Evaluation of major sources of pain during prostate biopsy and the finding that pain appears to correlate most closely with sampling location within the gland should lead to better local anesthesia, according to a presentation at the annual meeting of the North Central Section of the American Urological Association.

“Prostate biopsy evokes significant anxiety for some men due to anticipated pain associated with the procedure,” said Richard Ashley, MD, Mayo Clinic physician 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.”

In the study, 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, the location of the neurovascular bundle; 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.

Biopsies were performed using a side-fire ultrasound probe and 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 malignant tumors are found.

The researchers found about 16 percent of men who underwent prostate biopsy experienced a moderate to high level of pain -- pain scores of 5 or more on a scale from 1 to 10. Injection of lidocaine during the biopsy caused more pain than insertion of the transrectal ultrasound probe.

Investigators also found that taking tissue samples in certain locations 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,” said 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 surrounding rectal tissues may provide better pain control than other anesthetic methods. Ashley concluded that the findings need to be verified by other researchers in a larger study before they can be fully implemented as practice guidelines.