Control of pain according to the site of periprostatic nerve block in magnetic resonance imaging/targeted transrectal biopsy of the prostate

Ethics approval

This study was approved by the Institutional Ethics Board (Yonsei University Health System, Seoul, Korea, 3-2019-0418), and all procedures were conducted in accordance with the ethical standards of the 1964 Declaration of Helsinki and of its subsequent amendments. The informed consent requirement was waived by the Yonsei University Health System Ethics Committee because this study was based on retrospective, anonymized patient data and did not involve patient intervention or use human tissue samples.

Patient selection

We prospectively collected data from 229 consecutive patients who underwent MRI-targeted transrectal biopsy between January 2019 and September 2020. Patients who were unable to receive transrectal ultrasound probe injection, had severe hemorrhoids (Grade ≥ III, n = 2), had undergone related surgery (n = 2), and unable to communicate (n = 4) were excluded. According to the prebiopsy history, there were no patients with neurological disease such as paraplegia or hemiplegia, and no patients with chronic pain who were taking analgesics routinely. Finally, 221 (96.5%) patients were selected for analysis (Fig. 2).

Figure 2

Study cohort flowchart. MRI magnetic resonance image, GNP periprostatic nerve block, TRUS transrectal ultrasound.

Data gathering

Patient data related to age, PSA level, prostate volume, history of prostate biopsy, Prostate Imaging-Reporting and Data System (PI-RADS) scores, pathology findings, time required for PNB and biopsies, adverse events (vasovagal syncope, allergic reaction, acute urinary retention, urinary retention due to blood clot, and fever), VAS pain scores (0 as no pain to 10 as worse pain) were collected.

Indication of pre-biopsy prostate MRI and prostate biopsy

The indications for prebiopsy MRI to be eligible for the national reimbursement policy included an elevated PSA level, the presence of hypoechoic lesions on the TRUS and/or the presence of a palpable nodule on digital rectal examination or a PSA > 100, 0ng/ml. Need for prostate biopsy was determined by MRI findings, elevated PSA level (>3.0 ng/ml), PSA density, presence of a palpable nodule on digital rectal examination and/or continued increase in PSA level during follow-up.

MRI protocol and analysis

MRI was performed using a 3.0 Tesla system (Intera Achieva 3.0 T, Phillips Medical System, Best, The Netherlands) equipped with a phased array coil (six channels). The MRI protocol involved diffusion-weighted imaging and T2-weighted imaging. The T2-weighted turbo spin-echo MRI was acquired in three planes (axial, sagittal and coronal). MRI datasets were obtained for identical slice locations, with 3 mm slice thickness and no intersection gaps. Two b-values ​​(0–1400) were used and diffusion restriction was quantified via mapping of apparent diffusion coefficients. A dynamic MRI with contrast injection was also performed. All prostate MRIs were evaluated by an experienced radiologist-urologist and classified according to PI-RADS version 2.124. Patients with PI-RADS scores of 3 to 5 were included.

Local anesthesia methods

All patients were asked to lie in the left lateral decubitus position during the procedure. All biopsies were performed by an experienced urologist. After rectal preparation of povidone iodine, 10 cc of 2% lidocaine gel was applied intrarectally (Instillagel®, Farco-Farma GmbH, Cologne, Germany). After 5 min, a transrectal probe was inserted, prostate volume was measured, and PNB was performed with a Chiba needle (A&A MD Inc., Seongnam, Korea).

The site of local anesthesia (base PNB vs base and apex PNB) was determined as follows: (1) Odd days: patients in the PNB base group received PNB on both sides of the base of the prostate and 2.5 cc of normal saline on both sides of the top of the prostate; (2) Even days: Patients in the PNB base and apex group received PNB on both sides of the base of the prostate as well as the apex of the prostate. Injections from the base of the prostate were aimed at the major neurovascular bundle after confirming the echogenic triangular “Mount Everest sign” between the base of the prostate and the seminal vesicle on the parasagittal longitudinal view of the TRUS25. Prostate apex injections targeted a smaller triangular echogenic area between the puborectalis muscles and the apex of the prostate. Each PNB was made using 2.5 cc of 2% lidocaine.9. Patients in all groups received base injections before apex injections.

Simultaneous prostate biopsy techniques

We regularly check urinalysis and urine culture before biopsy decision making. If there is pyuria or a positive urine culture, sufficient antibiotics are used before the biopsy, and the biopsy is done after the follow-up urinalysis and negative confirmation of the urine culture. All patients in this study received oral third-generation cephalosporin as a prophylactic antibiotic for 2 days after biopsy.

All biopsies were performed using the BK 3000 ultrasound system (Analogic Corporation, Peabody, MA, USA) with a 7.5 to 12 MHz multiplanar probe, in the following order: CBx, FBx and SBx. First, CBx was performed with two core biopsies per target. After performing CBx, FBx was performed using the MRI/TRUS fusion system (BioJet; GeoScan, Lakewood Ranch, FL, USA) with two biopsies per target. Therefore, four core biopsies per target were obtained. After performing CBx and FBx, SBx was performed in the order of Right Lateral Base, Right Lateral Mid, Right Lateral Apex, Right Medial Base, Right Medial Mid, Right Medial Apex , left lateral base, left lateral mid, left lateral apex, left medial base, left medial mid, and left medial apex. VAS scores were assessed at different time points: probe insertion, prostate base injection, prostate apex injection, CBx, FBx, SBx, and 15 min after prostate biopsy. We checked VAS scores for all injections and punctures. All biopsies were performed using guide channels, which were 19° to the axis of the sidefire probe transducer (Analogic Corporation, Peabody, MA, USA), and a biopsy instrument 18G disposable core, 20cm (Max-Core®, CR Bard Inc., Covington, GA, USA).

Study endpoints

The primary endpoint was VAS score for each biopsy site and PNB method. Secondary endpoints were differences in pain intensity between biopsy methods and between anterior and posterior sites according to CBx and FBx.

statistical analyzes

VAS scores for base and apex injection were defined as the mean VAS scores for right and left sides in base and apex injections. VAS scores during CBx, FBx, and SBx were defined as the mean VAS scores during individual core biopsies for the three types of biopsies.

Continuous variables are expressed as mean ± standard deviation or median (interquartile range). Categorical variables are reported in number and frequency. The GNP base and GNP base and apex groups were compared using the independent t-test for continuous variables and the chi-square test (Fisher’s exact test) for two or more variables. The results are presented using a linear mixed model and a mean profile plot. The structure of the linear mixed model correlation matrix that showed the relationship between data collected at different times was calculated by applying compound symmetry. Statistical analyzes were performed using SAS (version 9.4; SAS Institute, Cary, NC, USA). Statistical significance was set at p

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