Transperineal Prostate Biopsies – Review of Indications, Basic Technique, and Recent Literature

Transperineal prostate biopsies have become increasingly popular over recent years. Previously, the gold standard for the diagnostic work-up of prostate cancer was transrectal ultrasound-guided (TRUS) prostate biopsy. Use of the transperineal approach was limited to patients with a contraindication to TRUS biopsy, such as those with a congenital anomaly or prior surgical history involving the rectum.

Performing a TRUS-guided prostate biopsy is a well-known and common procedure for most urologists, and it can be performed in the outpatient setting. The patient is typically positioned in the left lateral decubitus position with the knees and hips flexed 90 degrees. The procedure can be done entirely under local anesthesia, which is usually administered by injecting lidocaine at the lateral edges of the prostate at the level of the seminal vesicles near the bladder base. The standard biopsy can then be obtained with or without using multiparametric magnetic resonance imaging (mpMRI) to assist in the detection of suspicious prostatic lesions.

In contrast, for a transperineal prostate biopsy, the patient is positioned in the dorsal lithotomy position and at most centers, the procedure is typically done with more involved anesthesia i.e., general anesthesia. Historically, prior to the utilization of ultrasound, transperineal biopsies were done under finger-guidance, however in more recent years, biopsies have been done using TRUS attached to a stepper. Additionally, a template, similar to that used for brachytherapy, also attached to the stepper, can be used to sample the whole prostate systematically. Like TRUS-guided prostate biopsies, transperineal biopsies can utilize MRI for targeted biopsies.

The need for general or spinal anesthesia for transperineal biopsies done in the operating theater has been challenged in several recent studies. In a multicenter retrospective study done by researchers in Norway and Germany led by Eduard Baco, MD, PhD (Oslo University Hospital), they  looked at MRI-TRUS-guided transperineal prostate biopsies done under local anesthesia.¹ They evaluated 377 patients at 2 centers, one each in Oslo and Berlin, and found that overall detection of any and clinically significant prostate cancer was 64% and 52%, respectively, in patients with positive mpMRI (defined as mpMRI results with PI-RADS ≥3). Of note, biopsies in this study were done using the mpMRI-TRUS fusion and the 3D navigation system Trinity Perine (Koelis). The perioperative reported pain level was very low (mean visual analogue scale [VAS] score 2).

The major advantage of the transperineal approach is the ability to detect cancer located in the apical and anterior aspects of the prostate, while reducing the risk for infection.^2,3 Pietro Pepe, MD and colleagues at the Cannizzaro Hospital, Catania, Italy, investigated the detection rate of clinically significant prostate cancer for transperineal versus transrectal mpMRI fusion targeted biopsy.⁴ The patients included in this study were digital rectal examination (DRE) negative and had a rising  prostate-specific antigen (PSA). Between 2015 and 2016, 200 patients underwent mpMRI that was positive for a suspicious lesion in 95 (47.5%) cases. When they compared the transrectal and transperineal biopsy results, the investigators found that clinically significant prostate cancer was diagnosed in in 40 (78.3%) vs 56 (93.3%) cases, respectively. Transrectal fusion biopsy versus transperineal-targeted biopsy resulted in 12 vs 1 missed cancers involving the anterior zone and 8 versus 3 cancers of the peripheral gland. Dr Pepe and his colleagues concluded that mpMRI-TRUS transperineal cognitive targeted biopsy detected more clinically significant prostate cancer of the anterior zone compared with the mpMRI/TRUS transrectal fusion approach (93.3 vs 25%, respectively, P=0.001).

Advances made over recent years in software-based technology incorporating MRI have been shown to increase the diagnostic accuracy of the detection of prostate cancer. The best known study of this is the PROMIS trial.⁵  A recently published study by researchers at Harvard Medical School addressed the remaining question of whether there is an added value to the targeted approach vs the standard template alone, and whether both should be recommended, as for transrectal fusion targeted biopsies.⁶ The study identified 301 men who had undergone office-based transperineal biopsy with software fusion biopsy using the PrecisionPoint Transperineal Access System (Perineologic) at Massachusetts General Hospital between 2019 and 2021. The targeted biopsies were all done by taking 3 samples of the suspicious lesion. All biopsies were done under local anesthesia. The overall cancer detection rate was 74.1% vs 63.5% by standard template versus targeted biopsy, respectively. The detection rate of clinically significant prostate cancer was 52.5% vs 59.7%. In addition, when combined, the detection rate of clinically significant prostate cancer was 62.2%, which was more sensitive than either the standard template or the targeted lesion alone. They concluded, that for patients with a concerning lesion on mpMRI, the optimal way to improve the sensitivity of transperineal biopsy is to utilize both a targeted and standard template.

The risk of infection in TRUS-guided vs transperineal prostate biopsies has been well documented. Infection rates after a TRUS-guided prostate biopsy have been reported to be as high as 7%.⁷ Most are self-limiting, although the rate of sepsis is estimated to be 0.3-3.1%,⁷ with a risk of hospitalization as high as 4%.⁸ Data on transperineal prostate biopsy have shown evidence for sepsis rates close to zero.  A recently published meta-analysis identified no significant difference in infection rates, sepsis, or hospitalization after transperineal biopsy, whether or not patients received antimicrobial prophylaxis.⁹

In conclusion, although the standard of care and more familiar approach to performing a prostate biopsy is to use the TRUS-guided approach, there is growing utilization of the transperineal approach. The transperineal approach has been shown to reduce the risk for infection, and possibly increase sensitivity and accuracy in the detection of clinically significant prostate cancer especially when used alongside MRI-targeted biopsy, and now there are several software-based programs available that incorporate transperineal biopsy with the utilization of MRI. While transrectal-guided biopsies can be performed in the outpatient setting under local anesthesia, and initial use of transperineal biopsies were done in the operating room under general anesthesia, the current trend is to perform transperineal biopsies under local anesthesia in the out-patient setting. Major hurdles that still need to be addressed include the cost, physician education and overcoming the learning curve, and further optimization to identify the most reliable template to identify clinically significant prostate cancer while reducing the morbidity associated with prostate biopsy.

David Ambinder, MD is a urology resident at New York Medical College / Westchester Medical Center. His interests include surgical education, GU oncology and advancements in technology in urology. A significant portion of his research has been focused on litigation in urology.  

References 

1. Jacewicz M, Günzel K, Rud E, et al. Multicenter transperineal MRI-TRUS fusion guided outpatient clinic prostate biopsies under local anesthesia. Urol Oncol. 2021;39(7): 432.e1-432.e7. DOI: 1016/j.urolonc.2020.11.009
2. Chang DT, Challacombe B, Lawrentschuk N. Transperineal biopsy of the prostate—Is this the future? Nat Rev Urol. 2013;10 (12):690-702. DOI: 1038/nrurol.2013.195
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5. Ahmed HU, Bosaily AE, Brown LC, et al; PROMIS study group. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet. 2017;389(10071):815-822. DOI:1016/S0140-6736(16)32401-1
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9. Castellani D, Pirola GM, Law YXT, et al. Infection rate after transperineal prostate biopsy with and without prophylactic antibiotics: results from a systematic review and meta-analysis of comparative studies. J Urol. 2022;207(1):25-34. DOI: 1097/JU.0000000000002251
10. Siddiqui MM, Rais-Bahrami S, Turkbey B, et al. Comparison of MR/ultrasound fusion-guided biopsy with ultrasound-guided biopsy for the diagnosis of prostate cancer. JAMA. 2015;313(4):390-397. DOI: 1001/jama.2014.17942