Discogram Test: Purpose, Test Details & Results

Purpose of Discogram Test

Discograms, or discography, are specialized diagnostic tests designed to evaluate the integrity and pain-generating capacity of intervertebral discs in the spine. When someone suffers from persistent, unexplained back pain, pinpointing the exact source can be challenging. A discogram helps doctors determine whether a specific spinal disc is the likely source of pain, especially when other imaging tests like MRI or CT scans offer inconclusive results. This test is most commonly used for patients being considered for spinal surgery, or when more conservative treatments have failed.

Discography is unique in that it not only reveals structural disc abnormalities, but also assesses whether these abnormalities are actually causing pain. By doing so, it helps doctors and patients make more informed decisions about further treatment options, ranging from surgery to continued conservative management. However, it’s important to recognize that the interpretation of discogram results can be complex and sometimes controversial, and that the test is generally reserved for select cases where its diagnostic value can make a meaningful difference in patient care 2 3 4 7.

Table 1: Major Purposes of Discogram Testing

How Discograms Help Identify Pain Sources

Discograms are particularly valuable for differentiating between discs that are structurally abnormal but not painful, and those that are both abnormal and pain-generating 3 7. During the test, physicians inject contrast dye into one or more discs under live imaging. If the injection reproduces the patient’s typical pain, that disc is likely contributing to symptoms. In contrast, if the disc is abnormal on imaging but does not produce pain during injection, it may not be the source of discomfort 3.

When is a Discogram Recommended?

• Persistent back pain: Especially when pain persists despite physical therapy, medications, or other treatments.
• Surgical decision-making: When considering spinal fusion or other invasive procedures, discography can clarify whether surgery is likely to help 2 4 5.
• Inconclusive imaging: When MRI or CT scans show degenerative changes at multiple levels, but it’s unclear which, if any, are responsible for pain 3 7.

Considerations and Limitations

Not every patient with back pain needs a discogram. The test is best reserved for:

• Patients with a clear history and physical findings suggestive of discogenic pain.
• Those with ambiguous or multiple abnormalities on imaging.
• Individuals for whom surgery is a serious consideration.

It’s important to note that discography is not without controversy:

• Some studies suggest that discograms may accelerate disc degeneration, particularly if followed by spinal fusion surgery, though this risk appears less relevant for patients not undergoing surgery 2.
• Pain response during discography can be influenced by psychological factors, and not all pain provoked during the test correlates with real-life symptoms 6 7.

Discogram Test Details

The discogram procedure is a carefully controlled diagnostic intervention performed under sterile conditions, usually by a spine specialist or interventional radiologist. Understanding how the test is conducted, what patients experience, and how safety is maintained is essential for anyone considering or preparing for a discogram.

Table 2: Key Steps in the Discogram Procedure

Preparation and Patient Selection

Before a discogram:

• Doctors review prior imaging (MRI, CT) to identify discs of interest.
• Patients are screened for infection risk, bleeding disorders, and allergies to contrast dye or local anesthetics.
• Informed consent is obtained, and the procedure is explained, including potential risks and discomfort 2 4.

The Injection Process

• The patient lies on their stomach or side.
• After local anesthetic is applied to numb the skin and deeper tissues, a thin needle is advanced into the center of the disc under X-ray (fluoroscopic) guidance.
• A small amount of contrast dye is injected into the disc nucleus. The physician watches how the dye spreads and closely monitors the patient’s pain response 1 3 4.

Assessing the Pain Response

• The key question: Does the injected disc reproduce the patient’s familiar back pain, or is the pain response different (unfamiliar, minimal, or absent)?
• The physician often injects several discs: suspected painful discs as well as at least one "control" disc (which is not expected to be painful) 3 4 7.
• Pain is rated on a scale (commonly 0–10) and described as "familiar" (matching the usual pain) or "unfamiliar" 3 4.

Imaging and Structural Assessment

• Post-injection, X-ray or CT scan images show the pattern of dye distribution within the disc.
• These images reveal structural changes such as fissures, tears, or abnormal pooling of dye, indicating disc degeneration or annular disruption 1 3 4.
• The Dallas Discogram Scale is often used to grade the severity and type of annular tears 3.

Variations and Advanced Techniques

• Pressure-Controlled Discography: Uses manometric equipment to precisely measure injection pressure and pain threshold, improving standardization 3 7.
• Stress Discography: Performed during periods when the patient is experiencing significant pain, aiming to reproduce symptoms more reliably 4.
• Functional Anesthetic Discogram: Involves injecting a small amount of local anesthetic into the disc to see if it relieves pain during provocative positions, helping to differentiate truly symptomatic discs 7.

Risks and Safety

The discogram is generally safe when performed by experienced practitioners, but risks include:

• Temporary worsening of back pain.
• Disc infection (discitis).
• Bleeding or nerve injury (rare).
• Allergic reaction to contrast dye.

Long-term risks, such as accelerated disc degeneration, are debated but seem to be more relevant in patients who undergo subsequent spinal fusion surgery 2 6.

Discogram Test Results & Follow-Up

Discogram results are not simply “positive” or “negative.” They require careful interpretation, integrating the patient’s pain response, structural changes seen on imaging, and clinical context. Understanding what the results mean, their limitations, and what happens next is essential for patients and providers alike.

Table 3: Interpreting Discogram Results

Interpreting the Results

Positive Discogram

A disc is considered “positive” when:

• Injection provokes the patient’s typical (familiar) pain at a pressure and volume that are within defined limits.
• Imaging shows abnormal dye distribution (fissures, tears, pooling).
• Control discs do not provoke pain, helping to rule out a generalized pain response 3 4 5.

A positive discogram may support the diagnosis of discogenic back pain and influence the decision to proceed with targeted treatments, such as spinal fusion 2 4 7.

Negative Discogram

A “negative” disc means:

• No familiar pain is reproduced during the test, even if structural abnormalities are present.
• Pain scores are low, and imaging may still show degenerative changes, highlighting the importance of functional testing alongside structural analysis 3 5 6.

Negative findings can help prevent unnecessary surgeries and focus attention on alternative diagnoses or treatments.

Indeterminate or Mixed Results

Sometimes:

• Multiple discs provoke pain, or the patient reports unfamiliar pain responses.
• Psychological factors, such as heightened pain sensitivity or somatization, may influence the test, making interpretation challenging 6 7.

In these cases, further evaluation—including psychological assessment and correlation with the overall clinical picture—is essential.

Follow-Up After Discography

Impact on Treatment Planning

• Surgery: Positive discogram findings may support proceeding with spinal fusion or disc replacement at the identified level. However, outcomes are not always predictable, and surgery does not guarantee complete relief 2 5.
• Conservative Management: Negative or indeterminate discograms often prompt a reassessment of non-surgical options, including physical therapy, pain management, and psychological support 5 6.
• Patient Counseling: Results should be discussed with patients in detail, including the limitations of discography and the potential risks and benefits of subsequent interventions.

Long-Term Outcomes

• Patients with positive discograms but who do not undergo surgery often do as well—or better—than those who have surgery, especially if they lack psychiatric comorbidities and have a shorter duration of symptoms 5.
• In asymptomatic individuals, a painful discogram does not predict the future development of back pain, and structural abnormalities may have little clinical significance 6.
• Psychological factors are strong predictors of long-term outcomes, sometimes more so than discogram findings themselves 6.

Limitations and Controversies

• The accuracy of discography in identifying the true pain generator is debated, as some discs may be structurally abnormal yet not painful, and vice versa 3 7.
• Newer techniques, such as functional anesthetic discography, may improve specificity by focusing on both pain relief and pain provocation 7.
• The risk of accelerating disc degeneration appears minimal in patients not undergoing subsequent spinal fusion 2.

Conclusion

Discograms are specialized tools designed to clarify the often-complex landscape of chronic low back pain. When used in carefully selected patients and interpreted within the broader clinical context, discography can provide valuable insights that guide treatment decisions and help avoid unnecessary interventions. However, the test has limitations and should always be integrated with other clinical and imaging findings.

Key points:

• Discograms help pinpoint if a spinal disc is the true source of back pain, especially when imaging is inconclusive 1 2 3 4.
• The procedure involves injecting dye into the disc and monitoring pain responses and dye patterns on imaging 1 3 4.
• Results must be interpreted cautiously, considering pain response, structural findings, and psychological factors 3 5 6 7.
• Discograms can help guide surgery or prevent unnecessary procedures, but are not perfect predictors of outcomes 2 4 5 7.
• Long-term risks are minimal in non-surgical patients, and psychological health is a major factor in future outcomes 5 6.
• Discography is most useful when incorporated as part of a comprehensive, patient-centered approach to back pain management.