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Ankylosing spondylitis (AS) can be hard to diagnose. There is no one definitive test that results in an AS diagnosis. And, because people with AS often think their back pain is “mechanical”—the kind caused by physical strain to the back—instead of chronic and inflammatory, their AS can go undiagnosed for a long time.

physical examination for ankylosing spondylitis
x-ray imaging test for ankylosing spondylitis
medical test for as

Diagnosing ankylosing spondylitis involves:

  • A physical examination of your joints and spine to look for signs of ankylosis (fusion) of the
    spine—also known as “bamboo spine.” Your doctor may:
    • Test your range of motion
    • Ask you to take a deep breath to check for difficulty expanding your chest
  • Imaging tests, which may include:
    • X-rays of your joints and bones
    • An MRI, which uses radio waves and a strong magnetic field to provide detailed images of bones and soft tissues
  • Individual medical history
  • Family history of ankylosing spondylitis
  • Blood work to test for a genetic marker called HLA-B27

While having the HLA-B27 gene doesn’t mean you have AS, it can be an important clue. Many people have the HLA-B27 gene and don’t have AS.

Why see a rheumatologist?

The most qualified person to diagnose ankylosing spondylitis is a rheumatologist. Rheumatologists are doctors who are specially trained to diagnose and treat inflammatory diseases like AS. Talk to your doctor to find out if you should see a rheumatologist.

Mechanical vs inflammatory back pain


Usually caused by physical strain to the back (eg, a sprain or muscle pull)

Typically recognized by pain that:

  • Lasts a few weeks
  • Feels better with rest
  • Can begin suddenly


Caused by the immune system attacking healthy tissue, resulting in inflammation in the joints of the spine

Typically recognized by pain that:

  • Lasts longer than 3 months
  • Feels better with exercise
  • Worsens and spreads to other areas of the body over time

Talk to your doctor if you’re experiencing any of the symptoms in the table above. Only your doctor can diagnose the type of back pain you’re suffering from.



If you have any of the following problems in addition to back pain and stiffness, they could be helpful for your doctor to know when ruling out or diagnosing AS.

Family history of AS

History of uveitis or iritis
(inflammation of the eye)

Frequent gastrointestinal issues

Itchy, flaky skin rashes

ankylosing spondylitis symptoms quiz


Find out if your back or neck pain and stiffness could be ankylosing spondylitis and then talk to your doctor about your symptoms.

rheumatologist for ankylosing spondylitis


If you have AS symptoms, talk to your doctor, who may refer you to a rheumatologist.