Ultrasound-Guided Pudendal Nerve Block for Intra and Postoperative Pain Management in Pediatric Penoscrotal Surgery
In this video, a bilateral ultrasound-guided pudendal nerve block is demonstrated on a 15-month-old healthy child undergoing circumcision and penoscrotal fusion repair. After the induction of general anesthesia, a nerve block time-out is conducted. Subsequently, the patient is positioned in the frog-leg stance by an assistant, and the perineum is cleaned using chlorhexidine. Using a high-frequency linear ultrasound probe, the ischiorectal fossa is identified between the ischial tuberosity and the anus at the 3 and 9 o’clock positions relative to the anus. A 22-gauge, 50-millimeter-long Pajunk needle is then inserted using an out-of-plane technique, advanced 1-2 cm deep and medial to the ischial tuberosity, until a subtle change in resistance or “pop” is felt, confirming the correct placement below the sacrospinous ligament. The local anesthetic (0.3 to 0.5 mL/kg of 0.2% Ropivacaine or 0.25% Bupivacaine on each side) is then incrementally injected, observed as spreading medially and beneath the ischial tuberosity. The block is then repeated on the other side. Our patient tolerated the procedure well and did not require any opioids intraoperatively, postoperatively in the post-anesthesia care unit, or at home following discharge.
Equipment needed: - High-frequency linear ultrasound probe - Sterile ultrasound probe cover - 50 mm hyperechoic nerve block needle - Ropivacaine 0.2% or Bupivacaine 0.25% - 10 mL syringe - Normal saline syringe for hydro dissection - Chlora Prep sticks - Sterile gloves Procedure: Following induction of anesthesia and securing the airway, position the patient in frog leg position. This can be easily achieved in small children by having someone flex the legs upward and bringing the soles of the feet together. Place a folded towel underneath the pelvis to raise the perineum from the OR bed. This will allow better access for hand and ultrasound maneuvering. Begin by placing the ultrasound transducer on the perineum at the 9 o'clock position in relation to the anus. Scan this area to visualize the ischial tuberosity, recognizable as a hyperechoic dome. At this level, the pudendal nerve and artery traverse through Alcock's Canal, typically located medially and 1-2 cm deep to the ischial tuberosity, although rarely visible under ultrasound. The needle is introduced medially to the ischial tuberosity, parallel to the ultrasound beam. Although considered an out-of-plane technique, due to the parallel alignment of the needle and ultrasound beam, the entire distal portion of the needle can be visualized throughout the procedure. Upon advancing the needle 1-2 cm deep and medial to the ischial tuberosity, a noticeable change in resistance or "pop" may be felt. Our target, or the plane where the pudendal nerve travels is found under the sacrospinous ligament. Inject 0.2 to 0.3 mL of 0.2% Ropivacaine or 0.25% Bupivacaine into this plane. Correct anesthetic spread is confirmed when local anesthetic tracks medially and beneath the ischial tuberosity. Incorrect site of injection is observed when the spread of local anesthetic tracks laterally or superficial to the ischial tuberosity. For a left pudendal nerve block, position the ultrasound transducer at 3 o'clock on the perineum and follow the same steps.
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