A core needle biopsy is the standard method used to diagnose prostate cancer. A biopsy is a short (~10-15 minute), office-based procedure under local anesthesia in which samples of tissue are removed and then examined under a microscope. The doctor will use a transrectal ultrasound (TRUS) probe for guidance and insert a narrow needle through the wall of your rectum into specific areas of your prostate gland.
Though the procedure sounds painful, it typically causes little discomfort because a special biopsy instrument removes the tissue in a fraction of a second. The doctor will also routinely numb the prostate with a local anesthetic injection.
Prior to biopsy, accurate measurement of the gland size is performed. The volume is calculated by the length, width and height of the prostate.
PROSTATE VOLUME = height × width × length × π
The biopsy needle then removes a cylinder of tissue, usually about 10mm long and 1mm across, that is sent to the laboratory to see if cancer is present. A standard of 12 cores are taken, 6 from each side of the prostate. Each tissue core measures 1mm x 10mm in size, which is very small.
The pathologist (a doctor who specializes in diagnosing disease in tissue samples) will determine if there are cancer cells in your biopsy sample by examining it under the microscope. This analysis usually takes 5 to 7 days. If cancer is present, the pathologist will also assign it a Gleason grade.
Preparation Before Your Prostate Biopsy
Prior to your transrectal prostate biopsy, you will need to do the following:
1) Absolutely no blood thinners, specifically aspirin (or aspirin-like medications such as Motrin, Ibuprofen, etc.), Lovanox, or Coumadin for at least 7-10 days prior to the procedure. Please let us know if you are on one of these medications. If a blood thinner has been taken within 7 days of the procedure, the biopsy will be cancelled and re-scheduled.
2) Take an oral antibiotic 1 day prior to the biopsy and 2 days following the procedure to ensure no infection of the prostate. These will be given to you by the nurse during the clinic visit.
3) Perform a bowel preparation the morning of the procedure with a Fleet enema. This will help evacuate the rectal space.
Post-Prostate Biopsy Expectations
Following the transrectal ultra-sound prostate biopsy, you will be expected to provide a urine sample to assess for blood in the urine and ensure that you will be able to urinate. Some patients experience hematuria (blood in urine) and urinary retention requiring a Foley catheter placement. Your blood pressure will also be taken following the procedure.
The main complications that can arise after the procedure include:
1) Infection: During the procedure, normal bacteria from the rectum is transferred to the prostate. The antibiotics you have taken should help eliminate these organisms. However, there remains a 1 percent possibility that a prostate infection can occur. The symptoms would include a fever, chills and sweating. Prostate pain and urinary symptoms may also be present. If you feel that you are experiencing an infection, please contact our office immediately at (773) 564-5355.
2) Bleeding: Following the TRUS biopsy, bleeding can occur. The incidence of significant bleeding is less than 1 percent. Blood in the stool and urine may be noted for several days after the biopsy. Blood in the semen may also be observed for up to 4 - 6 weeks following the procedure. If you are experiencing significant bleeding, please call our office immediately at (773) 564-5355.
Follow-up Visit After Prostate Biopsy
A week following your biopsy, you will be contacted to discuss the findings of the biopsy. If the biopsy report was negative and no cancer was seen, we will schedule a follow-up visit in 6 months with a repeat PSA blood draw.
Unfortunately, biopsies can occasionally miss detecting cancer. This is known as a "false negative" result. If your doctor still strongly suspects you may have prostate cancer (due to a very high PSA level, for example), or certain pathological findings (atypia and high-grade premalignant cells), a repeat biopsy may be needed to help rule this out. Further, watchful surveillance of your PSA would be recommended.
If the biopsy is positive, your doctor will discuss the findings with you and schedule a clinic appointment to review prostate cancer treatment options and the risks and benefits of these treatments.