Subcutaneous local anaesthetic after transperineal prostate biopsy under general anaesthesia: a randomised trial.

Abstract

To determine whether subcutaneous local anaesthesia (LA) infiltration at perineal puncture sites reduces immediate postoperative pain after transperineal (TP) prostate biopsy performed under general anaesthesia (GA). In this two-centre, patient-blinded, randomised, placebo-controlled trial, men undergoing TP prostate biopsy under GA (GATP biopsy) were allocated 1:1 to receive either 20 mL 0.5% bupivacaine or 20 mL normal saline, infiltrated subcutaneously into the perineal skin at the conclusion of biopsy. The primary endpoint was the proportion of patients reporting moderate-to-severe pain (visual analogue scale [VAS] score > 3) 30 min postoperatively. Secondary endpoints included the Short-Form McGill Pain Questionnaire (SF-MPQ) and opioid use in recovery. Of 150 men randomised, 140 were included in the modified intention-to-treat analysis. Moderate-to-severe pain occurred in 22.5% of controls and 8.7% of patients receiving LA (absolute risk reduction 13.8%, 95% confidence interval 2.1-25.6; P = 0.035; number needed to treat = 7). The median VAS and SF-MPQ scores were 0 in both groups. Opioid administration did not differ significantly (10% control vs 19% LA; P = 0.15). In an exploratory post hoc subgroup, the benefit of LA infiltration was greater among men undergoing >20-core biopsy (34.1% vs 10.6%). No significant complications occurred. Subcutaneous LA infiltration significantly reduces immediate moderate-to-severe pain following GATP biopsy. Although overall pain scores were low, a clinically meaningful subset benefitted from this simple, low-cost, and safe intervention. These findings also have relevance to contemporary TP prostate biopsy under LA workflows, supporting the concept that superficial infiltration may provide additive value alongside established block-based analgesic protocols.