The average time from when a person first noticed symptoms of AS to a diagnosis of AS is about 8 years. That’s partly because AS can be difficult to diagnose in its early stages. Not only does AS affect people in different ways, but it also usually begins very slowly. It can also be mistaken for other forms of arthritis, especially if pain begins in the hips, knees, or shoulders. To add to these difficulties, there is currently no single test to identify the disease. Instead, diagnosis is usually based on the expert clinical evaluation of a rheumatologist.

The difficulty in diagnosing AS makes it important that you are prepared to tell your doctor about all of your symptoms. For a clinical diagnosis, your doctor will likely refer you to a rheumatologist and/or:

• Ask about your medical history;
• Consider all your symptoms;
• Perform a physical examination;
• Run some laboratory tests on a sample of your blood;
• Send you for x-rays or other diagnostic imaging tests to look for changes in your joints.