Learn more about ankylosing spondylitis and similar conditions.
Why Is Ankylosing Spondylitis Difficult to Diagnose?
Ankylosing spondylitis can be challenging to diagnose for two primary reasons:
There is no specific test for ankylosing spondylitis. The symptoms can slowly increase and worsen over time.
Even though there is no single test for ankylosing spondylitis, testing such as magnetic resonance imaging (MRI) can help to detect the condition.
Another reason ankylosing spondylitis can be challenging to diagnose is because symptoms are similar to other conditions, such as rheumatoid arthritis. However, there are differences. For example, ankylosing spondylitis generally affects the back, while rheumatoid arthritis generally affects joints such as knees, wrists, and hands on both sides of the body.
Similar Diseases to AS
Ankylosing spondylitis is a type of arthritis and is in the spondyloarthritis family.
Other types of spondyloarthritis are:
Axial spondyloarthritis Enteropathic arthritis Peripheral spondyloarthritis Psoriatic arthritis Reactive arthritis
The symptoms of ankylosing spondylitis include pain and back stiffness, challenges with posture, and fatigue, which mimic conditions with similar symptoms, including:
Fibromyalgia Psoriatic arthritis Rheumatoid arthritis
Back Pain and Injury
Injuries, diseases of the spine, and other medical conditions such as kidney stones or infections cause back pain.
Back injury such as back strain or sprain can lead to symptoms such as:
Back painDifficulty maintaining good posture Stiffness
People with ankylosing spondylitis have a higher risk of back and spinal injuries since ankylosing spondylitis can cause bones to become brittle and fused, decrease mobility, and lead to falls. Diagnosing ankylosing spondylitis is challenging if an injury seemingly causes all the symptoms.
Fibromyalgia
Fibromyalgia is a long-term medical condition common among people with ankylosing spondylitis. Much like ankylosing spondylitis, symptoms of fibromyalgia include pain and fatigue.
Additionally, many people with ankylosing spondylitis, particularly women, are misdiagnosed with fibromyalgia. One study of people with ankylosing spondylitis found that 20.7% of women received an inaccurate fibromyalgia diagnosis compared to 6.6% of men.
Psoriatic Arthritis
Like ankylosing spondylitis, psoriatic arthritis is a type of arthritis. Symptoms of psoriatic arthritis include swelling and pain in the joints (more often in fingers and toes than in the back) and usually involves a rash.
While these symptoms differ from those commonly seen with ankylosing spondylitis, psoriatic arthritis can lead to back pain and stiffness and can be confused with ankylosing spondylitis.
Rheumatoid Arthritis
As with all autoimmune diseases, rheumatoid arthritis occurs when the immune system attacks healthy cells by mistake. Symptoms include:
PainSwellingStiffnessFatigue
The overlap between the symptoms of both conditions leads people with ankylosing spondylitis to be misdiagnosed with rheumatoid arthritis.
Diffuse Idiopathic Skeletal Hyperostosis
Diffuse idiopathic skeletal hyperostosis is arthritis that affects tendons and ligaments in the back, leading to pain and stiffness.
While the symptoms are similar, the age of illness onset differs. Ankylosing spondylitis tends to begin in early adulthood. In contrast, diffuse idiopathic skeletal hyperostosis typically occurs later in life among people who have obesity or diabetes mellitus.
Sciatica
Sciatica is a condition caused by pressure or damage to the sciatic nerve. It begins in the lower back and causes pain and weakness in the leg. It is also linked to poor posture. Unlike ankylosing spondylitis, sciatica usually doesn’t require treatment beyond rest and often goes away independently.
How to Diagnose Ankylosing Spondylitis
There is no specific test to screen for or diagnose ankylosing spondylitis. Early ankylosing spondylitis diagnosis can be challenging because spinal damage cannot always be seen on imaging tests.
Ankylosing spondylitis is diagnosed by assessing health history, getting a physical exam by a medical professional, and testing that may include:
X-rays Blood tests Genetic tests
Summary
Symptoms of ankylosing spondylitis overlap with those of other medical conditions, making diagnosis challenging. Additionally, the disease can progress slowly, and no specific diagnostic tests make misdiagnosis common. If you are experiencing symptoms of ankylosing spondylitis, contact your healthcare provider to help with diagnosis and treatment options.
A Word From Verywell
Living with pain from ankylosing spondylitis is challenging, especially when you experience delays in diagnosis and treatment. Support is available if you or someone you know is experiencing symptoms of ankylosing spondylitis.
Once you receive an accurate diagnosis, your ankylosing spondylitis can be treated. Reach out to a healthcare provider such as a primary care practitioner or rheumatologist for support.
