SAN DIEGO -- The pain of a prostate biopsy may not be fully numbed by local anesthesia, according to Mayo Clinic researchers who determined that the procedure may never be free of all discomfort.
SAN DIEGO, Sept. 14 -- The pain of a prostate biopsy may not be fully numbed by local anesthesia, researchers reported here. To top it off, the instillation of the anesthesia hurt, too.
In a report on the pain and discomfort of the office-based biopsies, Mayo Clinic researchers said that men undergoing the procedure said that installation of lidocaine to numb the gland was more painful than insertion of the transrectal ultrasound probe.
What's more, biopsies performed near the apex of the prostate hurt more than those performed in other zones, reported Richard A. Ashley, M.D., and colleagues in Rochester, Minn., at a meeting of the American Urological Association's North Central chapter.
"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," said 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," he said.
Under the direction of Michael L. Blute, M.D., chairman of urology at Mayo, Dr. Ashley and colleagues took an objective look at the subjective topic of pain during 12-core prostate biopsies.
They looked at 243 men who were scheduled for office prostate biopsies because of abnormal findings on digital rectal exam or transrectal ultrasound. The men all had elevated levels of prostate specific antigen, no prior history of pain syndromes, infection, or ano-rectal disorder, and were not taking any medications for chronic pain.
In the single-blinded study, the men were randomly assigned to receive injections in one of three areas:
The anesthetic protocol was installation of 20% benzocaine jelly for five minutes, followed by 1% lidocaine for two minutes.
The procedure was performed with a side-firing ultrasound probe and biopsy gun, with two sections taken from the base, two in the midsection, and two in the apex of the peripheral zone of each prostatic lobe.
The main study outcome was score on the Visual Analog Scale of pain, in which patients are asked to rate pain from 0 (none) to 10 (worst imaginable).
Pain scores were collected at the ultrasound probe insertion, lidocaine installation, each firing of the biopsy gun, and after the procedure.
Based on the mean VAS score, the investigators determined that the probe insertion was the least agonizing part of the procedure, followed in ascending order by pain at the end of the procedure, base biopsy, mid biopsy, apical biopsy, and topped off by lidocaine installation.
They also found that standard block was the least effective, and that the apical block, although producing the most pain during the injection of lidocaine, provided the best overall protection from pain.
The investigators also found that overall the biopsy procedure was well tolerated, with more than 84% of VAS score being lower than 5.
"The prostate biopsy likely will never be a completely painless procedure, but it should be tolerable," Dr. Ashley said. "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 informed that pain may be greater in some areas of the prostate during a biopsy than others, and the pain may not be completely blocked by anesthetic, he added.