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

Anatomy of the pudendal nerve in clinically important areas: a pictorial essay and narrative review

PURPOSE

The pudendal nerve is an anatomical structure arising from the ventral branches of the spinal roots S2-S4. Its complex course may be affected by surrounding structures. This may result in irritation or entrapment of the nerve with subsequent clinical symptoms. Aim of this study is to review the anatomy of the pudendal nerve and to provide detailed photographic documentation of the areas with most frequent clinical impact which are essential for surgical approach.

METHODS

Major medical databases were searched to identify all anatomical studies investigating pudendal nerve and its variability, and possible clinical outcome of these variants. Extracted data consisted of morphometric parameters, arrangement of the pudendal nerve at the level of roots, formation of pudendal nerve, position according to sacrospinal and sacrotuberal ligaments and its terminal branches. One female cadaver hemipelvis was dissected with common variability of separate course of inferior rectal nerve. During dissection photodocumentation was made to record course of pudendal nerve with focus on areas with recorded pathologies and areas exposed to iatrogenic damage during surgical procedures.

RESULTS

Narrative review was done to provide background for photodocumentation. Unique photos of course of the pudendal nerve was made in areas with great clinical significance.

CONCLUSION

Knowledge of anatomical variations and course of the pudendal nerve is important for examinations and surgical interventions. Surgically exposed areas may become a site for iatrogenic damage of pudendal nerve; therefore, unique picture was made to clarify topographic relations.

Sonoanatomy of the ilioinguinal, iliohypogastric, genitofemoral, obturator, and pudendal nerves: a practical guide for US-guided injections

The ilioinguinal, iliohypogastric, genitofemoral, obturator, and pudendal nerves are the major sensory nerves that may be involved in chronic groin and genital pain with a significant impact on the quality of life of patients. The diagnosis remains clinical, and US-guided diagnostic injections using an anesthetic may aid in confirming the clinical suspicion. The anatomy of the peripheral nerves can be successfully studied using imaging. High-resolution ultrasound is increasingly used in the clinical setting for visualizing small peripheral nerves, and magnetic resonance imaging provides an anatomical overview of the relationship between small nerves and surrounding structures. In this pictorial assay, we review the anatomy and clinical relevance of the ilioinguinal, iliohypogastric, genitofemoral, obturator, and pudendal nerves. We summarize the various techniques for ultrasound identification, and present the ultrasound-guided infiltration techniques for injecting the ilioinguinal, iliohypogastric, genitofemoral, obturator, and pudendal nerves. Corresponding magnetic resonance images and clinical photos of the probe placement technique are provided for anatomical correlation. This paper is aimed to serve as a practical technical guide for physicians to familiarize themselves with the ultrasound anatomy of the major inguinal sensory nerves and to enable successful ultrasound identification and ultrasound-guided diagnostic or therapeutic infiltrations for pain management of the ilioinguinal, iliohypogastric, genitofemoral, obturator, and pudendal nerves.

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.

Regional anaesthesia for labour, operative vaginal delivery and caesarean delivery: a narrative review

This narrative review discusses recent evidence surrounding the use of regional anaesthesia in the obstetric setting, including intrapartum techniques for labour and operative vaginal delivery, and caesarean delivery. Pudendal nerve blockade, ideally administered by an obstetrician, should be considered for operative vaginal delivery if neuraxial analgesia is contraindicated. Regional techniques are increasingly utilised in clinical practice for caesarean delivery to minimise opioid consumption, reduce pain, improve postpartum recovery and facilitate earlier discharge as part of enhanced recovery protocols. The evidence surrounding transversus abdominis plane and quadratus lumborum blockade supports their use when: long-acting neuraxial opioids cannot be administered due to contraindications; if emergency delivery necessitates general anaesthesia; or as a postoperative rescue technique. Current data suggest quadratus lumborum blockade is no more effective than transversus abdominis plane blockade after caesarean delivery. Transversus abdominis plane blockade, wound catheter insertion and single shot wound infiltration are all effective techniques for reducing postoperative opioid consumption, with transversus abdominis plane blockade favoured, followed by wound catheters and then wound infiltration. Ilio-inguinal and iliohypogastric, erector spinae plane and rectus sheath blockade all require further studies to determine their efficacy for caesarean delivery in the presence or absence of long-acting neuraxial opioids. Future studies are needed to: compare approaches for individual techniques; determine which combinations of techniques and dosing regimens result in optimal analgesic and recovery outcomes following delivery; and elucidate the populations that benefit most from regional anaesthesia in the obstetric setting.