Risk factors for infection and acute urinary retention following transperineal prostate biopsy

To calculate the frequency of infection and acute urinary retention (AUR) following transperineal (TP) prostate biopsy at a single high-volume academic institution and determine risk factors for developing these post-biopsy conditions.

Men undergoing TP prostate biopsy from 2012 to 2022 at our institution were retrospectively identified and chart reviewed. TP biopsies were performed with TR ultrasound (TRUS) guidance with anesthesia using a brachytherapy grid template. TRUS volumes were recorded during the procedure, and magnetic resonance imaging (MRI) volumes were calculated using the ellipsoid formula. When available, MRI volume was used for all analysis, and when absent, TRUS volume was used. AUR was defined as requiring urinary catheter placement within 72 h post-biopsy for inability to urinate. Univariable analysis was performed and variables with p < 0.1 and/or established clinical relevance were included in a backward binary logistic regression to produce an optimized model that fit the data without collinearity between variables.

A total of 767 TP biopsies were completed in the study window. The frequency of infection was 1.83% (N = 14/767). The total frequency of AUR was 5.48% (N = 42/767). On multivariable regression, patients who went into AUR were five times as likely to develop infection (p = 0.020). Patients with infection post-TP biopsy were four times as likely to develop AUR (p = 0.047) and with prostates > 61.21 cc were three times as likely (p = 0.019).

According to our model, AUR is the greatest risk factor for infection post-TP biopsy. With regard to AUR risks, infection post-biopsy and prostate size > 61.21 cc are the greatest risk factors.