What is a ganglion impar block?

A ganglion impar block is a type of shot (injection) that eases pain. It’s used for a variety of health problems that cause pain in the lower pelvis and groin.

Your brain sends information to the body through pathways called nerves. Nerves also receive information from the body and send it to the correct regions of the brain. A ganglion is a place in the body where many nerves come together and cross. Nerves that communicate some types of pain from the lower pelvis and groin pass through the ganglion impar on their way to the brain.

The ganglion impar sits just in front of your sacrum. The sacrum is the lowest part of the spine. It's just above the tailbone (coccyx). Nerves from some parts of the lower pelvis and groin pass through this ganglion, including nerves from:

  • Lower part of the rectum
  • Anal region
  • Lower part of the urethra
  • Vagina and vulva
  • Scrotum
  • Perineum. This is the area from the anus to the vagina or base of the testicles.
  • Tailbone

During a ganglion impar block, your healthcare provider will put a needle into the area near your tailbone between your buttocks. They will then move it to a position just in front of the sacrum. That’s where the ganglion impar is. Medicine to help block pain signals in the area will then be injected.

Why might I need a ganglion impar block?

A ganglion impar block might be needed if you have lower pelvic or groin pain caused by dysfunction or damage to organs in the area. Your healthcare provider may advise it if you have tried other ways to control the pain, but your pain is still not manageable. For instance, a ganglion impar block might help you if you have:

  • Vaginal or vulvar cancer
  • Scrotal cancer
  • Rectal or anal cancer
  • Bladder cancer
  • Pain in the tailbone
  • Rectal pain, or pain from other close structures

In some cases, your healthcare provider might use a ganglion impar block to diagnose the cause of your pain. They can inject a numbing medicine (local anesthetic) in the area to see if your pain lessens. Doing so may help pinpoint the source of pain. In other cases, your provider might use a ganglion impar block to treat your pain with other medicines. Less commonly, the procedure might help with other problems, such as excess sweating in the anal region.

What are the risks of a ganglion impar block?

Ganglion impar block is generally very safe. Some rare risks of the procedure are:

  • Damage to nearby organs
  • Bleeding
  • Infection
  • Allergic reaction to the medicine or medicines

If you get a steroid shot, you may have some side effects. These include short-term (temporary) increases in blood sugar levels for 1 to 2 days, an allergic reaction, and flushing on your face. There is also a risk that the procedure will not ease your pain.

You may not be able to have the procedure if you have a high risk of bleeding. That may also be true if you have an infection in the area of the injection. Your own risk may vary based on your age and any other health problems. Before the procedure, talk with your healthcare provider about all your concerns.

How do I get ready for a ganglion impar block?

Talk with your healthcare provider about your past health. Let them know if you have an infection, fever, or other recent health problems. If you have diabetes or use any blood-thinning medicines, check if you need to take any special precautions.

You should also discuss all your medicines with your healthcare provider. That includes over-the-counter medicines. You may need to stop taking certain medicines a few days before the shot. Also be sure to tell your provider if you:

  • Have any allergies
  • Have had any problems with contrast dyes, past injection procedures, anesthesia, or other medicines
  • Are pregnant, breastfeeding, or might be pregnant

Follow any directions you are given for not eating or drinking before surgery.

You may get medicine to help you relax during the injection. You should arrange to have someone drive you home afterward. Your provider may give you other directions about how to prepare.

What happens during a ganglion impar block?

Ask your healthcare provider about what to expect. Your exact procedure may differ. But general steps for a ganglion impar block are the following:

  • You will lie down on your stomach on a procedure table.
  • You may get medicine to help you relax (sedation). But you will likely remain awake during the procedure.
  • During the procedure, your heart rate, blood pressure, and oxygen level will be closely watched. You may get extra oxygen by a mask or nasal tubing.
  • The area where you will have the shot will be cleaned.
  • The healthcare provider will give you medicine to numb the skin around the injection area. It may burn and sting a little. But it should last only a few seconds.
  • The provider will insert a needle into the area around your tailbone between your buttocks. They will advance the needle until it is in the area of the ganglion impar. They may use X-rays, CT imaging, or ultrasound to help guide the needle. The provider will inject a small amount of X-ray contrast dye through the needle to make sure it's in exactly the right spot.
  • The provider will then inject medicine through the needle. They might use different types of medicine for different reasons. Numbing medicine may be needed to block pain. A steroid may be used to reduce inflammation. In some cases, the provider may use other medicines to temporarily damage the nerves. That stops them from sending pain signals. After the medicine is injected, you may feel a warm or burning sensation in the area.

What happens after a ganglion impar block?

Generally, you will be watched for 30 to 60 minutes after the procedure. Make sure someone can drive you home. You should not plan to do anything strenuous or anything that calls for your full attention for the rest of the day.

Ask your healthcare provider about any activity restrictions after the procedure. You should be able to eat and drink normally. Ask when you should resume your normal medicines. Make sure to follow all your provider’s directions for care.

It's common to have some pain at the injection site for a few days. Many people feel relief from their pain soon after the procedure. This relief might last a few hours, a few weeks, or longer depending on the medicine used.

Call your healthcare provider if you have any of these symptoms:

  • Severe pain
  • Weakness or numbness in the legs
  • Changes in bowel or bladder function
  • Fever
  • Bleeding at the injection site
  • Signs of infection at the injection site. These include redness, swelling, and oozing.

Your healthcare provider can tell you more about what you should do and what you can expect after the ganglion impar block. You will need to follow up with your provider to talk about the effects of the procedure and make a plan for future treatment of your pain.

Next steps

Before you agree to the test or procedure make sure you know:

  • The name of the test or procedure
  • The reason you are having the test or procedure
  • What results to expect and what they mean
  • The risks and benefits of the test or procedure
  • What the possible side effects or complications are
  • When and where you are to have the test or procedure
  • Who will do the test or procedure and what that person’s qualifications are
  • What would happen if you did not have the test or procedure
  • Any alternative tests or procedures to think about
  • When and how will you get the results Who to call after the test or procedure if you have questions or problems
  • How much will you have to pay for the test or procedure