What does TRUS mean?
A biopsy of the prostate is performed using Transrectal ultrasound (TRUS) which uses sound waves to create an image of the prostate on a video screen. The ultrasound probe is placed in the rectum. The computer image generated by the sound waves echoing from tissue allows the urologist to note the size (gland volume) and shape of the prostate gland and whether any abnormalities exist. The most common of which are shadows which might signify the presence of prostate cancer but not all prostate cancers are visible.
How is the biopsy performed?
Biopsies are usually carried out under ultrasound guidance using a spring-loaded biopsy device coupled to the transrectal probe, also known as a prostate biopsy gun. A biopsy usually consists of 12-14 samples (cores) which are carefully removed from the various segments on both sides of the prostate. The cores are labeled and placed in containers for microscopic examination by a pathologist in order to make a precise diagnosis of the patient's condition.
For a full biopsy discussion, see a UCSF Patient guide: Transrectal Ultrasound Guided Prostate Biopsy
What is a saturation (or mapping) biopsy?
A saturation biopsy utilizes a template to accurately map the prostate and remove many cores (typically 30-80) from all sections of the prostate. A saturation biopsy is normally performed in a hospital setting under anesthesia. The number of cores is determined by the size of the prostate. It may be suggested for a patient who has had one or more negative biopsies and whose PSA is consistently rising or prior biopsies had questionable results. It may also be suggested when the original biopsy found only a small incidence of cancer and focal therapy is being considered. A saturation biopsy may be considered investigational by your insurance company and may not covered without proof of medical necessity.
Should you have a biopsy?
The decision to biopsy is complex and should be pursued if the available evidence suggests a significant probability of prostate cancer. It is usually based on an elevated (or rising) PSA or on the results of a Digital Rectal Exam but there are many other factors to consider. To understand these factors and the biopsy procedure, please see our March 2011 article Eleven Decisions Before Prostate Biopsy.
Prostate cancer can only be diagnosed based on microscopic examination of biopsy samples or of material removed as part of a TURP (transurethral resection of the prostate) performed to reduce benign growth of the prostate.
What are the risks of biopsy?
You can expect some pain related to the procedure. Be sure to ask about what anesthesia will be used, especially if you have a low tolerance to pain.
You may experience light bleeding from the rectum, which should resolve in a day or two. You should expect to see blood in your semen and rust-colored urine which may last for a few weeks. Be sure to ask about discontinuing medicines and supplements that thin the blood before having the procedure.
With any invasive procedure, there is a risk of infection. Be sure to ask about bowel preparation and antibiotics.
See: Infection Associated With Prostate Biopsies PDF
While it is possible for cancer cells to be spread by a biopsy, it is considered to be a very low risk. About 500,000 biopsies are performed each year in the USA and there are only a couple of cases documenting spread reported in the medical literature.
What is the meaning of your gland volume?
The gland volume is the size of the prostate calculated based on the image on the ultrasound display. It is usually given in cubic centimeters (cc). It is used to calculate PSA Density and to evaluate the use of treatments like brachytherapy and cryotherapy. Sometimes, the prostate size is given in grams. This value is roughly equivalent to cc.
What if your biopsy is positive for cancer?
The pathology report will provide you valuable information regarding the location, volume and aggressiveness of your prostate cancer. You should review it carefully with your physicians. See Understanding Your Diagnosis for a full discussion of its meaning.
What if your biopsy is negative for cancer?
The pathology report of the biopsy cores will determine if you have prostate cancer. It can also provide considerable information that can be used to evaluate whether a repeat biopsy will find cancer. These include the findings of high-grade PIN, atypical cells or evidence of inflammation. If your biopsy has these findings, you may want to consider having the slides reviewed by a Pathologist who is an expert for prostate cancer. Those cells may in fact be cancer. Also, further tests may be performed on the samples. Patients with at least 1 alpha-methylacyl-coA racemase positive high grade PIN gland were 5.2 times more likely to have a subsequent diagnosis of prostate cancer on repeat biopsy than those without any alpha-methylacyl-coA racemase positive high grade PIN glands.
The decision regarding a repeat biopsy follows the same process as the original biopsy.
After one or more negative biopsies, if the PSA continues to rise, you might consider a targeted biopsy using color Doppler ultrasound. See the Diagnostic Imaging section under Understanding Your Diagnosis.
1– Stewart J et al. Prognostic significance of alpha-methylacyl-coA racemase among men with high grade prostatic intraepithelial neoplasia in prostate biopsies. J Urology 2008 May;179(5):1751-5
Page updated 9/6/11