Pudendal Nerve Block: Procedure for Pelvic Pain Relief

A pudendal nerve block is an injection of local anesthetic around the pudendal nerve, the main nerve supplying sensation to the perineum, genitals, and anus. It numbs the region for hours, and its uses range from childbirth pain relief and hemorrhoid surgery to diagnosing chronic pelvic pain conditions. The procedure has been around for decades in obstetrics but is gaining fresh attention as ultrasound guidance makes it more precise and as researchers find it outperforms several alternative blocks for specific surgeries.

Where the Pudendal Nerve Runs and Why That Matters

The pudendal nerve originates from the lower sacral spine, exits the pelvis through the greater sciatic notch, hooks around the ischial spine (the small bony prominence you can feel deep in each buttock), and re-enters through the lesser sciatic notch into a tunnel of connective tissue called the pudendal canal, sometimes called Alcock’s canal. From there it branches into three main divisions: the inferior rectal nerve (serving the anus and surrounding skin), the perineal nerve (serving the perineum, labia or scrotum, and parts of the vagina or urethra), and the dorsal nerve of the penis or clitoris. Cadaver studies confirm the nerve is consistently anchored by connective tissue to the junction of the sacrospinous ligament and ischial spine, which is exactly the landmark clinicians aim for when performing the block.

1Journal of Minimally Invasive Gynecology. Anatomic Variations of the Pudendal Nerve and Its Local Branches Relative to Pelvic Landmarks

Because a single nerve trunk carries sensation for such a wide territory, blocking it at one point can numb the entire perineal region on that side. That efficiency is the block’s main advantage over injecting local anesthetic at multiple individual sites, and it explains why the procedure suits such a wide range of clinical situations.

How the Block Is Performed

There are several approaches, and the choice depends on the clinical setting, available equipment, and whether the patient is awake or under general anesthesia.

Finger-Guided Transvaginal Approach

This is the traditional technique, often used during labor. The clinician inserts two fingers vaginally to feel for the sacrospinous ligament and ischial spine. A long needle is then guided alongside the fingers and advanced about 10 mm behind and toward the midline of the ischial spine. After confirming the needle is not inside a blood vessel (by pulling back slightly on the syringe plunger), the anesthetic is injected.

2PubMed Central. Comparison of Ultrasound-Guided Transgluteal and Finger-Guided Transvaginal Pudendal Nerve Block Techniques: Which One is More Effective?

Ultrasound-Guided Approach

Increasingly, clinicians use an ultrasound probe to visualize the bony landmarks and, in some cases, the pudendal artery running alongside the nerve. One well-described route follows the hip bone sonographically along the greater sciatic notch, past the ischial spine, and into the lesser sciatic notch to target the nerve inside Alcock’s canal.

3Regional Anesthesia & Pain Medicine. Ultrasound-Guided Pudendal Nerve Block at the Entrance of the Pudendal (Alcock) Canal: Description of Anatomy and Clinical Technique

In pediatric patients, a transperineal ultrasound-guided approach has been described, with the probe placed between the anus and the base of the scrotum. Landmarks include the ischial tuberosity, rectum, and pudendal artery.

4PubMed. Ultrasound-guided pudendal nerve block in children: A new technique of ultrasound-guided transperineal approach

CT-Guided Approach

For chronic pain patients who need very precise needle placement, CT imaging can guide the injection directly into the pudendal canal. In one study of 52 CT-guided blocks in 31 patients with chronic pelvic pain, the procedure was technically successful every time, with average pain scores dropping from about 6 out of 10 before the block to about 2 out of 10 afterward.

5PubMed. CT-guided nerve block for pudendal neuralgia: diagnostic and therapeutic implications

Pain Relief During and After Childbirth

Pudendal nerve blocks have a long history in obstetrics. In a Norwegian national survey, the most common reasons midwives used the block were to relieve pain during the pushing phase of labor (about two-thirds of respondents), to manage an early urge to push (about 60%), and as an alternative when epidural analgesia was not available (about 57%). Roughly half also used it for pain relief during perineal suturing after delivery.

6European Journal of Midwifery. Use of pudendal nerve block among midwives in Norway: A national cross-sectional study

A randomized controlled trial specifically looking at episiotomy pain found that women who received a pudendal block had significantly lower pain scores at rest for up to 48 hours compared with women who received a placebo injection. The difference held whether the women were resting, sitting, or walking. Only about 15% of the block group needed additional pain medication, compared with 85% of the placebo group.

7PubMed. A randomized controlled trial of pudendal nerve block for pain relief after episiotomy

The block does not numb the uterus or upper vagina, so it is not a substitute for epidural analgesia during active contractions. Its sweet spot is the later stages of delivery and the immediate postpartum period, when perineal pain from stretching, tearing, or suturing is the main concern. In settings where epidural services are limited or where a patient arrives too late for an epidural, it can be a fast, practical option.

Hemorrhoid and Anorectal Surgery

Hemorrhoidectomy is notoriously painful, and the pudendal nerve block has emerged as one of the better tools for managing that pain. A systematic review and meta-analysis pooling double-blind randomized trials found that patients who received a pudendal block had substantially lower pain scores within the first 6, 12, and 24 hours after surgery compared with controls. The advantage faded by 48 hours, suggesting the block’s main benefit is covering the acute pain window when discomfort is most intense.

8PubMed Central. The role of pudendal nerve block in hemorrhoid surgery: a systematic review and meta-analysis of double-blind randomized controlled trials

A separate randomized trial comparing pudendal nerve block to local anesthetic wound infiltration (where the surgeon injects the anesthetic directly into the surgical site) found that the block group had lower pain scores at 6, 12, and 18 hours, needed less supplemental tramadol, and had fewer episodes of anal sphincter spasms. The block group also scored higher on a quality-of-recovery questionnaire at 24 hours.

9SpringerLink. Ultrasound-guided pudendal nerve block for postoperative pain management in procedures for prolapse and hemorrhoids: a randomized, double-blinded trial

An older trial using bupivacaine for the block reported a mean analgesic duration of nearly 24 hours, compared with under 4 hours for a control technique.

10PubMed. Pudendal block with bupivacaine for postoperative pain relief

That kind of duration means patients may sleep through the worst of the postoperative pain and wake up on the downslope.

Pediatric Perineal Surgery

In children, the pudendal block is most studied for hypospadias repair, a surgery to correct the urethral opening on the penis. The traditional regional technique for this surgery is a caudal block (an injection into the epidural space at the base of the spine), but several randomized trials have found the pudendal block delivers longer-lasting pain relief.

One trial showed that children in the pudendal block group had lower pain scores at 6, 12, 18, and 24 hours and waited significantly longer before needing their first dose of rescue medication, while the caudal block group required more paracetamol overall.

11PubMed Central. Optimizing Paediatric Hypospadias Surgical Repair: Pudendal Nerve Block Versus Caudal Block for Superior Analgesia

Another randomized trial found that only three patients in the pudendal group needed any additional pain medication within 24 hours, versus every single patient in the caudal group. Family satisfaction was also higher with the pudendal block.

12Regional Anesthesia & Pain Medicine. Pudendal Versus Caudal Block in Children Undergoing Hypospadias Surgery: A Randomized Controlled Trial

A recent meta-analysis pooling these and other trials confirmed the pattern: the pudendal block produced lower pain scores at 6, 12, and 24 hours with reduced overall painkiller consumption compared with caudal block.

13medRxiv. Analgesic Efficacy and Safety of Caudal Epidural, Dorsal Penile Nerve, and Pudendal Nerve Blocks in Hypospadias Repair Surgery in Children: Updated Meta-Analyses

An interesting pharmacology question in this setting is whether adding intravenous dexamethasone (a steroid often used to extend block duration in other nerve blocks) makes the pudendal block last longer. One trial found that dexamethasone improved pain scores between 6 and 24 hours and cut the percentage of children needing rescue medication roughly in half.

14PubMed Central. The potentiating effect of intravenous dexamethasone upon preemptive pudendal block analgesia for hypospadias surgery in children managed with Snodgrass technique: a randomized controlled study

However, a second randomized trial specifically measuring time to first painkiller use found no significant difference between the dexamethasone and control groups, with both wearing off after roughly five and a half to six and a half hours.

15PubMed. Intravenous dexamethasone does not prolong the duration of pudendal nerve block in infants and children undergoing hypospadias surgery: A randomized clinical trial

The answer is not settled, and the discrepancy may come down to differences in anesthetic drugs, dexamethasone doses, or how outcomes were measured.

Other Surgical Applications

Researchers have also tested the block in less obvious settings. For men undergoing inflatable penile prosthesis implantation, adding a pudendal block to general anesthesia cut the time spent in the recovery room by more than an hour on average and reduced the number of patients who called for pain medication afterward. Fewer patients in the block group needed any postoperative opioids at all compared with the no-block group.

16PubMed Central. Pudendal nerve block decreases narcotic requirements and time spent in post-anesthesia care units in patients undergoing primary inflatable penile prosthesis implantation

In cervical brachytherapy, where a radiation applicator is placed into the cervix and the perineum can be quite tender, the block has been used as part of a multimodal analgesia protocol. A study evaluating that application found no instances of bleeding, nerve damage, organ injury, or systemic local anesthetic toxicity related to the block itself.

17Clinical and Translational Radiation Oncology. Efficacy and safety of the pudendal nerve block as a component of multimodal analgesia for cervical brachytherapy

Diagnosing Chronic Pelvic Pain

Beyond its role in acute pain, the pudendal nerve block has a distinct diagnostic function. Pudendal neuralgia, a condition in which the pudendal nerve is irritated or compressed, causes burning, stabbing, or aching pain in the perineum that typically worsens with sitting. The internationally recognized Nantes criteria for diagnosing pudendal neuralgia by nerve entrapment list five essential features, and one of them is a positive response to a pudendal nerve block. In other words, if injecting anesthetic around the nerve temporarily relieves the patient’s pain, that supports the diagnosis.

18PubMed. Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria)

This diagnostic use is especially valuable because pudendal neuralgia often overlaps with other conditions like interstitial cystitis, vulvodynia, or chronic prostatitis. Imaging cannot reliably show the nerve itself, and there is no blood test. A block that temporarily erases the pain helps clinicians isolate the nerve as the pain generator and identify patients who might benefit from surgical decompression.

19PubMed. Role of nerve block as a diagnostic tool in pudendal nerve entrapment

In the CT-guided study described earlier, 14 of the 31 chronic pain patients went on to surgery after the block confirmed the diagnosis. All 14 improved with surgical nerve release, suggesting the block accurately identified the right candidates.

20PubMed. CT-guided nerve block for pudendal neuralgia: diagnostic and therapeutic implications

When the Block Is Not Enough for Chronic Pain

A single pudendal nerve block with local anesthetic provides temporary relief, typically lasting hours to days. For patients with chronic pudendal neuralgia, that is useful for diagnosis but not as a long-term treatment on its own. Repeated blocks with added corticosteroids can extend relief, and some patients do well with a series of injections. But for many, the pain returns.

Pulsed radiofrequency treatment is one step beyond a simple block. It uses the same needle-to-nerve approach but delivers short bursts of electrical energy that modulate nerve signaling without destroying tissue. A randomized controlled trial compared pulsed radiofrequency to a standard nerve block in patients with pudendal neuralgia. At three months, 92% of the radiofrequency group reported clinical improvement, compared with about 36% of the nerve-block-alone group. The radiofrequency group also had lower depression scores and used less pain medication.

21PubMed Central. Clinical effect and safety of pulsed radiofrequency treatment for pudendal neuralgia: a prospective, randomized controlled clinical trial

When a confirmed diagnostic algorithm points to nerve entrapment, the results of the block guide whether a patient is suitable for surgical decompression, where a surgeon physically frees the nerve from surrounding tissue.

22Medicina Clínica (English Edition). Diagnostic and therapeutic algorithm for pudendal nerve entrapment syndrome

Safety Profile

Serious complications from pudendal nerve blocks are rare. The main risks are accidental injection into the pudendal vessels (which is why clinicians aspirate before injecting), infection at the injection site, and temporary numbness extending beyond the intended area. Across multiple studies in surgical, obstetric, and chronic pain settings, no significant bleeding, organ injury, or systemic toxicity events have been reported.

23Clinical and Translational Radiation Oncology. Efficacy and safety of the pudendal nerve block as a component of multimodal analgesia for cervical brachytherapy

One side effect worth knowing about is urinary retention, the temporary inability to empty the bladder. Because the pudendal nerve also supplies the external urethral sphincter, blocking it can make it harder to urinate in the hours after surgery. However, a meta-analysis of randomized trials in hemorrhoidectomy found that urinary retention was actually less common in patients who received a pudendal block (about 3.5%) compared with control groups (about 7.4%).

24ScienceDirect / Asian Journal of Surgery. Assessment of the efficacy and safety of pudendal nerve block in post-hemorrhoidectomy pain: A meta-analysis of randomized controlled trials

That likely reflects the fact that severe postoperative pain itself inhibits bladder function, so better pain control paradoxically reduces retention rather than causing it.

Pudendal Block Versus Caudal Block

In pediatric and some adult perineal surgeries, the caudal block is the traditional comparison. The caudal block is quicker to perform and has a slightly higher initial success rate. One study found the caudal block took about 10 minutes to set up versus 17 minutes for the pudendal block, with a success rate of 90% versus 83%.

25Regional Anesthesia & Pain Medicine. Comparison of ultrasound-guided pudendal nerve block with caudal block for postoperative analgesia in children undergoing perineal surgeries under general anesthesia

But duration is where the pudendal block pulls ahead. In that same study, the average time to first rescue medication was over 17 hours in the pudendal group versus about 4 hours in the caudal group. The caudal block also caused more motor blockade in the legs, which delays discharge. The pudendal block keeps the numbness confined to the perineum, so children can move their legs normally as soon as they wake up.

The tradeoff is real: the pudendal block requires more skill and takes longer to place, but it delivers more targeted, longer-lasting pain relief with fewer systemic effects. For a quick procedure where the patient will be awake soon, that duration advantage often tips the balance.

Veterinary Research and What It Tells Us

Interestingly, the pudendal nerve block is being developed for dogs as well. Veterinary anesthesiologists have described ultrasound-guided approaches in canine cadavers, identifying the urethra, perineal arteries, and surrounding muscles as landmarks. In one cadaver study, dye injection successfully stained about 25 mm of each pudendal nerve, confirming accurate spread.

26PubMed. Ultrasound-guided pudendal block in the dog: a cadaver study and case report

A second study using a different transgluteal approach achieved complete nerve staining in roughly 60 to 70% of injections.

27PubMed. Ultrasound-guided ischiorectal fossa block targeting the pudendal nerve in dogs: a cadaveric study

These studies matter beyond veterinary medicine because canine anatomy shares enough similarities with human anatomy that refining techniques in dogs can inform human approaches, and the success-rate data gives a sense of how reliably ultrasound guidance can target a nerve that sits deep in the pelvis. The fact that even in dogs the staining rate is not 100% reinforces why imaging guidance keeps improving and why clinicians sometimes need to repeat or adjust the injection in clinical practice.