Transperineal biopsy technique

Transperineal prostate mapping biopsy (TPMB) is an alternative method to standard transrectal ultrasound guided (TRUS) technique to sample the gland. The TPMB technique uses a grid placed against the perineum and in a sterile fashion takes biopsy specimens at 5 mm intervals using a combination of transverse and sagittal imaging. In contrast to the TRUS method where 12–18 samples are typically taken, with the TPMB upwards of 50 biopsies are done. Because the TPMB takes more samples and takes them throughout the volume of the prostate, the results are substantially different than the TRUS method. On average the TPMB finds 30% more cancers when a TRUS biopsy is negative, upgrades low risk cancers that were initially diagnosed by TRUS, and excludes patients from focal therapy because of high incidence of multifocality. Whereas an increasing incidence of flouroquinolone resistant prostate infection and sepsis is associated with TRUS biopsy, hematuria and retention are more common with TPMB.