A biopsy of the prostate gland is usually required when there is a suspicion of prostate cancer. It involves taking multiple small samples of prostate tissue using a biopsy needle, which are then assessed microscopically by a pathologist. The prostate biopsy has traditionally been performed via the rectum (transrectal ultrasound-guided – TRUS – biopsy), because the prostate sits directly in front of the rectal wall and is therefore easily accessible via this route.
Whilst TRUS biopsy remains one of the standard approaches for an initial prostate biopsy, it has potential drawbacks. In some cases, the front part of the gland may not be accessible to biopsy via the rectum. Although prostate cancer arises less commonly in this region, it could be missed by a TRUS biopsy.
Secondly, the TRUS biopsy has a small but significant risk of serious infection, where bacteria may enter the bloodstream (septicaemia). This is due to passage of the biopsy needle through the rectal wall, which cannot be sterilised, into the prostate, which has a rich blood supply. Septicaemia is a serious illness that requires hospital re-admission for intravenous antibiotics and supportive care.
In men, the perineum is the part of the body between the scrotum and anus. A transperineal biopsy of the prostate, performed under a general anaesthetic, is therefore carried out via the skin overlying this area. Excellent imaging is obtained by an ultrasound probe passed into the rectum. Biopsy needles are passed parallel to the long axis of the prostate, allowing access to all aspects of the gland. This approach has the potential for improved sampling, particularly in men who have had a previous negative TRUS biopsy but whose PSA continues to rise. It may also be appropriate for men who are on an active surveillance program for previously-diagnosed low risk prostate cancer.
The transperineal biopsy has the additional potential advantage of a much lower risk of infection, as the skin of the perineum can be easily disinfected by routine surgical preparation immediately prior to the procedure.
A higher number of tissue samples are usually taken by transperineal biopsy. Also, some of the samples are taken from areas closer to the urethra, which runs through the prostate. As a result, there appears to be a higher risk of temporary voiding difficulty, including urinary retention. Fortunately, this may last only a day or two, and is easy to treat.
Urologists at AUA are experts in transperineal biopsy of the prostate and published an award-winning paper on their own results showing a rate of zero serious infection when using this technique. As a result of their clinical research, AUA urologists offer the transperineal approach to the vast majority of their patients who require prostate biopsy.