[Application value of gracilis muscle flap in repairing urethral perineal fistula after Miles operation].

Objective: To investigate the clinical effect of transposition of gracilis muscle flap in repairing urethral perineal fistula after Miles operation.

Methods: The clinical data of 3 patients with urethral perineal fistula treated in the Second Affiliated Hospital of Zhejiang University from September 2023 to November 2024 were analyzed retrospectively. All patients were male, aged from 59 to 68 years (mean 63 years). All patients underwent Miles operation because of low rectal cancer. Urethral perineal fistula occurred after 2 months to 13 years of the operation. The underlying comorbidities included diabetes (2/3), preoperative chemoradiotherapy (1/3), and chemotherapy alone (1/3). The endourethral fistula was located in the apical and membranous part of the prostate, with a diameter of 1.5-2.0 cm and a mean of 1.7 cm. Suprapubic cystostomy was performed one month before operation. In all 3 cases, perineal inverted "Y" incision was taken under general anesthesia to expose urethral fistula, cut off necrotic tissue and suture urethral fistula. The gracilis muscle of the right thigh was taken and turned through the perineal subcutaneous tunnel. and 6 stitches were suture at the urethral fistula.

Results: The operations of all 3 patients were completed successfully. The follow-up period ranged from 2 months to 12 months, with an average of 8 months. There was no case of urinary incontinence after removal of catheter 3 weeks after operation. In two patients, urethrography was reviewed 1 month after surgery to show no fistula residue and urethral stenosis, and the fistula was removed. In one patient with a history of radiotherapy, urethrography was reviewed 1 month after surgery to show a small amount of contrast overflow around the urethra, and urethrography was reviewed again 3 months after surgery to show no contrast overflow around the urethra. All the 3 patients had no disturbance of movement of the right lower limb, and the pain of different degrees of thigh incision was acceptable and basically relieved half a month after operation.

Conclusion: Gracilis muscle flap is one of the effective methods for repairing urethral perineal fistula after Miles operation，which has a precise surgical result and few complications.