Pudendal Nerve Block
Distribution of the Pudendal Nerve:
S2-S4 nerve roots and branches into inferior rectal nerve, perineal nerve and then the dorsal nerve of penis/clitoris
Sensory innervation to the external genitalia, perineum, anus
Motor innervation to muscles of perineum/pelvic floor
Clinical Uses: Perineal and anal analgesia
Procedures on the external genitalia
Hemorrhoidectomy
Technique:
Ultrasound guided, out-of plane approach
Patient position: Lithotomy (ideally with assistant holding feet/legs, folded sheet/towel under bottom)
Probe position: Horizontally, parallel to floor at 3- and 9-o’clock from anus
Landmarks: ischial tuberosity
Aim to have ischial tuberosity on lateral aspect of the screen and advance the needle to hit bone on medial aspect of ischial tuberosity, then slowly walk off of the ischial tuberosity until the needle is placed just medially to the ischium. After negative aspiration, the local deposition should be noted by seeing tissue displacement medially to the ischium.
Potential Complications:
Block failure
Intravascular injection
Infection
Anal sphincter functional dysfunction (aka anal leakage)
The two mainstays of penile surgery are penile blocks and a caudal. Much of the more recent evidence suggests a pudendal block is superior to both.
In a prospective, randomized, double blind study, Tutuncu et al compared a penile nerve block (PNB) versus pudendal nerve block (PB) as analgesic adjunct to general anesthetic. There were 39 patients in each group. Postoperative pain evaluation was significantly higher in PNB versus PB. Intraoperatively, 2 patients in PB group versus 18 in PNB group required supplemental opioid (remifentanil infusion). Patients who received PB did not require supplemental analgesics until 24 hours postop whereas 38.4% of patients who received PNB required supplemental analgesics 5 minutes postoperatively.
Naja et al compared pudendal vs dorsal nerve block in a prospective RCT for circumcision. Intraoperatively, 4 patients in dorsal group required supplemental local infiltration versus zero patients in pudendal group. Additionally, 2 patients in dorsal group had complete block failure. There was Improved surgical and parental satisfaction seen in PB group, significantly lower pain scores seen in 1st 12 hours in the pudendal group, and proportion of patients who took analgesics during 1st 6hr postoperatively was higher in DNB group.
In a single center, single surgeon retrospective review of ultrasound guided pudendal nerve block (PB) versus caudal block (CB) for hypospadias repair, Hecht et al found no difference in time required to place PB versus CB, comparable complication rates, and similar intraoperative opioid or postoperative opioid/non-opioid requirements. Moreover, in a prospective RCT Kendigelen et al compared pudendal vs. caudal in hypospadias repair. A single anesthesiologist performed all blocks. Intraoperatively, 3 patients required opioid supplementation in the caudal group vs zero patients in PB group. Postoperatively in PACU, no patients in PB required supplemental analgesia whereas 10 patients (25%) in CB group required additional analgesics. Additionally, PB group had lower pain intensity at 24 hours – 3 patients in PB required additional analgesics at 24 hours compared with all of the patients in the CB group. Parent satisfaction scores were higher in PB group versus CB group.
Furthermore, in a prospective, randomized, double-blinded study Naja et al compared caudal vs pudendal for hypospadias repair. They also found no significant difference in time to perform the block (3-5 min) between groups. Postoperatively, less patients consumed analgesics in the first 24hrs in the pudendal group, while the average amount of analgesics consumed per patient in the first 24 hours was higher in the caudal group. Of note, 4 patients in CB group had incomplete block and required supplemental fentanyl. Surgeon and parental satisfaction was higher in pudendal group.
Seemingly more reliable, longer-lasting, with higher surgeon and parental satisfaction, the pudendal nerve block may become the gold standard for male penile surgery.
Osmani, F., Ferrer, F. and Barnett, N.R., 2021. Regional anesthesia for ambulatory pediatric penoscrotal procedures. Journal of Pediatric Urology.
Tutuncu AC, Kendigelen P, Ashyyeralyeva G, Altintas F, Emre S, Ozcan R, Kaya G. Pudendal nerve block versus penile nerve block in children undergoing circumcision. Urol J. 2018 May 3;15(3):109-115. doi: 10.22037/uj.v0i0.4292
Naja Z, Al-Tannir A, Faysal W, Daoud N, Ziade F, El-Rajab M. A comparison of pudendal block vs dorsal penile nerve block for circumcision in children: a randomized controlled trial. Anaesthesia. 2011 Sep;66(9):802-7. doi: 10.1111/j.1365-2044.2011.06753.x
Hecht S, Pineda J, Bayne A. Ultrasound-guided pudendal block is a viable alternative to caudal block for hypospadias surgery: a single-surgeon pilot study. Urology. 2018 Mar;113:192-196. doi: 10.1016/j.urology.2017.11.006
Kendigelen P, Tutuncu AC, Emre S, Altindas F, Kaya G. Pudendal versus caudal block in children undergoing hypospadias surgery, a randomized controlled trial. Reg Anesth Pain Med. 2016 Sep-Oct;41(5):610-5. doi: 10.1097/AAP.0000000000000447
Naja Z, Ziade F, Kamel R, El-Kayali S, Daoud N, El-Rajab MA. The effectiveness of pudendal nerve block versus caudal block anesthesia for hypospadias in children. Anesth Analg. 2013 Dec;117(6):1401-7. doi: 10.1213/ANE.0b013e3182a8ee52
