclusion PRP combined with TROPIS modified thread drawing can accelerate wound closure, reduce secretions, maintain anal function, and reduce the risk of recurrence, with promising prospects for promotion.

Key words: Platelet-rich plasma, TROPIS modified thread drawing method, Complex anal fistula, Wound healing, Anal function, Clinical efficacy