The appropriate length of the needles to be used and the number of planes to be treated are calculated based on the ultrasound transverse (latero-lateral) diameter measurement of the prostate and the cystoscopic prostate urethreal length, respectively. The length of the needle deployed in millimeters is calculated using the formula L = (transverse width divided by 2)-6. In practice, tissue ablation extends to 3mm distal to the needle tips toward the lateral prostatic capsule; the tips are placed at a minimum of 6mm from the prostatic capsule to avoid thermal ablation effects to it.
To conduct the procedure, the patient is placed in the lithotomy position and the catheter inserted transurethrally into the prostate urethra up to the bladder neck. The number of treatment planes is calculated based on the length of the prostatic urethra.
1 Data derived from the Prostiva RF Therapy System Guide