Ultrasound-guided Pudendal Nerve Block Research Articles

Analgesic efficacy of Ultrasound-Guided Caudal Block versus Pudendal Nerve Block in BRAKA - I Repair for Paediatric Hypospadias

Objective: To compare the efficacy of ultrasound-guided caudal versus pudendal nerve block analgesia in paediatric patients undergoing hypospadias. Study Design: Quasi-experimental study. Place and Duration of Study: Combined Military Hospital Rawalpindi, Pakistan from Mar to Sep 2022. Methodology: Paediatric patients with ages ranging from 4-12 years with ASA Grade I/II planned for hypospadias repair were included. Sixty-eight patients were divided into Group-C (caudal block) and Group-P (pudendal nerve block), after randomization. Group-C patients received ultrasound-guided caudal block while pudendal nerve blockade was performed under ultrasound guidance in Group- P. Demographic variables, requirement of rescue analgesics, CHEOPS scoring at 0, 1, 2,6 and 12 hours, and complications in the intraoperative period were recorded. Results: Pain scores at the 6th and 12th hour were significantly reduced in Group-P compared to Group-C. Requirement of analgesia was lesser in Group P 01(2.9%) compared to 11(32.3%) in Group C with a p-value of 0.006. Out of 34 patients in Group-C 07(20.6%), patients encountered complications compared to Group-P, which had no complications. Conclusion: Ultrasound-guided pudendal nerve block is superior to caudal block in providing adequate perioperative analgesia with fewer complications and decreased requirement of additional analgesic supplements.

Efficacy and safety of different nerve block methods for the treatment of pudendal neuralgia

Objective: To identify efficacy and safety of pudendal nerve block in tubing through the third posterior sacral foramen for the treatment of pudendal neuralgia (PN). Methods: A retrospective study with 222 PN patients was conducted in the Department of Pain Management of Beijing Tsinghua Changgung Hospital from January 2020 to April 2023. These patients were divided into two groups based on their treatment methods: pudendal nerve block in tubing through the third posterior sacral foramen (observation group, n=101) and ultrasound-guided pudendal nerve block (control group, n=121). Primary outcome measure was the 90-day postoperative pain relief rate. Secondary outcome measures included visual analog scale (VAS) at 1, 7, 14, 30 and 90 d after surgery, the incidence of tramadol uses after surgery, postoperative self-rating anxiety scale (SAS) scores and the incidence of adverse events. Factors that influenced pain relief within 90 days after surgery were analyzed by using binary logistic regression analysis. Results: Observation group included 34 males and 67 females, aged (49.8±16.0) years old. Control group included 38 males and 83 females, aged (43.7±14.0) years old. The 90-day postoperative pain relief rate of the observation group patients was 38.6% (39/101), which was higher than the 24.0% (29/121) of the control group patients (P=0.018). Both the observation group and the control group showed an interaction effect of time and group after treatment for VAS scores (both P<0.05). In intra-group comparison, the VAS scores at 1, 7, 14, 30 and 90 d after treatment in both groups were lower than those before treatment (all P<0.05). In inter-group comparison, the differences of the VAS scores were not statistically significant in the observation group compared with those in the control group at 1, 7, 14, 30 and 90 d after surgery (all P>0.05). The SAS score of the observation group at 90 d after surgery was 51.5±6.2, which was lower than the 53.4±5.8 of the control group (P=0.022). There was no statistically significant difference in the incidence of postoperative tramadol uses and adverse events between the two groups (both P>0.05). Pudendal nerve block in tubing through the third posterior sacral foramen was a protective factor for pain postoperative relief in PN patients at 90 d after surgery (OR=1.92, 95%CI: 1.05-3.48, P=0.033). Conclusion: Pudendal nerve block in tubing through the third posterior sacral foramen is a safe and effective minimally invasive treatment. It has a higher postoperative pain relief rate within 90 d after surgery, without increasing the uses of postoperative rescue analgesics and the incidence of adverse events.

Application of ALCOCK Tube Ultrasound-guided Internal Pudendal Nerve Block in Postoperative Anal Analgesia

Background: While surgery is the most effective treatment for anorectal diseases, traditional anesthesia methods are increasingly regarded not suitable for the clinical needs of anorectal patients. Although pudendal nerve block can play a good analgesic role in the anal region, the traditional pudendal nerve block is performed under blind probing, which is inaccurate in positioning, has poor anesthesia effect, and causes many complications. Objectives: At present, ultrasound-guided pudendal nerve block for analgesia has emerged in clinical practice. Therefore, the present study aimed to investigate the analgesic effect of ALCOCK tube ultrasound-guided internal pudendal nerve block in anal surgery. Methods: A prospective study was conducted. A total of 134 patients who underwent anal surgery in Hangzhou Lin'an District First People's Hospital from May, 2021 to July, 2022 were divided into three categories according to mixed hemorrhoids, anal fistula, and anal fissure and randomly divided into control and experimental groups. The two groups were treated with corresponding surgical treatment, and the experimental group was treated with bilateral pudendal nerve block under the guidance of ALCOCK tube ultrasound at the end of the operation. The operation time, blood loss, initial postoperative pain time, and visual analogue scale, postoperative pain score at each time point, incidence of complications, and patient satisfaction were recorded and analyzed. Results: The operation time of the experimental group was significantly longer than that of the control group, the bleeding volume of anal fistula in the experimental group was more than the control group, the first pain time of anal fistula in the experimental group was higher than that of the control group. The first pain score of anal fistula in the experimental group was lower than that of the control group. Follow-up showed that the pain scores of anal fistula and anal fissure groups were inconsistent 48 h after surgery. The total incidence of adverse reactions was lower, and the patient satisfaction was higher in the experimental group than in the control group. Conclusion: The application of internal pudendal nerve block under the guidance of ALCOCK tube ultrasound in anal surgery has a good analgesic effect and high patient satisfaction, which is worthy of promotion.

Randomized controlled trial (RCT) comparing ultrasound-guided pudendal nerve block with ultrasound-guided penile nerve block for analgesia during pediatric circumcision

IntroductionOptimal analgesia for circumcision is still debated. The dorsal penile nerve block has been shown to be superior to topical and caudal analgesia. Recently, the ultrasound-guided pudendal nerve block (group...

Ultrasound-Guided Pudendal Nerve Block versus Ultrasound-Guided Dorsal Penile Nerve Block for Pediatric Distal Hypospadias Surgery

Introduction: The primary aim of the study was to use the duration until the first postoperative analgesic requirement after two different block techniques to compare the analgesic effect. The secondary aims were to compare the two methods for postoperative Children’s Hospital Eastern Ontario Pain Scale (CHEOPS) scores, complications, and parental satisfaction level. Materials and Methods: This prospective, observational study was conducted with male patients aged 1–7 years in the ASA I–II group, who were scheduled for hypospadias surgery between November 2019 and April 2020. Ultrasound (US)-guided pudendal nerve block (PNB) or US-guided dorsal penile nerve block (DPNB) was administered under general anesthesia before the operation. Postoperative analgesic need, postoperative pain, complications, and parental satisfaction were noted. The STROBE checklist was followed for reporting. Results: The study was conducted with 30 patients in total, divided into 15 patients receiving PNB and 15 patients receiving DPNB. The effective minimum block duration was longer in the pudendal group at 22.22 ± 0.61 h than in the DPNB group at 22.19 ± 0.57 h. Additional analgesic was required in 4 subjects in the pudendal group and 5 in the DPNB group. There was no statistically significant difference in terms of the variables between the two groups (p > 0.05). Discussion: US-guided DPNB and PNB were shown to provide successful postoperative analgesia and to have similar effectiveness in pediatric patients undergoing hypospadias surgery in this first prospective study of its kind in the literature. Conclusions: US-guided DPNB and PNB have been demonstrated to provide effective, safe, and long-term postoperative analgesia in pediatric patients who have undergone hypospadias surgery. Parental satisfaction in both groups is positively influenced by the minimum postoperative analgesia requirement, the long-term analgesic effect, and the lack of any complications.

Ultrasound Image-Guided Pudendal Nerve Block on Analgesic Effect of Perineotomy under Optimized Fast Super Resolution Reconstructed Convolutional Neural Network Algorithm

This work was aimed to study the analgesic effect of pudendal nerve block on obstetrics and gynecology under the guidance of ultrasound image based on optimized fast super resolution reconstructed convolutional neural network (FSRCNN) algorithm. A total of 110 primiparas from hospital who gave birth through vagina were randomly rolled into experimental group (55 cases) and control group (55 cases). The optimized FSRCNN algorithm was constructed, compared with the FSRCNN algorithm and the Bicubic algorithm and applied to 110 cases of maternal patients undergoing perineotomy under ultrasound image-guided pudendal nerve block. Visual analogue scoring (VAS), incision suture pain VAS score, occurrence of complications, puerpera labor time, and newborn weight were recorded and compared, so did Apgar score of newborns, numbness of maternal thigh, recovery of puncture site, and satisfaction of maternal analgesia. The results showed that the peak signal-to-noise ratio (PSNR) of the high-resolution image reconstructed by the FSRCNN algorithm was 32.68 dB and that reconstructed by the optimized FSRCNN algorithm was 32.19 dB. The PSNR of the Bicubic algorithm processed image was 28.51 dB. In the lateral resection of episiotomy in the second stage of labor, the visual analog score (2.3 ± 1.5 points) of the experimental group was inferior to that of the control group (7.1 ± 2.6 points) ( P &lt; 0.05 ). The visual analogue score of stitch pain (1.3 ± 0.8 points) was also inferior to that of the control group (5.2 ± 1.9 points) ( P &lt; 0.05 ). Moreover, the satisfaction of the parturients in the experimental group (9.86 ± 0.41 points) was considerably superior to that of the control group (7.36 ± 1.25 points) ( P &lt; 0.05 ). In short, the optimized FSRCNN algorithm had a short training time and good reconstruction effect. Ultrasound-guided pudendal nerve block had a substantial analgesic effect on the second stage of labor and improved parturients’ satisfaction.

Comparative study between ultrasound-guided pudendal nerve block and caudal epidural block anesthesia in children undergoing hypospadias surgery

BackgroundThe aim of the study is to compare the effectiveness and safety of ultrasound-guided pudendal nerve block versus caudal epidural block as a part of multimodal analgesia in children undergoing hypospadias surgery.In this prospective, single-blinded study, 50 patients were randomized into 2 groups (25 each group) either receiving ultrasound-guided pudendal nerve block group A or caudal epidural block group B. In the pudendal nerve block group, patients were injected with 0.3 mL/kg 0.25% bupivacaine and 1 ug/kg fentanyl. In the caudal epidural group, patients were injected with 1 mL/kg 0.25% bupivacaine and 1 ug/kg fentanyl. Consumption of paracetamol was assessed during the first 24 h postoperatively. The “objective pain scale” done by Hannalah and Broadman was used to assess postoperative pain.ResultsThis prospective randomized controlled single-blind clinical study was performed on total (50) ASA status I or II patients, of age 3 to 6 years scheduled for hypospadias surgery.For the primary outcome, there was no statistically significant difference found between the two studied groups regarding objective pain score at arrival to PACU with p value = 1.000 while there was a statistically significant increase in pain score in group B than group A at 6 h and 12 h with p value = 0.017 and 0.003, respectively. Also, no statistically significant difference found between the two groups after 18 h with p value = 0.238 may be due to receiving acetaminophen dose in group B. Finally there was a statistically significant increase found in objective pain score in group B at 24 h than group A with p value = 0.015. And there was a statistically significant increase in time to first analgesia in group A than group B with p value < 0.001 while there was a statistically significant increase in total dose of acetaminophen in group B than group A with p value < 0.001.ConclusionBoth ultrasound-guided pudendal block and caudal epidural block are effective and safe methods for postoperative analgesia for children undergoing hypospadias surgery but ultrasound-guided pudendal block gives more postoperative pain control.

Ultrasound-Guided Pudendal Nerve Block Combined with Propofol Deep Sedation versus Spinal Anesthesia for Hemorrhoidectomy: A Prospective Randomized Study.

Background and Objectives. Several anesthesia techniques were applied to hemorrhoidectomy, but postoperative pain and urinary retention were still two unsolved problems. The aim of this prospective randomized study was to evaluate the effect of ultrasound-guided pudendal nerve block (PNB) combined with deep sedation compared to spinal anesthesia for hemorrhoidectomy. Methods. One hundred and twenty patients undergoing Milligan–Morgan hemorrhoidectomy were randomized to receive PNB combined with deep sedation using propofol (Group PNB, n = 60) or spinal anesthesia (Group SA, n = 60). Pain intensity was assessed using the visual analogue scale (0: no pain to 10: worst possible pain). The primary outcome was pain scores recorded at rest at 3, 6, 12, 24, 36, and 48 h and on walking at 12, 24, 36, and 48 h postoperatively. Secondary outcomes were analgesic consumption, side effects, and patient satisfaction after surgery. Results. Ultrasound-guided bilateral PNB combined with deep sedation using propofol could successfully be applied to Milligan–Morgan hemorrhoidectomy. Postoperative pain intensity was significantly lower in Group PNB compared to Group SA at rest at 3, 6, 12, 24, 36, and 48 h (p < 0.001) and during mobilization at 12, 24, 36, and 48 h (p < 0.001) postoperatively. Sufentanil consumption in Group PNB was significantly lower than that in Group SA, during 0–24 h (p < 0.001) and during 24–48 h (p < 0.001) postoperatively. Urinary retention was significantly lower in Group PNB compared to Group SA (6.9% vs 20%, p=0.034). The patients in Group PNB had higher satisfaction compared to Group SA (p < 0.001). Conclusions. Ultrasound-guided PNB combined with propofol sedation is an effective anesthesia technique for Milligan–Morgan hemorrhoidectomy.

A Comparison of the Postoperative Analgesic Effectiveness of Ultrasound-Guided Dorsal Penile Nerve Block and Ultrasound-Guided Pudendal Nerve Block in Circumcision

Aim: The aim of this study was to compare the postoperative analgesic effectiveness of the 2 block types. We also aimed to evaluate the effect of these block types on the postoperative complications and parental satisfaction. Materials and Methods: This prospective observational study was conducted between April and July 2019 at a training and research hospital. Patients aged between 5 and 12 years in the ASA I-II group, who were scheduled for circumcision, were included in the study. The primary outcome was the pain measured using the Children’s Hospital Eastern Ontario Pain Scale and the Faces Pain Scale-Revised. The secondary outcomes were the postoperative complications and parenteral satisfactions. Results: The number of patients receiving a pudendal block (n = 40) and dorsal penile nerve block (DPNB) block (n = 40) was equal. No statistically significant difference was found between the groups that were administered a DPNB and pudendal block in terms of pain scores (p > 0.05). We did not observe any postoperative block-related complications or side effects. Parents reported excellent satisfaction in both groups. Discussion: Ultrasound (US)-guided pudendal nerve block and US-guided DPNB provided effective and long-lasting postoperative analgesia for circumcision surgery. Conclusions: This study has shown that both blocks provide postoperative analgesia with similar effectiveness and ensured a very comfortable period at the circumcision surgery. Clinicians can use either of these techniques depending on their clinical circumstances and experience.

Ultrasound-guided bilateral pudendal nerve blocks of nulliparous women with epidural labour analgesia in the second stage of labour: a randomised, double-blind, controlled trial

ObjectiveTo explore whether an ultrasound-guided pudendal nerve block (PNB) could decrease anaesthetic use, thereby shortening the length of the second stage of labour in women undergoing epidural analgesia.DesignProspective, single-centre, randomised,...

The pudendal nerve block for ambulatory urology: What's old is new again. A quality improvement project

Caudal epidural analgesia (CEA) is a common analgesic technique performed for pediatric penile surgeries; however, it has associated morbidity. The pudendal nerve block (PNB) has been described as an effective analgesic alternative to CEA. In this quality improvement study, we aim to assess the efficacy of PNB as compared to CEA within our ambulatory surgery center (ASC). We demonstrate our initial experience employing PNB for ambulatory pediatric urology procedures. Using retrospective, non-randomized, time-series, observational data, a comparative effectiveness study of CEA and PNB was performed. Patients less than three years old, who underwent circumcision, hypospadias repair, congenital chordee repair, correction of penile angulation/torsion, and buried penis repair with or without scrotoplasty, between January 1, 2015-September 9, 2019 with either CEA or PNB in an ASC at a single institution were included. Standard protocols for local and postoperative analgesia were used. Outcome measures were post anesthesia care unit (PACU) pain scores, morphine rescue rates, and PACU length of stay (LOS). These were analyzed using statistical process control (SPC) charts; standard SPC rules were used to detect special cause variation. A total of 999 patients were identified; 746 (74.7%), 172 (17.2%) and 81 (8.1%) received CEA, ultrasound guided PNB (US-PNB) and landmark directed PNB (LD-PNB), respectively. Demographic data was comparable between the three cohorts. There was no special cause variation in the outcome measures between the CEA, US-PNB and LD-PNB cohorts for maximum pain score, morphine rescue rates and PACU LOS. Pain outcomes and PACU LOS were similar between the CEA, US-PNB and LD-PNB cohorts, suggesting equivalent postoperative pain control between these techniques within our cohort. Previous published data has reported lower postoperative pain scores with PNB as compared to CEA for patients undergoing circumcision and hypospadias repair. PNB is non-inferior to CEA for analgesia for pediatric penile surgery, with LD-PNB being as effective as US-PNB. Given the simplicity and documented lower risk profile, PNB may be preferred to CEA for ambulatory pediatric urology procedures.

Ultrasound-guided pudendal nerve block in patients undergoing open hemorrhoidectomy: a double-blind randomized controlled trial.

In this double-blind randomized trial, we aimed to compare the postoperative pain, complications, and length of hospital stay in patients undergoing open hemorrhoidectomy under spinal anesthesia with or without the pudendal nerve block. Patients undergoing Milligan-Morgan hemorrhoidectomy under spinal anesthesia were randomized to undergo a pudendal nerve block or no intervention. Postoperative pain on the visual analogue scale (VAS) at 6, 12, 24, and 48 h; opioid administration; and length of hospital stay were recorded and analyzed. Over the study period, 49 patients were included and 23 randomized in the treatment arm. No differences in terms of age, gender, and preoperative risk factors were noted between groups. The pain on the VAS at 6, 12, 24, and 48 h was 2.8 vs. 4.6 (p = 0.046), 3.4 vs. 4.7 (p = 0.697), 1.4 vs. 3.1 (p = 0.016), and 1.0 vs. 2.1 (p = 0.288) in the treatment and control groups respectively. No differences in opioids use or complications were noted. Length of hospital stay was 1.2 vs. 1.8 days respectively (p = 0.046). No complications directly associated to the pudendal nerve block were observed. Multivariate analysis revealed that the pudendal nerve block was an independent factor reducing the postoperative pain. The ultrasound-guided pudendal nerve block in patients undergoing open hemorrhoidectomy under spinal anesthesia showed a statistically significant reduction in postoperative pain and length of hospital stay. The proposed technique appeared to be safe and feasible and may be recommendable in patients undergoing open hemorrhoidectomy. ClinicalTrials.gov Identifier: NCT04251884.

Accuracy of Ultrasound-Guided Pudendal Nerve Block in the Ischial Spine and Alcock’s Canal Levels: A Cadaveric Study

Blockade of the pudendal nerve (PN) using ultrasound (US) guidance has been described at the levels of the ischial spine and Alcock's canal. However, no study has been conducted to compare anatomical accuracy between different approaches in targeting the PN. To investigate the accuracy of US-guided injection of the PN at the ischial spine and Alcock's canal levels. This study also compared the accuracy of the infiltrations by three sonographers with different levels of experience. Eight Thiel-embalmed cadavers (16 hemipelvises). Three physiatrists trained in musculoskeletal US imaging with 12 years, five years, and one year of experience performed the injections. Each injected a 0.1-mL bolus of colored dye in both hemipelvises of each cadaver at the ischial spine and Alcock's canal levels under US guidance. Each cadaver received three injections per hemipelvis. The accuracy of the injection was determined following hemipelvis dissection by an anatomist. The injections were accurate 33 times out of the total 42 attempts, resulting in 78% accuracy. Sixteen out of 21 injections at the ischial spine level were on target (76% accuracy), while the approach at Alcock's canal level yielded 17 successful injections (81% accuracy). The difference between the approaches was not statistically significant. There was also no significant difference in accuracy between the operators. US-guided injection of the PN can be performed accurately at both the ischial spine and Alcock's canal levels. The difference between the approaches was not statistically significant.

Randomized trial comparing the incidence of unintended sciatic nerve block following ultrasound-guided pudendal nerve block with two different volumes of ropivacaine for hemorrhoidectomy: A pilot study

Aim: To compare the incidence of unintended sciatic nerve block following pudendal nerve block in the interligamentous plane with two different volumes of ropivacaine for post hemorrhoidectomy pain. Materials and Methods: 30 patients undergoing hemorrhoidectomy were enrolled for the study and randomly divided into two groups. Prior to the block a scout scan was performed and the pudendal artery, nerve and the sciatic nerve were identified in the interligamentous plane. All the patients received bilateral pudendal nerve block under ultrasound guidance with 5ml of 0.25% ropivacaine in group 1 and 10 ml in group 2. The spread of local anaesthetic to the ipsilateral sciatic nerve was noted under ultrasound imaging. The time of first rescue analgesia (FRA) and total analgesic requirement(TAR) were noted in both groups. The overall patient satisfaction was assessed with a three point scale.The unintended motor and sensory block of the sciatic nerve was noted. Results: The right pudendal artery was visualized in all cases where but left pudendal artery was not visualized in 1 case. The right & left pudendal nerve was visualized in 40% & 46.7% of cases in group I and 40% in both sides of group 2. The incidence of spread of drug towards the right and left sciatic nerve was more in group II (73.3% & 66.6%) than group I (40% & 33.3%). Statistically significant difference was not noted in the time for FRA (P value 0.684) & TAR (P value 0.579). There was no clinically significant sciatic nerve block. Conclusion: We conclude that less volume of local anaesthetic can achieve effective pudendal nerve block minimizing the spread to ipsilateral sciatic nerve.

Ultrasound-guided pudendal nerve block in children: A new technique of ultrasound-guided transperineal approach.

Transperineal pudendal nerve block guided by nerve stimulator is used in pediatric anesthesia as an alternative to caudal analgesia in perineal surgery. The risk of rectal puncture or intravascular injection is inherent to this blinded technique. We described a new technique of transperineal pudendal nerve block, with ultrasound guidance, to improve safety of the technique. The first goal of this study was to describe this new technique and to test its feasibility. The second objective was to evaluate intra operative effectiveness and postoperative pain control. After parental and children consent, this prospective descriptive study included children aged 1-15 years, ASA status I-III, scheduled for general anesthesia associated with bilateral pudendal nerve block for an elective perineal surgery. After standardized general anesthesia, the anesthesiologist performed pudendal nerve block under ultrasound guidance with "out of plane" approach and evaluated the visualization of anatomical structures (ischial tuberosity, rectum, and pudendal artery), of the needle and of the local anesthetic spread. Pudendal nerve block failure was defined as an increase in mean arterial blood pressure or heart rate more than 20% compared to baseline values after surgical incision. In the postoperative period, the need for rescue analgesia was noted. During the study period, 120 blocks were performed in 60 patients, including 59 boys. Quality of the ultrasonographic image was good in 81% of blocks, with easy visualization of ischium and rectum in more than 95% of cases. Localization of the tip of the needle was possible for all pudendal nerve blocks, directly or indirectly. The spread of local anesthetic was seen in 79% of cases. The block was effective in 88% of cases. The new technique of ultrasound-guided pudendal nerve block, described in this study, seems to be easy to perform with a good success rate, and probably improves safety of the puncture and of the injection by real-time visualization of anatomical structures and local anesthetic spread.

Ultrasound-guided Pudendal Block Is a Viable Alternative to Caudal Block for Hypospadias Surgery: A Single-Surgeon Pilot Study

To evaluate pudendal nerve block as an alternative to caudal block for hypospadias surgery. Data were obtained by chart review. Children who underwent hypospadias repair between 2012 and 2016 by a single surgeon at an academic institution were included. Patients received ultrasound-guided pudendal block (n = 21) or caudal block (n = 19) as a regional adjunct to general anesthesia. Primary outcomes included analgesic requirement and postoperative length of stay in the recovery unit. The pudendal block cohort was slightly older (27.6 vs 18.5 months, P = .017) and had more severe hypospadias than the caudal block cohort (53% vs 35% proximal hypospadias, respectively). We detected no statistically significant difference in intraoperative opioid, postoperative opioid, or nonopioid analgesic requirement (17.9 vs 12.9 mcg fentanyl, P = .267; 0.3 vs 0.3 doses, P = .92; 0.2 vs 0.1 doses, P = .46, respectively). Postoperative length of stay was significantly shorter in the pudendal block cohort (96 vs 128 minutes, P = .016). We are the first to report the use of ultrasound-guided pudendal block for hypospadias repair. This appears to be a safe and effective alternative to caudal block with no perioperative delays. Pudendal block has several advantages over caudal block. It avoids the risks of urinary retention and lower extremity weakness and can be administered to older patients and children with spinal anomalies. Compared with caudal block, ultrasound-guided pudendal nerve block is safe, provides equivalent pain control for hypospadias repair, and results in a shorter time to discharge.

Ultrasound-guided pudendal nerve block in cats undergoing perineal urethrostomy: a prospective, randomised, investigator-blind, placebo-controlled clinical trial

The objective of this study was to evaluate the clinical usefulness, in terms of analgesic efficacy and safety, of ultrasound-guided pudendal nerve block performed with bupivacaine in cats undergoing perineal urethrostomy. Eighteen client-owned male cats scheduled for perineal urethrostomy were enrolled in the study and assigned to one of two treatment groups. The pudendal nerve block was performed under general anaesthesia, as described elsewhere, with 0.3 ml/kg of either saline (group C) or 0.5% bupivacaine (group B) - the total injection volume being split equally between the two sites of injection (left and right). Intra-operatively, assessment of nociception was based on the rescue analgesics requirement, as well as on the evaluation of changes in physiological parameters in comparison with the baseline values. Postoperative pain assessment was performed using three different pain scales at recovery and then 1, 2 and 3 h after recovery. Cats in group B showed lower heart rates and required fewer analgesics during surgery than group C. Postoperatively, group B had lower pain scores and needed less rescue buprenorphine than group C. Iatrogenic block-related complications were not observed. In conclusion, the ultrasound-guided pudendal nerve block can be considered clinically useful in feline medicine as it provides reliable analgesia in cats undergoing perineal urethrostomy.

Development of an ultrasound-guided technique for pudendal nerve block in cat cadavers

The objective of this prospective experimental cadaveric study was to develop an ultrasound-guided technique to perform an anaesthetic pudendal nerve block in male cats. Fifteen fresh cadavers were used for this trial. A detailed anatomical dissection was performed on one cat in order to scrutinise the pudendal nerve and its ramifications. In a second step, the cadavers of six cats were used to test three different ultrasonographic approaches to the pudendal nerve: the deep dorso-lateral, the superficial dorso-lateral and the median transperineal. Although none of the approaches allowed direct ultrasonographical identification of the pudendal nerve branches, the deep dorso-lateral was found to be the most advantageous one in terms of practicability and ability to identify useful and reliable landmarks. Based on these findings, the deep dorso-lateral approach was selected as technique of choice for tracer injections (0.1 ml 1% methylene blue injected bilaterally) in six cat cadavers distinct from those used for the ultrasonographical study. Anatomical dissection revealed a homogeneous spread of the tracer around the pudendal nerve sensory branches in all six cadavers. Finally, computed tomography was performed in two additional cadavers after injection of 0.3 ml/kg (0.15 ml/kg per each injection sites, left and right) contrast medium through the deep dorso-lateral approach in order to obtain a model of volume distribution applicable to local anaesthetics. Our findings in cat cadavers indicate that ultrasound-guided pudendal nerve block is feasible and could be proposed to provide peri-operative analgesia in clinical patients undergoing perineal urethrostomy.