Getting an Accurate Diagnosis: The Nantes Criteria

Getting a diagnosis for chronic pelvic pain can be a long journey, but for Pudendal Nerve Entrapment Syndrome (PNES), there is a gold-standard roadmap. This roadmap is known as the Nantes criteria, a set of five specific rules developed by experts to help doctors identify when the pudendal nerve is the true source of your pain ^[1][2].

The 5 Mandatory Nantes Criteria

To be formally diagnosed with pudendal neuralgia due to entrapment, you generally must meet all five of these criteria ^[2][3]:

1. Pain in the Pudendal Territory: The pain must be located in the areas served by the nerve, which include the perineum, genitals, and around the anus ^[1][2].
2. Pain Worsened by Sitting: This is the hallmark sign. If sitting makes the pain significantly worse, it suggests the nerve is being mechanically compressed ^[1][4].
3. The Pain Does Not Wake You at Night: Unlike some other conditions, PNES pain typically subsides when you lie down to sleep. Note: You may still struggle to fall asleep initially due to residual pain from the day, but if your pain is so severe that it consistently wakes you from a deep sleep, doctors may look for other causes ^[1][2].
4. No Objective Sensory Loss: While you may feel burning or “weird” sensations, a physical exam should not show a total loss of feeling (numbness) in the area ^[1][3].
5. Relief from a Diagnostic Nerve Block: This is often considered the most critical test. A doctor injects a numbing agent (anesthetic) near the nerve. If your pain disappears or significantly decreases while the area is numb, it confirms the pudendal nerve is the culprit ^[1][5][6].

“Red Flags” and Exclusion Criteria

Specialists also look for signs that point away from PNES. These “red flags” suggest the cause might be something else, such as a spinal problem or a different nerve issue ^[1]:

• Pain that is strictly limited to one tiny, pinpointed spot (which might suggest a small nerve growth called a neuroma) ^[1].
• The presence of a neurological deficit, such as true muscle weakness in the legs ^[1].
• Imaging (like an MRI of the spine) that shows a different clear cause for the pain, such as a herniated disc ^[7][2].

The Role of the Diagnostic Block

The pudendal nerve block (PNB) is both a test and a clue. It is typically performed using ultrasound or CT guidance to ensure the needle reaches the exact right spot near the ischial spine (a bony landmark in the pelvis) or Alcock’s canal ^[6][8].

A “positive” block doesn’t necessarily mean the relief will last forever—it is a diagnostic tool meant to see if numbing that specific nerve stops your pain ^[5]. If it does, even for just a few hours, it provides strong evidence that the nerve is trapped ^[1][9].

Is Imaging Necessary?

While the diagnosis is primarily clinical (based on your symptoms and the nerve block), doctors may use MR neurography (a specialized MRI for nerves) ^[10]. This can help:

• Rule out other pelvic pathologies like cysts or tumors ^[1][11].
• Visualize the nerve to see if it looks inflamed or compressed at a specific site ^[12][13].
• Assist in planning for surgery if conservative treatments don’t work ^[12].

Diagnostic Checklist

If you suspect PNES, your diagnostic process should generally include:

• [ ] A detailed review of your pain patterns (especially sitting vs. standing).
• [ ] A physical exam to check for tenderness over the ischial spine or Alcock’s canal ^[14].
• [ ] Evaluation against the five Nantes criteria ^[2].
• [ ] An image-guided diagnostic nerve block ^[5].
• [ ] (Optional) MR neurography to rule out other structural issues ^[10].

Once a diagnosis is confirmed, you can proceed to create a structured plan as outlined in Treatment Strategies: From Conservative to Surgical Care.