A discogram is an invasive diagnostic test that uses x-rays to examine the intervertebral discs of your spine. A special dye is injected into the injured disc or series of discs. The dye makes the disc visible on a fluoroscope monitor and x-ray film. Discograms are used to locate precisely which discs are damaged and causing the patients pain.
How Does It Work?
Discograms enable your doctor to view the disc itself. While viewing a fluoroscope (continuous x-ray imaging), the doctor inserts the needle through your skin into the center of the disc space. Once the needle is in place, a dye (contrast agent) is injected into the disc that shows up on the x-ray imaging.
A discogram works in two ways: both to view your disc and to find the source of your pain. The doctor injects the dye into the disc space to try and recreate the pain/symptoms the patient is having. If pain is felt, then that disc is likely the source of pain. If its not the same kind of pain/symptoms patient presents with, then other possible causes of your pain should be explored.
What Does It Show?
A discogram is used to evaluate a painful or degenerative disc. If the contrast dye spreads outside the center of the disc, it may indicate that the disc annulus has tears or has ruptured. The results of a discogram may confirm the need for surgery, as well as determine the exact cause of your pain, which will increase the likelihood of a positive outcome from surgery.
Prior to the injection, the patient will take an antibiotic as prescribed by the physician to decrease risk of infection. You will lie on your stomach and side during the test. After being sterilely prepped and draped, the skin over the treatment site is cleansed and numbed by injecting a local anesthetic.
Using fluoroscopy, the radiologist guides a needle into the disc or discs that will be examined. When the needles are in the correct place, the dye is injected. This will recreate the pain symptoms you have been experiencing or will intensify the symptoms you currently have. You will be asked if the pain is related to your everyday pain and symptoms with each disc injected. Lastly, the needles are removed and x-rays are taken. Most people also have a CT scan taken afterward.
The Role of Medical Imaging in Spinal Injections
Spinal injections are almost always performed under the guidance of fluoroscopy (live x-ray) or ultrasound. A contrast dye is injected into the tissues to make sure the needle is accurately placed at the suspected site of pain. Medical imaging also helps prevent injury and further complications that may be caused by injecting into adjacent structures such as blood vessels.
Therapeutic injections using fluoroscopic guidance may not be given during pregnancy or when an infection or bleeding disorder is present.