A discogram, or diskogram, is a test used to evaluate back pain. A discogram may help your doctor determine if your back pain could be caused by an abnormal disk in your spine. Spinal disks look a little like jelly doughnuts, with a tough outer layer and a gel-like substance inside. Disks act as cushions between the vertebrae in your spine.

During a discogram, dye is injected into the soft center of the disk. The injection itself sometimes reproduces your back pain. Several disks may be injected, to try to pinpoint the cause of your back pain. In addition, the dye will move into any cracks in the disk's exterior and will show up on an X-ray or CT scan. But cracked disks don't always cause symptoms, so the usefulness of a discogram is controversial.

Because it's an invasive test, a discogram isn't appropriate for an initial evaluation of back pain. But your doctor may suggest a discogram if your back pain persists despite conservative treatments, such as medication and physical therapy.

Some doctors use a discogram before spinal fusion surgery, to help identify which disks need to be removed. However, discograms are not always accurate in pinpointing which disks, if any, are causing back pain. Many doctors instead rely on other tests, such as MRI and CT scanning, to diagnose disk problems and guide treatment.

A discogram is generally a safe procedure. But as with any medical procedure, a discogram carries a risk of complications. Potential complications include:

  • Infection
  • Worsening of chronic back pain
  • Headache
  • Nausea
  • Injury to blood vessels or nerves in and around the spine
  • Allergic reaction to the dye

You may need to avoid taking blood-thinning medications for a period of time before the procedure. Your doctor will give you specific instructions about what medicines you can take and if you need to avoid food or drink the morning before the test.

A discogram takes between 30 and 60 minutes, and you'll be able to go home later that same day.

During a discogram

A discogram is performed in a clinic or hospital room that has imaging equipment, so your disks can be examined during the procedure. You are awake during a discogram, but your doctor may give you an intravenous sedative to help you relax. You may also receive antibiotics to help prevent infection.

During the procedure, you lie on a table either on your stomach or on your side, rolled forward slightly. After cleaning your skin, your doctor may inject a numbing medicine to decrease pain caused by the insertion of the discography needles.

Your doctor will use fluoroscopy, an imaging technique that allows him or her to watch as the needle enters your body. This allows precise placement of the needle into the center of the disk to be examined. A contrast dye is then injected into the disk and an X-ray or CT scan is taken to see if the dye spreads.

If the dye stays in the center of the disk, the disk is normal. If the dye spreads outside the center of the disk, it means the disk is damaged. It may have begun to rupture or it may have tears in its outer ring. Typically, if a damaged disk is the source of your back pain, you feel pain during the injection that's similar to the back pain you have day to day. If a disk is normal, there's little pain during injection.

After a discogram

After a discogram, you remain in the procedure room for approximately 30 minutes to one hour for observation. Because of the sedation, have someone else drive you home following a discogram. You may have some pain at the injection site for several hours after you go home. If the pain is severe, call your doctor right away.

Your doctor will review the images taken during the discogram, along with the information you provided during the procedure about the pain you experienced. Both the images and your description of the pain are important to help determine if the disks examined are the source of your back pain. Your doctor will use this information to guide your ongoing treatment or prepare for surgery.

Because a disk can be damaged without causing pain, and because reports of pain during a discogram can vary widely — depending on your pain tolerance, your description of the pain and a variety of other factors — doctors usually don't rely on the results of a discogram alone to direct treatment. Typically, results of a discogram are combined with results of other tests — such as MRI or CT scanning and physical examination — when determining a treatment plan for back pain.

Feb. 25, 2012