EP516 - Platelet-Rich Plasma in Fistula-in-Ano: A Modest Adjunct in Complex Disease

Purpose/Background: Fistulae-in-ano remain difficult to treat, with available approaches often achieving only modest and inconsistent results. Obtaining durable healing while preserving sphincter function remains a significant challenge. Platelet-rich plasma (PRP), a blood product with a high concentration of growth factors and cytokines, has been proposed as an injection to promote tract closure without sphincter damage. This study details an institutional experience using PRP as an adjunct or standalone therapy for complex, previously treated fistulae-in-ano.

Methods/Interventions: All adults with refractory or recurrent fistula-in-ano treated with PRP between January and May 2024 at a tertiary referral center were retrospectively reviewed. Fistulas arising from anastomotic leaks were excluded. Demographics, comorbidities (diabetes, Crohn's disease with systemic therapy), prior interventions, and detailed tract anatomy from operative and MRI reports were collected from the electronic medical record. Operative details, number of PRP injections, associated procedures, and subsequent interventions were also recorded. Each procedure included tract debridement and injection of 5 mL of autologous PRP, performed alone or combined with another technique (radially emitting laser diode closure, fistulotomy, over-the-scope clip [OTSC], or fistula plug). The primary outcome was complete healing, defined as an asymptomatic patient with no residual tract on examination. Secondary outcomes included time to healing and change in tract diameter. Univariate analysis compared the healed and non-healed groups, and a cumulative hazard curve estimated time to healing.

Results/Outcomes: Forty patients were included (63% male; median age 46 years (interquartile range [IQR] 38-59) and a median body mass index of 29 (IQR 27-35). Four patients (10%) had Crohn's disease (all on systemic therapy), and four (10%) had diabetes. Median follow-up after the first PRP was 10 months [IQR 5-15]. PRP was performed in combination with another procedure in 34 patients (85%) and alone in 6 patients (15%). Concurrent procedures included a fistulotomy (44%), laser diode assisted closure (33%), fistula plug (21%), or OTSC (16%). Fourteen patients (35%) achieved healing after a median of three PRP injections [IQR 1-3], with a mean time to healing of 9 months (95% confidence interval, 6.6-11.3) (Figure 1). Five patients (36%) required additional interventions before complete healing, including fistulotomy (n = 1), laser diode assisted closure (n = 1), chronic wound debridement (n = 2), or blood patch (n = 1). Posterior tracts were most common (63%) and healed in 36%, followed by anterior (30%, 42% healed) and anorectovaginal (8%, 0% healed) (p = 0.39). Among non-healed patients with paired measurements (n = 17), final tract diameter was smaller than baseline (median 5 vs 6 mm; p = 0.03). There were no complications associated with PRP injections. Clinical and anatomical characteristics are summarized in Table 1.

Conclusion/Discussion: In this cohort of complex, previously treated fistulas, PRP was safe and technically feasible but achieved only modest healing rates and frequently required additional interventions. Its benefits appeared limited, and durable healing was uncommon in chronic or multiply operated tracts. These findings suggest PRP may serve only a supportive role within multimodal management of fistulae-in-ano.

Figure 1. Cumulative Incidence of Fistula Healing Over Time in Patients Treated with Platelet-rich Plasma
Table 1. Clinical Characteristics and Fistula Anatomy of Patients Treated with Platelet-Rich Plasma for Fistula-in-Ano According to Healing Status