Ultrasound probe positioning to minimize the risk of recto-urethral fistula during cryosurgical ablation of prostate cancer

Objective To evaluate the ability to increase the distance between the rectal mucosa and prostate, and thus decrease the risk of recto-urethral fistula, and to improve the ability to adequately freeze beyond the prostatic capsule during cryosurgical ablation for prostate cancer. Patients and methods The transrectal ultrasound probe was manipulated to increase the distance from the rectal mucosa to prostate in 28 men scheduled for cryosurgical ablation for localized prostate cancer. Ten patients were treated for local recurrence after previous definitive radiotherapy, and cryosurgery was chosen as the primary treatment for the remainder. Results The mean (range) distance from the rectal mucosa to the prostate when the probe was securely applied to the rectal wall was 2.5 (1-7) mm, and could be extended to 9.6 (7-14) mm before the ultrasonogram quality diminished enough to impede accurate placing of the cryoprobe. The mean distance gained as a margin of error was 7.1 (4-12) mm (P < 0.001). In no patient was it felt that visualization during the freezing cycles was impaired. No recto-urethral fistula was identified. Conclusion The manoeuvres described here allow the surgeon to freeze beyond the prostatic capsule while maintaining a visible distance from rectal wall. The extra distance created by this manoeuvre might reduce the risk of recto-urethral fistula, and potentially improve tumour control in the posterior aspect of the prostate, based on the ability to freeze beyond the capsule to reach lethal temperatures in all prostatic tissue.