Objective: To evaluate the clinical efficacy of a phased Chinese herbal sitz bath for the treatment of complex anal fistula based on the traditional Chinese medicine theory of "Fuzheng Quxie."

Methods: We enrolled 200 patients with complex anal fistula who were hospitalized and treated surgically in the Department of Anorectal Medicine of Suining Central Hospital from June 2021 to December 2022. The patients were randomly divided into 2 groups of 100 patients each: sitz bath group 1 (postoperation, the patients used a sitz bath with a self-formulated decoction of "Qingre Zaoshi Zhitong" formula, once in the morning and once in the evening) and sitz bath group 2 (postoperation, the patients used the same decoction as the sitz bath group 1, and when the incision began to heal, the patients then used a sitz bath with a self-formulated decoction of "Yiqi Fuzheng" formula, once in the morning and once in the evening). Both groups were treated for 6 weeks. The assessments included wound symptom score, incision healing time, clinical efficacy after treatment, and serum-related growth factor concentrations and anorectal dynamics indicators before and after treatment.

Results: After treatment, sitz bath group 2 had less wound pain, edema, exudate, and granulation growth scores than sitz bath group 1 (P < .05). Postoperative incision healing time was faster in sitz bath group 2 22.96 (1.96) d than in sitz bath group 1 26.19 (2.62) d (t = 9.872, P < .001). The total effective rate after treatment was higher in sitz bath group 2 96% (96/100) than in sitz bath group 1 88% (88/100) (χ2 = 4.4, P = .04). Serum transforming growth factor β, epidermal growth factor, and basic fibroblast growth factor concentrations were higher in both groups after treatment than before treatment, and the concentrations of the growth factors after treatment were higher for sitz bath group 2 than for sitz bath group 1 (P < .001). Anal rest pressure and anal maximum contraction pressure were higher in both groups after treatment than before treatment, and the pressures after treatment were higher for sitz bath group 2 than for sitz bath group 1 (P < .05).

Conclusion: Based on the theory of Fuzheng Quxie, the effectiveness and superiority of a phased Chinese herbal sitz bath for the treatment of complex anal fistula were remarkable, which could promote the improvement of wound symptoms and anal function. This may be related to increases in growth factor concentrations and anorectal dynamics indicators.