A Novel Perineal Nerve Block Approach for Transperineal Prostate Biopsy: An Anatomical Analysis-based Randomized Single-blind Controlled Trial

Abstract

Objective: To develop and validate a novel perineal nerve block approach for transperineal prostate biopsy.

Patients and methods: Five adult male cadavers were dissected to delineate the superficial and deep branches of the perineal nerve. Afterwards, 90 out of 115 patients were selected and randomly assigned to receive periprostatic, periapical triangle, or branches of perineal nerve (BPN) block. The primary outcome was the maximal pain intensity associated with transperineal prostate biopsy, which was assessed by the 10-point visual analog scale. The secondary outcomes included the number of biopsy with visual analog scale of ≥4 in each biopsy procedure, and the incidences of complications.

Results: On the horizontal line of the upper anal border, the locations of the superficial branch of perineal nerve on the left and right sides were 1.87 ± 0.05 cm and 1.86 ± 0.06 cm, respectively; and the deep branch were 2.15 ± 0.07 cm and 2.16 ± 0.06 cm, respectively, from the midline, and lied between the deep layer of superficial fascia and prostate capsule. The number of cases finally enrolled in data analysis in periprostatic block, periapical triangle block, and BPN block groups were 26, 27, and 30, respectively. The maximal pain intensities were 3.4 (3.1-3.7), 3.3 (3.0-3.6), and 1.8 (1.5-2.2) in the 3 groups, respectively, and the numbers of biopsy with the pain intensity of ≥4 were 4.0 (3.2-4.9), 4.2 (3.3-5.2), and 0.7 (0.1-1.2), respectively. There were 4, 3 and 4 cases developing hematuria, and 1, 1 and 2 burdened with urine retention after biopsy in the 3 groups, respectively.

Conclusion: Collectively, BPN block is a safe, effective and repeatable local anesthesia approach for transperineal prostate biopsy.