Transurethral resection of the prostate (TURP) is a commonly performed surgery in the elderly male population. Neither regional anaesthesia nor general anaesthesia is able to provide any significant postoperative analgesia of extended duration after TURP procedures due to pain resulting from the prostatic capsule, bladder spasm and catheter-related discomfort.1
The innervation of the prostate gland is primarily due to the pelvic plexus, but neuroanatomical studies have demonstrated that the afferent fibres of the bladder can travel with the pudendal nerve.2 Ultrasonography-guided pudendal block with a transgluteal approach is recommended in the prone position.3 However, because the TURP procedure is performed in the lithotomy position, transperineal pudendal block may be a more practical approach.4
This study aims to describe ultrasonography-guided transperineal pudendal block in TURP patients in the lithotomy position and investigate the effects of this approach on postoperative analgesia, catheter-related discomfort and patient satisfaction.
Ethical approval for this study (Ethical Committee, 2011/86) was provided by the Ethical Committee Erciyes University Hospital, Kayseri, Turkey (Chairperson Prof Dr Kader Köse) on 01 November 2011.
To test the proposed procedure for ultrasonography-guided transperineal pudendal block in the lithotomy position, the technique was performed on two fresh cadavers. A Sonosite M turbo ultrasound machine (Bothell, Washington, USA) with a curved array transducer (HFL 38x/13-6 MHz Transducer) was used to perform the pudendal block. When the ischial tuberosity was palpated, the ultrasonography transducer was placed obliquely on the ischial tuberosity. After observing the hyperechogenity of the ischial tuberosity, the transducer was moved in the medial direction to observe the sacrotuberous ligament, which is less echogenic than bone. A total of 8 ml of 0.9% normal saline was injected over the area where the sacrotuberous ligament and ischial tuerosity was combined. Distribution of saline to the area was observed concurrently. The needle used to perform the block was left in place and dissected to observe the nearby pudendal artery and the pudendal nerve.
Written informed consent was obtained from the patients. This randomised, double-blinded, controlled study included 40 patients with an age of 50 to 75 years who were classified as American Society of Anesthesiologists (ASA) I to III and undergoing TURP for benign prostate hypertrophy. The study was registered at ClinicalTrials.gov (NCT01501279). The patients were randomly allocated to two groups according to a random, computer-generated table (Group C, control; Group P, pudendal nerve block).
Anaesthesia induction was achieved using 2.5 mg kg−1 of intravenous (i.v.) propofol and 1 μg kg−1 of fentanyl, a classic laryngeal mask airway (LMA) was placed. Anaesthesia was maintained using 50% nitrous oxide in oxygen and desflurane. At the junction of the sacrotuberous ligament and the ischial tuberosity, the pudendal artery was viewed via colour flow Doppler. A 22G 100 mm Echoplex peripheral block needle (Vygon, France) was subsequently advanced just medial to the artery by using an in-plane technique (i.e. 5 cm deep to the skin, as detected in the two cadavers). The localisation of the pudendal nerve was confirmed by ipsilateral anal sphincter contraction induced using a 0.5 to 0.6 mA Plexygon nerve stimulator at 1 Hz (Vygon, Italia), and 8 ml of 0.25% bupivacaine was injected. The same procedure was applied to the other side. After the block was placed, the operation began. When the operation was complete, a 20-F urinary catheter was inserted, and the balloon was inflated with 40 ml saline. Intermittent bladder irrigation was applied for 24 h. Postoperative analgesia was maintained using a 20 mg PCA i.v. bolus of tramadol with a 10-min lockout period (CADD-Legacy PCA pump) (Smiths Medical, St. Paul, Minnesota, USA).
Catheter-related discomfort was recorded as severe (i.e. behavioural responses, such as flailing, attempts to pull out the catheter or strong vocal responses), moderate (i.e. reported by the patient without behavioural responses) and mild (i.e. discomfort in the suprapubic region that was reported by the patient only after questioning).5 Pain and catheter-related discomfort were assessed postoperatively after 10 min, 1, 4, 8, 12 and 24 h using the visual analogue scale (VAS) scale (‘0’ to indicate no pain to ‘10’ to indicate maximum pain). After 24 h, patient satisfaction was assessed using a 10-point satisfaction score (i.e. 0, not satisfied; 10, fully satisfied). The patients were questioned in the PACU and postoperatively by an anaesthesiologist who was not aware of the study groups. Statistical analysis was performed using SPSS 15.0 software (SPSS Inc., Chicago, Illinois, USA), t-test for continuous variables, the Mann–Whitney U test for nonparametric variables and χ2 and Fisher's exact test for categorical variables.
The incidence of catheter-related discomfort and the VAS scores were higher in the control group than in the pudendal block group (P < 0.05). Total tramadol consumption was 213.5 ± 44.5 mg in the control group and 103.8 ± 26.8 mg in the pudendal block group (P < 0.001). Patient satisfaction scores were 3.1 ± 0.6 in the control group and 9.1 ± 1.4 in the block group (P = 0.001) (Table 1). Three patients in the pudendal block group complained of penile and scrotal numbness that improved spontaneously within 6 h. There were no complications related to the block, such as intravascular injection or haematoma.
Previous studies indicated that the major causes of postoperative pain in TURP patients were bladder discomfort, catheter-related discomfort and interventions to the prostatic capsule.1 The cause of catheter-related discomfort is the contraction of the bladder, which is caused by irritation.6 These contractions are caused by parasympathetic nerve activity mediated by muscarinic receptors.6 Afferent fibres carrying pain sensation from the base of the bladder, the urethral sphincter and the prostatic capsul also travel via the pudendal nerve. Yoo et al.7 reported that efferent somatic nerve branches originating from the pudendal nerve can also cause bladder contractions. Thus pudendal nerve block could not only reduce reflex bladder irritability but also reduce pain perception. We conducted our study in patients undergoing TURP because we believed that in this type of surgery, pudendal nerve block would help to reduce pain due to catheter related discomfort and routine bladder irrigation. We have demonstrated the efficacy of pudendal block in preventing severe pain caused by bladder spasm and catheter-related discomfort.
In conclusion, the administration of a pudendal nerve block to patients undergoing TURP provides effective postoperative analgesia and reduces catheter-related discomfort and postoperative analgesic demand.
Acknowledgements relating to this article
Assistance with the study: none.
Financial support and sponsorship: none.
Conflicts of interest: none.
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