Ankylosing spondylitis (AS) can be difficult to diagnose because the condition develops slowly and there's no definitive test.

The first thing you should do if you think you have AS is to see your GP. They'll ask about your symptoms, including:

  • what symptoms you're experiencing
  • when they started
  • how long you've had them

Back pain associated withAS can bequite distinctive. For example, it usually doesn't improve with rest and may wake you up during the night.

Blood tests

If your GP suspects AS, they may arrange Blood tests to check for signs of inflammation in your body.Inflammation in your spine and joints is one of the main symptoms of the condition.

If yourresultssuggest you do have inflammation, you'll be referred to a rheumatologist for further tests. A rheumatologist is a specialist in conditions that affect muscles and joints.

Further tests

Your rheumatologist will carry out imaging tests to examine the appearance of your spine and pelvis, as well as further blood tests.

These may include:

  • an X-ray
  • a magnetic resonance imaging (MRI) scan
  • an ultrasound scan

Genetic testing

A genetic blood testmay sometimesbe carried out to see if you carry theHLA-B27 gene, which is found in most people with AS.

This can contribute towards a diagnosis of AS, but it's not entirely reliable as not everyone withthe conditionhas this gene and some people have the gene without ever developing AS.

Confirming ankylosing spondylitis

Although scans can sometimes show spinal inflammation and fusing of the spine (ankylosis), damage to the spine can't always be picked up in the early stages of AS.

This is whydiagnosis is often difficult. In many cases confirming a diagnosis is a long process that can take years.

A diagnosis of AS canusuallybe confirmed if an X-ray shows inflammation of the sacroiliac joints (sacroiliitis) and you have at least one of the following:

  • at least three months of lower back pain that gets better with exercise and doesn't improve with rest
  • limited movement in your lower back (lumbar spine)
  • limited chest expansion comparedwith what is expected for your age and sex

If you have all three of these features but don't have sacroiliitisor if you only have sacroiliitisyou'll be diagnosed with probable ankylosing spondylitis.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 22 Jul 2016