Diagnosis of Ankylosing Spondylitis: Exams and Tests

if you experience low back pain that lasts three months or more, you may have a type of axial spondylitis (axial SpA) called ankylosing spondyloarthritis (WHAT). AS is an aggressive autoimmune condition, so getting an early diagnosis and starting treatment right away is crucial.

Tests used to diagnose ankylosing spondylitis include a physical exam, medical history, blood tests, genetic testing, and imaging.

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AD symptoms usually begin in the late teens to mid-30s, but anyone can develop them, including children. But because the symptoms start slowly, they are often ignored or mistaken for other health problems. A 2015 report found that the average delay in diagnosis of axial SpA is eight years.

It is not unusual for people with AS to see multiple health care providers to manage back pain and stiffness resulting from AS. These medical professionals may include primary care providers, orthopedists (specialists in conditions of the musculoskeletal system), physical therapists, and chiropractors.

But the type of health care provider who can best diagnose AS is a rheumatologist—a physician with specialized training in musculoskeletal and Autoimmune diseases What. If you have symptoms suggestive of AS, make an appointment to see a rheumatologist or ask for a referral to your primary care provider.

This article covers tests to diagnose AS, including physical and neurological exams, blood tests, genetic testing, and imaging.

Ankylosing spondylitis physical exam

A physical exam for AS usually begins with a thorough review of your medical and family history.

Your medical history discusses whether your back pain is mechanical or inflammatory. According to the Spondylitis Association of America, mechanical back pain occurs due to physical changes in the back. It is often the result of everyday activities such as heavy lifting, incorrect posture, or poor sleeping positions.

On the other hand, AD-related inflammatory back pain is persistent, lasts for more than three months, affects people under the age of 35, and worsens after periods of inactivity. Inflammatory back pain will improve with movement, exercise, and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.

In addition to understanding the nature of your back pain, your health care provider will want to know when your symptoms started and what makes them worse and better. They also want to know about systemic symptoms (those that affect the whole body) and other joint pain in the neck, hips, shoulders, arms, and legs.

It is helpful to share all the details about your symptoms and general health to help the health care provider make an accurate diagnosis.

the HLA-B27 gene, which can lead to AS, is inherited. Furthermore, family and twin studies have shown that AS has a strong genetic component. You should tell your healthcare provider if AD or other autoimmune diseases run in your family.

Once the health care provider has obtained information about your medical and family history, he or she will want to perform a complete physical and neurological examination.

You will be asked to bend your back and hips in different directions during the physical exam to check for stiffness and pain. They may also press on areas of the body to look for tender spots.

Since shortness of breath is a sign of severe AS, your health care provider will also monitor your breathing. Respiratory problems in AS result from scarring of the lungs due to inflammation, a forward-arched upper body, and chest wall stiffness.

The neurological exam assesses sensory and motor functions, including reflexes and muscle strength. Your health care provider will also review your other neurological symptoms, such as nerve pain, numbness, tingling, muscle weakness or spasms, and bowel and bladder dysfunction.

Blood tests for ankylosing spondylitis

Blood tests can look for signs of inflammation suggestive of AS. It is also done to rule out other conditions. Blood tests are not enough to confirm AS, but they do help your healthcare provider understand your symptoms.

There are no specific tests to confirm AS, but certain blood tests can detect inflammatory markers and rule out other conditions that cause similar symptoms.

The following blood tests may be ordered if AS is suspected:

  • erythrocyte sedimentation rate (ESR or Sedimentation Rate): The ESR test detects inflammation in the body. The ESR rate is measured by how quickly red blood cells settle in a test tube.
  • C-reactive protein (CRP): CRP is a protein produced by the liver. High CRP levels are an indication of a condition that causes inflammation.
  • Complete blood count (CBC): The CBC test checks blood cell counts. High white blood cell counts and low red blood cell counts indicate inflammation commonly associated with AS.
  • rheumatoid factor (RF): RF is often associated with other autoimmune arthritis conditions such as Rheumatoid arthritis Y lupus. RF testing is ordered to rule out these conditions when AS is suspected.

Genetic testing for ankylosing spondylitis

A genetic blood test may be ordered to see if you carry the HLA-B27 gene. According to a 2018 report, this gene is only found in 8% of the general population. HLA-B27 is present in 90% of people with AS.

A positive test for HLA-B27 does not mean that you will develop AS. Only about 5% to 6% of people with the gene will develop AS, according to a 2019 report in the newspaper bone research.

If you carry the HLA-B27 gene, your healthcare provider is more likely to suspect AS. This gene is also linked to more severe AD symptoms, such as eye inflammation and a condition called uveitis (inflammation of the middle layer of tissue in the wall of the eye).

Imaging tests for ankylosing spondylitis

Different imaging studies can help make a diagnosis of AS, including conventional radiology (X-rays), magnetic resonance imaging (magnetic resonance), computed tomography (CT) and ultrasound. X-rays are standard to diagnose AS, while a CT scan, MRI, or ultrasound may be ordered to evaluate the bones and soft tissues of the spine in more detail.

If your healthcare provider requests imaging, they may be looking for the following signs of AS:

  • sacroiliitis (inflammation of one or both SI joints)
  • waste of cartilage in the facet joints (located between the vertebrae), which can lead to fusion
  • Loss of normal spinal curvature leading to kyphosis (hunchbacked) or lordosis (Influenced)
  • Spinal and pelvic fractures
  • Bone erosion (bone loss) in the lower back
  • Bony growths on the vertebrae
  • Calcification (hardening of the bones)

Your health care provider may use X-rays and MRIs to track the progression of AS disease or to look for fractures or joint damage.

Confirming a diagnosis of ankylosing spondylitis

Your health care provider will use your physical and neurological exams, history of symptoms, imaging results, and blood tests to diagnose AS.

According to a 2020 Rheumatology report, a health care provider can make a diagnosis of AS based on specific criteria, including:

  • Back symptoms: this includes back pain that has lasted for three or months and started before the age of 40 that resolves with exercise and is worse in the morning and after periods of inactivity, back pain that alternates with pain in the buttocks and limited movement of the lower back.
  • Finding relief with NSAIDs, indicating that back pain is the result of inflammation
  • Peripheral manifestations, such as arthritis in the arms, legs, and shoulders, dactylitis (swelling of the fingers and toes), and enthesitis (inflammation of the entheses, the sites where tendons and ligaments attach to bone)
  • Extramusculoskeletal manifestations, such as uveitis, psoriasis (a chronic skin condition), and Inflammatory bowel disease
  • Positive family history of AS
  • HLA-B27 positivity
  • High levels of CRP and ESR
  • Imaging evidence of sacroiliitis
  • Osteitis (bone inflammation) and/or bone marrow edema (fluid buildup in the bone marrow), which can be seen on an MRI

If you have experienced inflammatory back pain for at least three months or more, along with other features that are part of the diagnostic criteria for AS, your health care provider will likely diagnose you with AS.


Ankylosing spondylitis is an autoimmune disease that occurs when the immune system malfunctions and attacks healthy tissue, primarily the small bones of the spine. AS is an aggressive condition and early diagnosis is crucial to reduce spinal complications such as spinal fusion, fractures, and abnormal curvatures.

If you experience signs and symptoms of AS, such as pain and stiffness in your lower back and hips, contact a health care provider so that tests can be ordered to determine the cause. Tests used to diagnose AS include physical and neurological exams, blood tests, genetic testing, and imaging.

AD diagnosis is usually based on symptoms, blood tests, imaging results, and HLA-B27 positivity.

A word from Verywell

Ankylosing spondylitis is a lifelong condition. There is no cure for the disease, but it is treatable and manageable.

You will have many options to treat your condition that can reduce symptoms and prevent disease progression. Taking your medications as prescribed is crucial to lessening the effects of the disease on you, keeping you mobile and independent, and maintaining a good quality of life.

In addition to following your treatment plan, you should see a rheumatologist regularly. And be sure to speak up if your treatment plan isn’t managing your symptoms adequately.

Frequent questions

  • What are the early warning signs of ankylosing spondylitis?

    The first signs of ankylosing spondylitis are pain and stiffness in the lower back and hips, especially in the morning and after periods of inactivity. You may also experience neck pain and fatigue. Over time, these symptoms will worsen or improve during flares (worsening of the disease) and remission (absence of symptoms).

  • Do you need to see a specialist for ankylosing spondylitis test?

    If you are experiencing symptoms of ankylosing spondylitis, a primary care provider may refer you to a rheumatologist. A rheumatologist is specially trained to diagnose and treat disorders such as AD that affect the joints, muscles, connective tissues, and bones.

  • What happens after being diagnosed with ankylosing spondylitis?

    After you’ve been diagnosed with ankylosing spondylitis, you’ll want to work with your health care provider to create a treatment plan. You will be prescribed medications and information on lifestyle habits to help manage symptoms, such as diet changes, exercise, and adaptive aids to reduce stress on your joints.

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