Researchers at Mayo Clinic have evaluated the major sources of pain for some men during in-office prostate biopsy and an anesthetic method that can best lessen it. Findings were presented recently at the annual meeting of the North Central Section of the American Urological Association in San Diego.
Most prostate biopsies are performed on men who have abnormal digital rectal exams or abnormally elevated prostate-specific antigen (PSA) tests to evaluate the potential presence of cancer.
"Prostate biopsy evokes significant anxiety for some men due to anticipated pain associated with the procedure," says Richard Ashley, M.D., Mayo Clinic urology resident and lead study investigator. "We also noted that it seemed more men had pain with their prostate biopsies than we would have liked, and we wanted to make this procedure as comfortable as possible."
The researchers found about 16 percent of men who undergo prostate biopsy experienced a moderate or higher level of pain -- pain scores of 5 or more on a scale from 1 to 10. The injection of lidocaine to dull pain during the biopsy caused more pain than the insertion of the transrectal ultrasound probe, a small probe about the size of a cigar inserted into the rectum to produce images of the prostate gland during the biopsy. They also discovered that taking tissue samples in certain locations tested in a prostate biopsy were more likely to cause pain. Specifically, biopsy of the part of the prostate closest to the urethra, the prostate apex, was more painful than biopsy of the part closest to the bladder, the prostate base.
"We found we cannot predict who will have higher levels of pain at the time of a prostate biopsy simply based on the patient's history and features," says Dr. Ashley. "We discovered the location of biopsy was the most predictive of higher pain scores -- not age, body mass index, family history, presence of cancer, inflammation, whether a lump was palpable, or whether the prostate was large or small."
The investigators also found that anesthesia administered by direct infiltration of the prostate apex and the surrounding rectal tissues may provide better pain control during a prostate biopsy than other anesthetic methods.
"The prostate biopsy likely will never be a completely painless procedure, but it should be tolerable," says Dr. Ashley. "Patients should request that anesthetic be used at the time of a biopsy, and pain control should be the standard of care in a urologist's office. It does not take much time, and patients do benefit from this simple procedure to make the biopsy more tolerable. Patients should also be aware that different prostate locations biopsied are associated with more pain, and this may never be completely overcome by anesthetic. However, a complete and thorough sampling of the prostate gland is necessary to give the most accurate diagnosis to the patient."
In the study, Dr. Ashley and colleagues recruited 243 men scheduled to undergo in-office prostate biopsy in the Department of Urology at Mayo Clinic. The researchers randomly assigned the men to three different types of anesthetic: injection between the prostate base and seminal vesicle where the neurovascular bundle lies; intraprostatic injection into the substance of the gland, from the base to the apex; and injection at the prostate apex and surrounding rectal wall tissue. The biopsies were performed using a side-fire ultrasound probe and a biopsy gun. Six biopsies were performed on the right and left side of the prostate of each patient, focusing on the peripheral zone where most cancers occur.
The findings in this study need to be verified by other researchers in a larger study, according to Dr. Ashley.
Other study investigators include: Jonathan Routh, M.D.; Amy Krambeck, M.D.; Sameer Siddiqui, M.D.; Jeffrey Slezak; Lance Mynderse, M.D.; Michael Blute, M.D.; and Matthew Gettman, M.D.
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