A discogram, also called a discography or provocative discography, is a diagnostic injection test used to confirm a disc as the cause of back pain. Discograms are most commonly performed in the lower back, but the procedure itself is rarely used.
An MRI or CT/myelogram scan is usually required prior to a discogram test to identify which disc(s) may be causing back pain.
How a Discogram Works
During a discogram, the patient is awake and alert so they can report any pain or pressure experienced from the injection. The test is performed on a surgical table under fluoroscopic guidance to ensure the needle is accurately placed.
Once set up, a needle is inserted into the center of a spinal disc and radiographic contrast dye is injected. If the injection recreates the patient’s back pain, that disc is verified as the pain source (a positive result) so long as control injections at the adjacent levels do not reproduce the same pain. If the discogram causes no pain or only mild pressure, it indicates the disc is not the pain source (a negative result). Additionally, the injection may cause unfamiliar back pain the patient has not experienced; in this case, the injection may indicate a different pain source, such as an arthritic facet joint.
In some cases, local anesthetic (such as lidocaine) is used to numb the discs and minimize the pain caused by the discogram. If the injection effectively alleviates the patient’s back pain, it indicates that the disc is the pain source.
Afterwards, CT scans are taken of the injected discs to provide an image of any tears or ruptures in the outer layer of the discs (called the annulus fibrosis).
When a Discogram May Be Used
A discogram is primarily used to confirm that a single disc is the pain source. This test is also used to qualify back pain patients as candidates for a spinal fusion or disc replacement surgery, as well as to plan spinal surgeries.
A discogram is a controversial diagnostic tool due to the pain caused during the injection and the relative risks associated with injections compared to an imaging study. In some cases, the needle puncture in discography may significantly increase the risk of a new disc herniation at the level tested.