The definitive diagnosis of prostate cancer requires a prostate biopsy to obtain tissue for histopathologic confirmation. Prostate biopsy is an invasive procedure and is thus associated with pain. Different techniques of anaesthesia for prostate biopsy have been described and applied. However, opinions still vary regarding the optimal method of pain control. Local anaesthesia appears to be a simple, inexpensive and safe method of anaesthesia for prostate biopsy, and it was adopted in this study.
The demographic variables of the two groups in this study were essentially similar; the mean age for the intra-rectal lidocaine gel and the peri-prostatic nerve block groups was 68.1 years and 65.4 years, respectively. This finding is similar to the mean age in other studies that compared the two local anaesthetic techniques [13, 17]. The median prostate-specific antigen and prostate volume were 18.6 ng/ml and 55.2 g, respectively, and were also not significantly different between both groups. These values were higher than those reported in the study by Rodriguez et al., though large average prostate volume was reported by Hetta et al. in a North African population [13, 18].
This study is unique in the sense that it is one of the few studies that evaluated the tolerability of anaesthetic administration. Understandably, the mean pain score during anaesthetic administration was significantly lower in the intra-rectal lidocaine gel group than that in the peri-prostatic nerve block group (1.6 versus 3.7). This is because pain inevitably accompanies tissue infiltration of local anaesthetic compared to topical instillation of intra-rectal anaesthetic gel, in which other than the mild discomfort associated with dilatation of the anal verge at the insertion of the nozzle, it induces relatively little or no pain. However, Turgut et al. reported that about one-third of patients had pain during peri-prostatic nerve block with 72.9% of them having pain scores of less than 4 and no patient having pain score above 6 . Unlike this study, basal peri-prostatic nerve block was used and it was not compared with another anaesthetic technique. In this study, a high pain score above 6 was recorded in 5 (9.4%) of the patients in the peri-prostatic nerve block group. This could be related to the inadvertent stimulation of the rich sensory nerve fibres in the anal mucosa during needle introduction for the apical peri-prostatic nerve block [20, 21].
When we looked at the anaesthetic effect of intra-rectal lidocaine gel, it was sub-optimal while peri-prostatic nerve block provided superior pain relief during prostate biopsy with mean pain scores of 6.8 versus 2.9, respectively. Hetta et al. recorded a mean pain score of 6.4 versus 3.0 in the intra-rectal lidocaine gel and peri-prostatic nerve block groups, respectively, which is in agreement with this study . However, Trucchi et al. in their study to determine whether local anaesthesia reduces pain in trans-rectal prostate biopsy reported a much lower mean pain score of 5.5 and 0.5 in the intra-rectal lidocaine gel and peri-prostatic nerve block arm of the study, respectively . In contrast to this study, they used carbocaine as the local anaesthetic agent. Carbocaine causes less vasodilatation and less absorption and has a longer duration of action and may thus be more effective than the lidocaine used in our study. Demir et al. reported a higher mean pain score of 8.2 in the intra-rectal lidocaine gel arm of their study which compared three different anaesthetic techniques for prostate biopsy . However, the patients were not randomized into groups in their study.
Further evidence in support of the superiority of peri-prostatic nerve block in comparison to intra-rectal lidocaine gel, is the study of Rodriguez et al. and Alavi et al. that compared the efficacy of both local anaesthetic techniques [13, 17]. The binding of lidocaine gel to the rectal mucosa might be responsible for its lower efficacy for prostate biopsy. On the other hand, the direct infiltration of the peri-prostatic nerves may have facilitated the superior pain relief provided by the technique.
The superiority of peri-prostatic nerve block over intra-rectal lidocaine gel is also supported by the observation that 45.3% of patients who had intra-rectal lidocaine gel were satisfied compared to the statistically significant higher proportion of patients, 86.8%, that were satisfied with a peri-prostatic nerve block. Naidoo et al. while comparing both methods of anaesthesia reported that 7.8% versus 2.4% of the patients had poor tolerance of prostate biopsy in the intra-rectal lidocaine gel and the peri-prostatic nerve block groups, respectively . However, patients’ tolerance of the procedure was assessed by six different operators unlike in this study where individual patients reported their satisfaction with the biopsy procedure.
Findings in this study which showed a significantly lower proportion of patients willing to accept a repeat biopsy if necessary in the intra-rectal lidocaine gel group (60.4%) compared to the proportion in the peri-prostatic nerve block group (88.7%) are similar to the observation of Tobias-Machado et al. who reported an acceptance rate for repeat biopsy of 60.0% for the intra-rectal lidocaine gel group . However, a higher rate of acceptance of repeat biopsy (98.3%) was recorded in the peri-prostatic nerve block arm of their study in comparison to the findings in this study. In contrast to this study, an acceptance rate of 87.0% versus 95.7% in the intra-rectal lidocaine gel and peri-prostatic nerve block groups has been reported by Naidoo et al. which was not significantly different between both groups . However, the reported mean pain scores in that study, 3.1 versus 2.0 in the intra-rectal lidocaine gel and peri-prostatic nerve block groups, respectively, were much lower than those reported in this study. The significantly higher satisfaction rate and acceptance of repeat biopsy in the peri-prostatic nerve block group further reinforce the objective benefit of achieving a significantly lower pain score in this group.
Bleeding, infections and voiding complications were recorded following prostate biopsy in the present study. Although the rate of rectal bleeding reported in this study (48.1%) was close to that reported by Ugwumba et al. (40.2%), the rate of occurrence of fever was higher in the present study (22.6% versus 8.9%) . This could be because their patients had antibiotic administration for 3 days after the biopsy which may have resulted in the lower rate of infection. The rate of haematuria (39.6%) and acute urinary retention (1.3%) were, however, within the range reported by Loeb et al. in a systematic review of prostate biopsy complications .
The limitation of this study was the fact that pain assessment was done at the end of the biopsy procedure rather than for each core of tissue taken during the procedure. It was also not feasible to blind the clinician performing the procedure to the technique of anaesthesia used. However, this would not affect the outcome of this study as the procedures were carried out in line with the study protocol and assessment of outcome measures was done by a blinded research assistant using objective measures.