After reviewing your history, your health-care provider will perform a physical examination. Depending on your symptoms and the results of your physical examination, your health care provider may suggest that you undergo certain diagnostic tests.
Diagnostic tests are ordered immediately if your history or physical exam suggests significant spinal cord compression, infection or another potentially serious condition. Most people with low back pain soon return to a normal state of health, and there is usually no need for testing. If your pain is not improving or new symptoms of weakness or numbness develop, then further testing may help guide a change in your care.
Findings on your physical examination that would lead to further tests include fever, pain when your health care provider taps over your vertebrae (suggesting an infection) and evidence of nerve problems, such as numbness, weakness or abnormal reflexes. One simple way to see if the nerves near the spine are irritated is the “straight leg raise” test. In this test, your health care provider will raise your relaxed, extended leg. If this maneuver causes sudden back pain or pain that spreads from the back down the leg, you may have a disk pressing on a nerve on that side.
Although this low-tech test is revealing in certain cases, remember that each person’s back pain is unique. Your health care provider may need to order more sophisticated tests. Additional tests could include any of the following:
- Blood Tests White blood cell count — An elevated cell count can indicate infection. Erythrocyte sedimentation rate (ESR) — This test measures inflammation in the body. The ESR may be elevated if you have an infection or certain forms of arthritis. Protein analysis — An abnormal level of certain proteins in the blood can indicate a type of cancer called myeloma, a rare cause of back pain.
- Urine Tests Tests for blood in the urine may reveal findings that indicate a kidney stone or another problem in the urinary system.
- Neurophysiologic Tests The two tests used most often are nerve conduction studies and electromyography. These tests measure how nerves and muscles are functioning. Neurophysiologic tests are especially good at revealing nerve irritation, as may occur in disk disease or sciatica.
- Imaging Tests X-rays — X-rays can show if the vertebrae are lined up normally or if the vertebrae have slipped forward or back (a condition called spondylolisthesis). X-rays also can reveal evidence of arthritis or other bone abnormalities. Occasionally, X-rays of the back will detect a fracture, cancer or infection. Computed tomography (CT) — CT is a type of X-ray test that can provide a more detailed look at the lumbar spine than can conventional X-ray. CT is particularly helpful for showing problems with bones, such as arthritis or some types of spinal stenosis. Magnetic resonance imaging (MRI) — MRI can produce a highly detailed image of the lower back that provides an excellent view of the soft tissues, such as the spinal cord, disks and nerves, as well as the bones. MRI is also good at showing tumors and disk disease. Bone scan — In this test, a radioactive material called a tracer is injected into an arm vein and travels to areas of the skeleton where there may be an infection, tumor or arthritis. A special camera that can see the tracer will show these problem areas.
None of these tests is perfect. In some people, the tests may find abnormalities that have nothing to do with their pain, whereas in others, the tests show nothing out of the ordinary, despite the presence of severe back pain. Thus, both you and your health-care provider have to be careful about which tests are ordered and how you interpret the results of these tests. Still, testing is particularly helpful if your health care provider suspects a life-threatening cause of pain, because serious diseases tend to produce test results that reveal dramatic abnormalities, and getting a diagnosis quickly is critical for dangerous causes of back pain.
Why Getting A Diagnosis Is Not Always Helpful
Except in the case of life-threatening diagnoses, such as cancer and infection, treatment options for the various causes of back pain are often similar, especially when you’ve had symptoms for only a short time. For this reason, identifying a cause of pain is not always as helpful as it may seem. In addition, most back pain has no identifiable cause, so focusing entirely on establishing a diagnosis is often a frustrating experience with little impact on care.
On the other hand, there is some degree of comfort in knowing the cause of your pain or knowing that nothing dangerous is going on; uncertainty can be unsettling. For each person, an important goal of assessment is to achieve some certainty that a life-threatening condition has not been overlooked and that the recommended treatment approach is appropriate for your low back pain.