TRUS Biopsy: The Human Pincushion

It wasn’t so long ago when the standard transrectal ultrasound-guided (TRUS) biopsy involved only six needles. It was called a sextant biopsy based on the Latin word sextans, meaning “a sixth.” As time would prove, it missed more than 40% of prostate tumors because it was essentially blind and random. To correct the problem, the number of needles rose to 10, then 12. Many urologists preferred to take 14 samples, and a “saturation” TRUS biopsy consisted of 20-24 needles. With all the variance, the walnut-sized prostate gland essentially became the human equivalent of a pincushion.

Since prostate tumors can’t be seen with ultrasound, it makes sense that the way to improve the odds of capturing prostate cancer is to increase the number of needles. However, doing so also raises the probability of biopsy-related side effects such as infection, prostatitis (inflammation), erectile dysfunction, urinary bleeding and rectal bleeding. A recent study reported one research team’s efforts to find the “optimum” number of needles that would maximize cancer detection while keeping risks to a minimum.[i]  The study involved 180 patients whose elevated PSA and/or abnormal digital rectal exam (DRE) were suspicious for prostate cancer. They were randomly assigned to one of three groups: Group A had sextant biopsies, Group B and 12-core biopsies, and Group C had 18-core biopsies. The team compared the rates of cancer detection and post-biopsy infection/prostatitis among the 3 groups:

Cancer detection Infection/prostatitis
6 cores 13.3% 28.3%
12 cores 35% 38.3%
18 cores 40% 58.3%


The authors concluded, “The best balance between detection rate of prostate cancer and infectious complications of biopsies achieved in twelve-core biopsy protocol. Twelve-core biopsy enhances the rate of prostate cancer detection with minimum adverse effects.” My gut reaction is OUCH!

At our Center, we offer in-bore MRI-guided targeted biopsy instead of TRUS biopsy. Real time MRI guidance has unquestionable superiority over TRUS biopsy. Using a minimal number of needles, detection rates are at least 60%[ii]. Because of the reduced number of needles, infection/prostatitis risks are very low. MRI guidance ensures that the nerve bundles that control erection are not compromised by the biopsy needles, and we can avoid hitting the urethra. The prostate gland is not a pincushion, but living tissue with an important purpose. We make every effort to take the best possible care of that tissue, just as we respect and care for the whole person.

[i] Ghafoori M, Velayati M, Aliyari Ghasabeh M et al. Prostate Biopsy Using Transrectal Ultrasonography; The Optimal Number of Cores Regarding Cancer Detection Rate and Complications. Iran J Radiol. 2015 Apr 22;12(2):e13257. doi: 10.5812/iranjradiol.13257.

[ii] Arsov C, Rabenalt R, Blondin D, Quentin M et al. Prospective Randomized Trial Comparing Magnetic Resonance Imaging (MRI)-guided In-bore Biopsy to MRI-ultrasound Fusion and Transrectal Ultrasound-guided Prostate Biopsy in Patients with Prior Negative Biopsies. Eur Urol. 2015 Oct;68(4):713-20.