Pelvic plexus block to provide better anesthesia in transperineal template-guided prostate biopsy: a randomised controlled trial

Early screening for prostate cancer (PCa) can significantly lower disease-related morbidity and even prolong life expectancy [1]. Transperineal template-guided prostate biopsy (TTPB) is one of most effective procedures for detection of prostate cancer [2, 3]. However, compared with the transrectal biopsy, transperineal route may cause more pain [4]. In the absence of anesthesia, about 20% of patients refused to undergo prostate biopsy [5]. Therefore, effective anesthesia is a important precondition for successful prostate biopsy [6]. Periprostatic nerve block (PNB) has attracted more and more attention due to its excellent analgesic effect and high safety. At present, PNB is regarded as the “golden standard” of analgesia during prostate biopsy [7‐10]. In 1996, Nash et al. [11] were the first to introduce PNB, and found that it can relieve the pain during transrectal ultrasound (TRUS) -guided prostate biopsy. Conde et al. [12] found that the anesthesia effect of PNB was superior to oral morphine. Hergan et al. [13] conducted a meta analysis of fourteen trials and found that PNB had better anesthesia effect than that of local anesthesia or placebo. However, some patients have poor response to PNB in clinical practice. Apart from sensitivity to pain, most of these patients were with larger prostate volume [14]. It may be that, due to the increase in prostate volume may lead to a decrease in prostate cancer detection rate [15]. Hence, in order to improve the positive rate, it is necessary to increase the number of needles, which aggravates the pain of patients. Kevar et al. [16] called the condition as “cumulative pain”. Besides, the irregular growth of prostate cancer [17] increases the difficulty of locating the angle prostate-bladder-seminal vesicle. In addition, Nguyen et al. [18] found that apical biopsies were more painful than were biopsies from other areas of the prostate under PNB.

Hence, PNB cannot completely eliminate discomfort. A small number of nerve fibers are located on the anterior and superolateral parts of the prostate, and PNB does not block these nerve fibers, which is the limitation of PNB. Recently, some studies have shown that direct blocking of the origin of the prostatic nerves, the pelvic plexus, may obtained better analgesia [19‐22].

In this study, we compared pelvic plexus block (PPB) with conventional PNB to evaluate whether PPB has better anesthetic efficacy in the process of TTPB.

From July 2016 to August 2017, 271 patients were performed TTPB in Clinical Medical College of Yangzhou University. Of these, 21 patients did not fulfil inclusion criteria and 5 did not provide consent. Ultimately, 245 patients were randomized into three groups. Groups-1, 2 and 3 included 81, 83 and 81 patients, respectively (Fig. 3). The age, prostate volume, serum PSA level and the number of cores showed no significant differences among these three groups, as presented in Table 1.

In groups-1, 2 and 3, VAS-1 was 3.3 ± 1.6, 2.7 ± 1.3 and 2.1 ± 1.1, and VNS-1 was 2.8 ± 0.9, 3.1 ± 0.8 and 3.3 ± 0.2, respectively. The pain scores in group-3 were significantly lower than in group-2 (P = 0.003). Both the group-2 and group-3 outperformed the group-1 in alleviating pain. Satisfaction scores in group-3 were significantly higher than in group-2 (P = 0.039). Group-2 and group-3 were higher than group-1 in terms of satisfaction. In groups-1, 2 and 3, VAS-2 was 0.7 ± 0.4, 0.6 ± 0.5 and 0.5 ± 0.3, and VNS-2 was 3.5 ± 0.6, 3.5 ± 0.6 and 3.7 ± 0.8, respectively. At 30 min after the procedure, there were no statistically significant differences in VAS scores or VNS scores among the three groups (Table 2).

There was no significant difference in complications including hematospermia, hematuria, infection and urinary retention among the three groups (Table 3).

TTPB has become one of the most commonly methods for the diagnosis of Pca. As an invasive operation, TTPB is related to obvious discomfort and pain.

Currently, PNB is safe, easily performed and high-efficiency, and it is generally regarded as the preferred method for analgesia during biopsy needles inserting into the prostatic tissue [7‐10]. Recently, PPB was reported to have a definitive theoretical advantage for decreasing pain, challenging conventional PNB [19‐22].

The nerves of the prostate come from the pelvic plexus, including the sympathetic and parasympathetic nerves. The sympathetic nerve fibers are mainly transmitted to the pelvic plexus through the superior hypogastric plexus. Parasympathetic fibers originate from the 2–4 sacral spinal nerves and are transmitted through them. These nerves unite to form the pelvic plexus [21, 25]. And which is rectangular and 4 to 5 cm in length. The midpoint of pelvic plexus is located on the lateral to the apex of bilateral seminal vesicles. The pelvic plexus is penetrated by many vessels that supply the the prostate, seminal vesicles, bladder and rectum. At the most caudal portion of the pelvic plexus, the nerve innervating the prostate and the cavernosal nerves, the prostatic plexus, is generated [26, 27]. Subsequently, the prostatic plexus and the vessels of the prostate form the NVB, which is distributed along the posterolateral margin of the prostate and is considered to be the primary nerves innervating the prostate. However, there are a few other nerve fibers also running on the anterior and superolateral surfaces of the prostate [11, 19, 27, 28].

PNB mainly blocks the prostatic plexus located on the posterolateral side of the prostate, which is the primary nerve that supplies the prostate [19‐22]. However, a small number of nerve fibers located on the anterior and superolateral parts of the prostate were omitted and thus not blocked. This may be the reason why a research has found that biopsies at the apex of the prostate were more painful than those at other sites [18]. PPB directly injects lidocaine into the pelvic plexus, and all nerve fibers supplying to the prostate are blocked. Hence, compared with PNB, PPB have theoretical advantages.

Wu et al. [22] first reported PPB. Under grayscale ultrasound guidance, they injected 5 ml of 1% lidocaine into lateral to the seminal vesicles apex. However, they didn’t find any reduce the pain associated with biopsy. Conversely, Akpinar et al. [21] found that compared with PNB, the analgesic efficacy of PPB (2 ml 2% lidocaine for each pelvic plexus) was better. Cantiello et al. [19] mixed 1% lidocaine with 0.75% Naropin and injected 2.5 ml mixture into each pelvic plexus lateral to the apex of the seminal vesicles under the guidance of color Doppler ultrasound. Jindal et al. [20] injected 2.5 ml 2% lidocaine into the bilateral pelvic plexus. In studies of Cantiello et al. and Jindal et al., they reported PPB had a better anesthetic effect than did PNB. The results of the last three researches are different from those of Wu et al., and the reason may be related to the use of color Doppler ultrasound, which can provide more accurate positioning of pelvic plexus.

All of the above studies were meant to explore the anesthetic efficacy of PPB in the transrectal prostate biopsy. Owing to the high positive rate and few complications, The value of TTPB in the diagnosis of Pca is becoming more and more important [2, 3]. Hence, we evaluated the anesthetic efficacy of PPB in TTPB in this study. Our present outcomes showed that the PPB group had higher satisfaction and lower pain scores than did the PNB group. Both these groups had higher levels of satisfaction, and pain control was better than that in the group without any nerve block. After 30 min of the biopsy, most patients returned to normal without pain. There were no differences in pain scores or satisfaction scores at 30 min after the procedure among the three groups.

Doppler ultrasound can avoid damage to the vessels and accurately inject the local anesthetics into the region of the pelvic plexus, thus reducing the incidence of complications related to the nerve block anesthesia technique, especially vascular complications. In our study, there was no significant difference in complications including hematospermia, hematuria, infection and urinary retention among the three groups .

Our study has several limitations. We assessed pain scores and satisfaction scores after biopsy. This might lead to ‘recall bias’. Nevertheless, we chose this method for avoiding any possible factors for disturbing biopsy performed by the resident, which may affect the scores. Although VAS and VNS are relatively objective indicators of pain detection, the evaluation of pain is still dominated by the subjective feelings of patients, and there is a lack of objective quantitative indicators, which needs further study. And in the future, we would study whether PPB results in more adhesions, making the surgical steps more difficult. We also need to explore whether it affects erectile function and urinary continence.

Under the guidance of color Doppler ultrasound, PPB has better analgesic efficacy than did PNB in TTPB process and both were superior to no nerve block.