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 Table of Contents  
Year : 2021  |  Volume : 35  |  Issue : 3  |  Page : 195-202

Redefining the efficacy of USG-Guided pudendal nerve block in pudendal neuralgia in the vulnerable section of the society

Department of Anaesthesiology, Pain Medicine and Critical Care, GTB Hospital and UCMS College, Delhi, India

Date of Submission04-Sep-2020
Date of Decision07-Dec-2020
Date of Acceptance17-May-2021
Date of Web Publication29-Dec-2021

Correspondence Address:
Dr. Suman Choudhary
Senior Resident, Department of Anaesthesiology, Pain Medicine and Critical Care, GTB Hospital and UCMS College, Delhi - 110 095
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijpn.ijpn_124_20

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Regional anesthetic blocks play a significant role not only in perioperative management but also in the holistic management of chronic intractable pain including cancer pain. Pudendal neuralgia can hamper daily life functions such as sitting, standing and sexual functions thus affecting patient's quality of life. Pudendal nerve arises from ventral divisions of S2,3,4. The nerve lies medial to the internal pudendal vessels at the level of ischial spine and is accompanied by the internal pudendal artery through the lesser sciatic foramen into the pudendal (Alcock's) canal. Pudendal Nerve is 80% sensory and 20% motor. Techniques are dependable on the precise identification of important anatomic landmark structures positioned in the close proximity of the pudendal nerve. These techniques are nerve stimulator guided, Conventional C-arm fluoroscopy guided, CT guided, Ultrasound-guided and latest being ultrasound guided accompanied with Pulsed radiofrequency. Pudendal nerve block may be performed through one the approaches: Anterior/perineal or Posterior/trans gluteal. It has got important role to play in acute and chronic perineal pain which is frequently encountered after gynecologic surgery, obstetric surgery, urologic surgery and gastrointestinal surgery. Ultrasound guided pudendal nerve block has advantages such as no radiation exposure, real time needle insertion guidance with the visualization of spread of local anesthesia. It helps to visualize not only bony structures but also vascular structures, ligaments (interspinous ligament) as well as soft tissues. However, since a lot many multi-institutional trails are needed to conducted to explore the efficacy and safety of ultrasound guided blocks for chronic pelvic pain, as it happens to be highly challenging condition to manage.

Keywords: Chronic pain, pudendal block, pudendal neuralgia, techniques of pudendal block

How to cite this article:
Saxena AK, Saboo SS, Choudhary S, Banerjee A, Bahl A. Redefining the efficacy of USG-Guided pudendal nerve block in pudendal neuralgia in the vulnerable section of the society. Indian J Pain 2021;35:195-202

How to cite this URL:
Saxena AK, Saboo SS, Choudhary S, Banerjee A, Bahl A. Redefining the efficacy of USG-Guided pudendal nerve block in pudendal neuralgia in the vulnerable section of the society. Indian J Pain [serial online] 2021 [cited 2022 Jan 19];35:195-202. Available from: https://www.indianjpain.org/text.asp?2021/35/3/195/334097

  Introduction Top

Epidemiological surveys have shown a gender difference and female preponderance in majority of chronic pelvic pain conditions encompassing endometriosis, adenomyosis, fibromyalgia, migraine and irritable bowel syndrome.[1]

Chronic pelvic pain significantly hampers life of a large number of women, with an occurrence ranging from 5.7% to 26.6%, whereas in men, it is about 8% and hence the socioeconomic effect of chronic pelvic pain is vast during their reproductive years of life.[2]

Moreover chronic perineal and chronic perianal pain can result from compression of the pudendal nerve due to various underlying causes.[3] As a consequence, pudendal neuralgia can hamper daily life functions such as sitting, standing and sexual functions thus affecting patient's quality of life.[4]

In the current scenario, regional anesthetic blocks play a significant role not only in perioperative management of various surgical conditions but also in the holistic management of chronic intractable pain including cancer pain.

In this entire review article, we have made an attempt to define the basic anatomy of pudendal nerve, its sensory and motor functions, its anatomical variations, clinical manifestation of pudendal neuralgia, various techniques of pudendal nerve block, complications and applications and the relevant evidence.

  Anatomy of Pudendal Nerve Top

Pudendal nerve is the chief nerve supplying the perineum.[5] It carries sensation originating from the external genitalia of both the sexes and the skin around the anus and rest of the perineum, as well as the motor supply to various pelvic muscles, including the male and female external urethral sphincter and the external anal sphincter.[6] The pudendal nerve arises from the ventral divisions of the S2, S3 and S4, the anatomy and function of pudendal nerve is presented in [Figure 1].
Figure 1: Anatomy and function of the pudendal nerve (Pn), formed by the roots of S2–S4. Its branches include the dorsal branch of the penis/clitoris DBp/c; the perineal branch (Pb) with its deep (d) and superficial (s) branches, as well as the inferior rectal branch (Irb) in its relation with the sacrospinous and sacrotuberous ligaments; the greater and lesser sciatic foramen; the ischial spine and the sciatic nerve (SN)

Click here to view

Pudendal nerve is 80% sensory and 20% motor.

Sensory function

The pudendal nerve gives rise to following branches:[6]

  1. Inferior rectal nerve– supplies the external anal sphincter, the lining of the lower third part of the anal canal as well as the circumanal skin. In females, it sometimes supplies sensory branches to the lower part of the vagina
  2. Perineal nerve– supplies the skin of the posterior scrotum or labia majora and minora. In females the posterior labial branches additionally supply sensory fibers to the skin of the lower vagina
  3. Dorsal nerve of the penis or clitoris– innervates the skin of the penis or clitoris and supplies the corpus cavernosum.

Motor function

Muscular branches arising from the perineal branch of the pudendal nerve supplies:[6]

  • The superficial transverse perinei
  • Bulbospongiosus
  • Ischiocavernosus
  • Deep transverse perinei
  • Sphincter urethrae
  • The anterior parts of the external anal sphincter
  • Levator ani (including the iliococcygeus, pubococcygeus and puborectalis).

The inferior rectal nerve; a branch of pudendal nerve innervates the external anal sphincter; thereby providing the voluntary/somatic control of fecal and urinary continence.

Anatomical variations

There could be lot of variation in case of pudendal nerve. Pudendal nerve may originate off the sciatic nerve and rarely from the dorsal rami of S1-S5.[6],[7]

Pudendal nerve entrapment syndrome can be classified into four subheadings on the basis of their level of compression,

  • Type 1-entrapment inferior to pyriformis muscle as the pudendal nerve exits the greater sciatic foramen
  • Type 2-most frequently encountered when entrapment occurs between sacrospinous and Sacro tuberous ligament
  • Type 3-entrapment in the pudendal canal
  • Type 4– entrapment of the terminal branches.

Diagnostic criteria (nantes criteria)[8]

Dr. Roger Robert published the Nantes criteria[8] to diagnose pudendal neuralgia as described in details below;

Inclusion criteria

  1. Pain in the area innervated by the pudendal nerve
  2. Pain more severe with sitting
  3. Pain does not awaken patients from sleep
  4. Pain with no objective sensory impairment
  5. Pain relieved by diagnostic pudendal block.

Complementary diagnostic criteria

  1. Pain is of a burning, shooting, or stabbing nature and associated with numbness
  2. Allodynia or hyperpathia
  3. Foreign body sensation or heaviness in rectum or vagina
  4. The pain progressively increases and peaks in the evening and stops when the patient sleeps
  5. Pain is more on one side
  6. Pain is more prominent posteriorly and is triggered minutes or hours after defecation
  7. Tenderness that is felt around the ischial spine during a digital vaginal or rectal examination
  8. An abnormal result on neurophysiological tests.

Exclusion criteria

  1. Pain exclusively in the territory not served by the pudendal nerve. It can be in the hypogastrium, coccyx, pubis, or gluteus
  2. Pain is associated with pruritus (more suggestive of a skin lesion)
  3. Pain entirely paroxysmal in nature
  4. An imaging abnormality can justify the cause of the pain.

[TAG:2]Differential Diagnosis[9][/TAG:2]

Since there is no confirmatory diagnostic test, pudendal neuralgia is a diagnosis of exclusion. The differential diagnosis would be as follows:

  1. Compression by an external source including a tumor or metastasis
  2. Superficial infections of the skin in the dermatomes covered by the pudendal nerve
  3. Neuropathy of the sacral region is caused by damage to the sacral nerve plexus
  4. Childbirth that causes a stretch of the perineum
  5. Complex regional pain syndrome, a chronic pain condition that causes pain in one of the limbs and usually occurs after an injury.

Clinical manifestation of pudendal neuralgia

Pudendal neuralgia patient typically complains of a sharp, shooting, stabbing, burning pain that is progressive and typically occurs with prolonged sitting. Mostly it is unilateral and dominant posteriorly and is precipitated minute or hours after defaecation. The accompanying symptoms include foreign body sensation in the patient's vagina or rectum, sometimes associated with tingling sensation and numbness and allodynia. These patients may also experience dysmenorrhea, dysuria, dyspareunia, dyschezia,[4] suprapubic pain or pain in the medial thigh.

Sometimes it's difficult to differentiate overlapping symptoms of vulvodynia and pudendal neuralgia as one syndrome may mask symptoms of the other.[10]

On clinical examination, there shall be evidence of allodynia and hyperalgesia. There is a significant compromise with the patient's quality of life.[11] The diagnosis can be extremely challenging at times.

Various techniques of pudendal block

In the literature, there are various techniques for the pudendal nerve block, and few of them are dependable on the precise identification of important anatomic landmark structures positioned in the proximity of the pudendal nerve.[12]

As per the facilities available at that time, in 1908, Mullet described the earliest transperineal (TP) approach to block the pudendal nerve.[13] The Transvaginal approach was introduced in 1954 for precise accuracy.[14]

C arm fluoroscopy-guided pudendal nerve block

Under C arm fluoroscopy, one has to attempt to aim the needle in the closest proximity of the ischial spine. Fluoroscopic guidance though helps in easy recognition of landmarks, but it fails to identify and visualize the soft tissues, structures such as interspinous ligaments and nerves, etc., Hence obviously, the interspinous ligament for pudendal nerve block is not visualized.[15]

Computed tomography guided pudendal nerve block

It is better than fluoroscopic guided pudendal nerve block but it has important limitations which include the high grade of radiation and dependence on radiologists for performing pudendal nerve block and real-time visualization is not possible in computed tomography (CT) guided.[16]


In the prone position, 5 mm parallel images are taken from the head of the femur. The exact landmark is the tip of the falciparum ligament (in CT-guided block), which is located medial to the midportion of the femoral head. With trans gluteal (TG) advancement of the 22G needle, the pudendal nerve is targeted near the ischium and medial to falciparum process between the sacrotuberal and sacrospinous ligament, subsequently nonionic contrast dye is injected in this territory of the pudendal nerve.[16]

Ultrasound-guided pudendal nerve block

Ultrasonography (USG) has advantages such as no radiation exposure, real-time needle insertion guidance with the visualization of spread of local anesthesia.[15],[17]

USG helps to visualize not only bony structures but also vascular structures, ligaments as well as soft tissues such as the ischial spine, internal pudendal artery; sacrospinous, and Sacro tuberous ligaments for higher success rates in the block.[15],[18] Thereby increasing the accuracy and safety of the procedure with the reduction in the complications.

Ultrasound-guided technique for identification and targeting the pudendal nerve was first described by Kovacs et al. at the level of the ischial spine.[19]

USG guided pudendal nerve may be performed through one of the approaches: Anterior/perineal or posterior/TG.[20],[21]

Anterior approach

The ultrasound-guided perineal approach was reported by Parras and Blanco in 2013.[15]

The pudendal nerve block is given by TP approach with the patient in lithotomy position, the pelvis was lifted by applying a pillow below and then, the pelvis was rotated ventrally, hips and knees are flexed with the legs abducted. The structures are best seen with the ultrasound probe being placed at the perineum between the scrotum or clitoris and the anus [[Figure 2] left].[15]
Figure 2: Left: Ultrasound probe in sagittal position. Right: Ultrasound image in sagittal view, a: Anterior, p: Posterior, ic: Ischiocavernosus muscle, ip b: Ischipubic branch bone

Click here to view

The best technique recommended is by identifying the reference structures in the following manner:[22]

  1. The probe is placed in the longitudinal axis at the anterior triangle, with the symphysis pubis anteriorly and the perineal body posteriorly [[Figure 2] left]. The structures seen at this level are the ischiopubic ramus and on top of it, is the ischiocavernosus muscle [[Figure 2] right]
  2. Now the probe is placed in the transverse axis of the perineal body to acknowledge the superficial and deep transverse perineal muscles [Figure 3]
  3. The posterior edge of the ischiopubic ramus is identified by moving the probe laterally whereas the internal pudendal artery is found medial to it [[Figure 4] left]
  4. In a transverse position, after recognition of the ischial tuberosity, we will be to see the pudendal artery between the bulbospongiosus and the ischium; and medial to the artery we find the perineal nerve [[Figure 4] right].
Figure 3: Left: Ultrasound probe in transversal position. Right: Ultrasound image in transverse view, pl: Lateral, am: Medial, spt: Superficial perineal transverse muscle, dpt: Deep perineal transverse muscle

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Figure 4: Left: ultrasound image in transverse view, m: medial, l: Lateral, spt: Superficial perineal transverse muscle, dpt: Deep perineal transverse muscle, color doppler shows internal pudendal artery. Right: Ultrasound image in transverse view, m: Medial, l: Lateral, ptm: Perineal transverse muscle, arrow indicates pudendal nerve

Click here to view

With 22G, 12 cm insulated needle, the block is performed at this position either in-plane from medial to lateral, or out-of-plane. The correct position of the needle is confirmed and a response obtained for the internal pudendal artery after being visualized, gentle aspiration is done and slowly the local anesthetic mix is injected while visualizing the ultrasound monitor for the spread of the local anesthetic.

Posterior approach

The pudendal nerve block through the posterior approach is given with the patient lying in lateral decubitus position with knees flexed.

The best technique recommended is by identifying the reference structures in the following manner from proximal to distal; by placing the transducer in transverse position at gluteal area:[18]

  1. Posterosuperior iliac spine
  2. Greater sciatic foramen, sacral and iliac ridge, piriformis muscle, sacral plexus, superior gluteal artery must be identified
  3. The ischial spine is recognized as a straight hyperechoic line in continuity with the sacrospinous ligament. The Sacro tuberous ligament is of light hyperechoic line that lies outside and parallels to the sacrospinous ligament; and deep to the gluteus maximus
  4. In between both ligaments (interspinous ligaments); lies the internal pudendal artery and the pudendal nerve
  5. The transducer is then moved in the same angle until the pudendal neurovascular bundle appears in the center of the ultrasound image; with 22G, 12 cm insulated needle, the block is performed at this position either in-plane from medial to lateral, or out-of-plane, as shown in [Figure 5].
Figure 5: This figure shows the relevant anatomy of the posterior approach to the pudendal nerve. Alcock canal is depicted with cyan color on the internal surface of the obturator internus (yellow asterisk), anterior to the sacrotuberous ligament (blue asterisk) in the ischioanal fossa between the obturator internus laterally, and the levator ani (magenta asterisk) and iliococcygeus (white asterisk) muscles medially. The Alcock canal contains the pudendal nerve (yellow) and the internal pudendal artery and vein (red and blue). The pudendal nerve and vessels wind around the sacrospinous ligament (green asterisk) that connects the ischial spine with the lateral margin of the sacrococcyx. At the level of the sacrospinous ligament, the pudendal nerve runs in close proximity to the inferior gluteal artery and vein (green arrow), the sacral plexus and the sciatic nerve (black asterisk). The figure shows the footprint of the US transducer (blue frame) across the posterior margin of the ischial tuberosity visualizing the pudendal nerve near the proximal end of the Alcock canal

Click here to view

Once it is in the right position, after aspiration, the local anesthetic mix is administered slowly. To relieve chronic pain, corticosteroids may be given along with local anesthetic. However, Labatt et al. found out that no significant added benefits were observed on adding corticosteroids to local anesthetics.[11]

Various complications following the pudendal nerve block[23] are as follow:

  • Pudendal vascular injury
  • Muscle pain
  • Numbness in the pudendal area
  • Fecal or urinary incontinence
  • Muscle weakness in the sciatic nerve area
  • Diminished sensation to cold.
  • Laceration of the mucosal layer of the vagina
  • Infection.

[TAG:2]Management of Pudendal Neuralgia[24],[25][/TAG:2]

Pharmacological management

Medications are typically the first treatment modalities prescribed, but they are rarely the most effective. Few such agents are listed below:

  • Muscle relaxants (tizanidine or baclofen)
  • Analgesics (nonsteroidal anti-inflammatory drugs), opioids
  • Anti-convulsants
  • Antidepressants.

Invasive intervention

These methods require precision and are performed by experienced practitioners.

  1. Pudendal Nerve Release Surgery. An entrapped pudendal nerve can be approached through 3 different types of surgeries:

    • Trans-ischio-rectal
    • TG
    • TP in some cases, patients may experience postoperative pain. In this situation, physical therapy plays a big role in recovery.

  2. Botox/botulinum toxin type A injections
  3. Pulsed radio-frequency treatment of the pudendal nerve, sacral nerve roots, or sacroiliac joints
  4. Cortisone injections
  5. Activated platelet extract injections (platelet-rich plasma)
  6. Hyaluronic acid injections
  7. Neuro-modulation with implantable electrodes.

The selection of candidates for surgery should always include a single diagnostic anesthetic injection of the pudendal nerve, as the fifth of the Nantes criteria is an effective predictor of the success of the surgery. Obvious patients are advised to try the least invasive and least risky therapies initially.

Noninvasive or conservative therapy


Long term goal is to be pain-free and improve quality of life.[24]

A physical therapy evaluation includes a movement assessment that will identify poor movement patterns that contribute to the symptoms. Treatment includes:

  • Explanation of pain mechanisms as it relates to the patient's case
  • Correction of body mechanics, position, or activity modification
  • Internal manual therapy to facilitate healthy muscle contraction and relaxation (if applicable)

Pelvic floor relaxation exercises are the most preferred strategy used by physiotherapists who specialize in pelvic floor dysfunction and disorders. This is a noninvasive approach that should be considered before more aggressive approaches be attempted.

Patient self-management

The patient should use a cushion (Doughnut or C-Shaped) that supports the ischial tuberosities to elevate the pelvic floor off the seat. This support decreases the pressure applied to the pelvic floor muscles and pudendal nerve. Avoidance of postures or movement which triggers pain.

Exercises which relax tensed pudendal nerve and will provide temporary relief are:

  • Wide leg bridges
  • Standing backward leg lifts
  • Side-lying hip abduction and extension
  • Hip extension in the quadruped position
  • Cobra pose
  • Arch backs.

The role of specific exercises or yoga asanas for chronic pudendal neuralgia appears to be a supportive measure and requires much research.

Indications of pudendal nerve block

The pudendal nerve block is mostly indicated for pain relief in:

  1. Intractable perineal pain in conditions like interstitial cystitis[26] (bladder irritation syndrome), prostatitis or epididymitis and chronic vulvodynia, endometriosis[27]
  2. In malignancy such as Ca/cervix, Ca/vagina, Ca/body of the uterus, Ca/descending colon, and Ca/rectum
  3. For diagnoses like piriformis syndrome, levator ani syndrome, lumbosacral radiculopathy, and chronic pelvic pain syndrome[22]
  4. Following surgeries in Gastroenterology like hemorrhoid,[28] anorectal and perineal surgery
  5. Following Urologic surgeries like prostate biopsy[29] penile surgeries,[30] prostate brachytherapy, circumcision, penile prosthesis operations[27],[30]
  6. Following surgeries in Gynecologic like vaginal birth, labor, episiotomies[31],[32] colpoperineorrhaphy.[27]

It has got an important role to play in acute and chronic perineal pain which is frequently encountered after gynecologic surgery, obstetric surgery, urologic surgery, and gastrointestinal surgery.[33] The underlying cause can be traumatic also like vaginal delivery.[34]

Pudendal nerve pressure neuropathy can be bicycle induced[35] and henceforth the pudendal nerve block is beneficial.

Evidence for nerve stimulator guided pudendal nerve block

During childbirth, women suffer pain from an episiotomy or perineal tears that result in the pain in the postpartum period.[36],[37] Younes et al.[32] in their double-blind study administered nerve stimulator guided pudendal nerve block to 40 young female patients undergoing medio-lateral episiotomy and assessed the pain relief with VAS at 3, 6, 12, 24, and 48 h. Patients in the pudendal group had significantly lower pain scores at 3, 6, 12, 24, and 48 h after the delivery (P < 0.05). It was observed that the pudendal nerve block provided superior analgesia while sitting and walking (P < 0.05) with less need for supplemental analgesia compared with oral analgesia.

Evidence for C arm fluoroscopy guided pudendal nerve block

Choi et al.[24] studied C arm guided pudendal nerve block in 2006 on 25 patients who had chronic perineal pain of age group 36–79 years in 2006; where they designed C, arm guided pudendal nerve block with anatomical basis and therefore chose ischial spine as the landmark for a block which was considered safe as there are no critical structures like any major vessels or nerve in the needle trajectory. They reported that C arm guided block has advantages such as its relativity, low cost, facility, accuracy, and reliability. However, they did not observe any specific spreading pattern of the contrast agent that was predictive of a successful block.

Evidence for computed tomography guided pudendal nerve block

Chronic ano-perineal pain with no proctologic, urologic or gynaecologic etiologic is frequent and difficult to manage.[31] Thoumas et al.[33] submitted in their preliminary data that in more than 90% CT guided pudendal nerve block, they obtained anesthesia of the cutaneous territory of the pudendal nerve, which confirms the accuracy of infiltration. They found no complications even after more than 200 infiltrations moreover, they found CT guidance provides an excellent landmark for infiltration.

Perineal pain can be related to the pathology of the urogenital tract.[33],[34] Source of anoperineal pain is difficult to ascertain.[35],[38] Calvillo et al.[16] used CT guided pudendal block in 2 patients; one patient (competitive cyclist) got pain relief after the block for around 24 h, whereas the other patient; a superadded superior hypogastric plexus block was required for pain relief as pudendal nerve block provided only perineal analgesia and no relief in pain. They emphasized that CT-guided block is an effective alternative to fluoroscopy in blocking pudendal nerve with more precision to the procedure.

Chronic pelvic pain has been encountered by 34% to 52% of the female population.[37],[39] Mc Donald and Spigos[40] studied 26 women with the diagnosis of pudendal neuropathy who were treated with CT guided injection therapy once a month for five total treatments each and three-quarters experienced improvements. They found the advantage of CT guided block that needle placement can be corrected by withdrawing and repositioning the needle towards the ischial spine as well as repeat CT images further assures to the operator of correct positioning. Moreover, Ct makes therapy for pudendal neuropathy more accurate and effective.

Pudendal nerve entrapment, one of the leading causes of chronic perineal pain; present as pain in the penis, scrotum, labia, perineum, or anorectal region.[2] Transient resolution of these symptoms is seen with the relaxation of obturator internus muscle by using bupivacaine injection and permanently with the neuroplastic release of the nerve to the obturator internus and the pudendal nerve.[41]

Evidence for the combined use of ultrasound and fluoroscopic guided pudendal nerve block

In a randomized controlled trial conducted by Bellingham et al.[7] on comparison of pudendal nerve block under ultrasound and fluoroscopic guidance, they stated the time to complete the block was longer under ultrasound guidance (428 [standard deviation (SD), 151)) compared to fluoroscopy (219 [SD, 65)) (P < 0.0001). However, the ease of finding structures during the pudendal nerve block was easier with ultrasound compared to fluoroscopic guided. They also found out the incidence of sciatic nerve involvement was higher with fluoroscopy as compared to ultrasound but not statistically significant when compared with ultrasound.

Evidence for ultrasound-guided pudendal nerve block in adults

Roefeel et al.[18] where he has assessed the feasibility of real-time ultrasound for pudendal nerve block in patients with chronic perineal pain in 17 patients found out that real-time ultrasound can be used to obtain high-quality images of anatomical landmarks around the ischial spine and for the advancement of the needle to target pudendal nerve with monitoring of the spread of local anesthetic as a hypoechoic collection around the nerve. Following the procedure, it was observed that all 17 patients developed perineal sensory block.

Chronic pelvic pain can present in various pain syndromes such as pudendal neuralgia, piriformis syndrome, and border nerve syndrome.[38] Peng et al.[22] in their study on ultrasound-guided interventional procedures in chronic pelvic pain noted that ultrasound-guided nerve block allows real-time needle advancement and confirmation of injectate spread within the interligamentous plane. They also stated that it allows visualization of various tissues and improves the accuracy of needle placement as exemplified by various interventional procedures in the pelvic regions.

The prostate biopsy has been one of the most commonly performed urological procedures. Iremashvili et al.[29] in a randomized trial added the pudendal block to periprostatic anesthesia for TP ultrasound-guided prostate biopsy where the group receiving combined anesthesia showed statistically significant control in pain during probe insertion, biopsy puncture, and at 1 h after biopsy with mean pain scores of 1.83 ± 0.65 as compared to other groups, who received only periprostatic anesthesia of 2.41 ± 1.01.

The preliminary data by Fichtner Bendsten et al.[21] where he has given ultrasound-guided pudendal nerve block at the entrance of Alcock's canal; shows that with this technique there is minimal to almost nil spread of local anesthesia to sacral plexus. So, with this block at the location of the proximal end of Alcock's canal (proximal to branching of the inferior rectal nerve), there is no local anesthesia spread to the sacral plexus.

Parras and Blanco[15] in 2016 studied the anterior approach for ultrasound-guided pudendal nerve block by scanning 56 perineal areas of 28 patients bilaterally. They implied that the best way to give ultrasound-guided pudendal nerve block is by identifying the nerve by placing the USG probe transversal to the line between scrotum or mons pubis and the anal margin that is medial to the ischial tuberosity. This helps to identify the pudendal nerve coursing along with the transverse perineal muscle and medial to the pudendal artery. The wide availability of ultrasound techniques helps in understanding pelvic floor anatomy and better placement of successful blocks.

Pudendal nerve blocks have broad spectrum in clinical applications. However, in-depth knowledge is required for pudendal nerve anatomy for a successful block.

Evidence for ultrasound-guided pudendal block in children

Though; TP pudendal nerve block has been utilized in pediatric anesthesia under the guidance of nerve stimulator, as an alternative to caudal block.[42],[43] However, the complications like puncturing of the rectum or even an intravascular injection are common in the blinded technique. Recently, Ferrand et al.[44] adopted a new technique ultrasound-guided pudendal nerve block of 60 children of the age group of 1–15 years, ASA grade I-III undergoing elective perineal surgery under general anesthesia. The pudendal nerve block was performed under USG with “out of plane” approach after precisely locating the ischial tuberosity, rectum, pudendal artery, and pudendal nerve. They identified the failure of the pudendal block by an increase in MAP >80% compared to the baseline value after surgical incision. In their experience, the quality of USG image was good in 81% of the block with easy visualization of ischium and rectum in >95%. The localization of the tip of the needle was clear in all pudendal nerve blocks and the spread was seen in 79%. The pudendal nerve block was effective in 88% of pediatric patients.

Ultrasound-guided pulsed radiofrequency for pudendal neuralgia

Pudendal neuralgia is an important cause of chronic pelvic pain. Very recently, Frank et al.[41] utilized transvaginal pulsed radiofrequency for the management of pudendal neuralgia in women in whom conservative management did not prove to be effective. In their case series of 7 patients, the mean age was 43.7 years (SD-7.97) and the average number of pulsed radiofrequency treatment was 4.43 (range 1–12) and the duration of relief was an average of 11.4 weeks (SD-3.09). They did not report any major or minor complications during the procedure or following the procedure.

  Conclusion Top

Pudendal neuralgia is a chronic disabling condition that is mostly underdiagnosed and inappropriately treated and causes significant impairment of quality of life. The treatment options include pharmacological therapy, CT/fluoroscopy-guided blocks, USG-guided blocks, decompression surgery, Pulsed radiofrequency, ablation of the pudendal nerve, and sacral neuromodulation, especially in ladder augmentation procedures for interstitial cystitis or vulvodynia. Recently ultrasound-guided blocks are being clinically utilized in the multimodal management of chronic pain. USG has advantages such as no radiation exposure, real-time needle insertion guidance, avoidance of vascular trauma with the added advantage of visualization of the spread of the local anesthetic agent. The USG procedure is quick, safe, and easily performed, and it may offer considerable relief of symptoms. Despite recent advances and significant improvements in pain control over the last two decades, intractable pelvic pain continues to be an important global public health concern. Pelvic pain patients are essentially emotionally more disturbed and respond less well to the treatment offered. Chronic pelvic pain is like an intractable headache in the pelvis and is a complex multifactorial pain syndrome. An integrated approach encompassing psychiatric counseling, appropriate medications and as described above the USG guided pudendal nerve block as in intractable chronic perineal pain, levator ani syndrome, etc., or fluoroscopy-guided/USG guided superior hypogastric plexus block depending upon the underlying chronic gynecological condition like carcinoma ovary, carcinoma cervix, etc., Last but not the least we must adopt a holistic approach in the management of chronic pelvic pain, ensuring that the most important clinical interventions are empathy, hope, and ongoing support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]


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