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

Background: 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.
Aims: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
(© 2017 John Wiley & Sons Ltd.)