Early symptoms of ankylosing spondylitis are very like those of many other conditions that cause pain in the lower back. In teenagers, it is often mistaken for a sports injury. It may be years before a diagnosis of ankylosing spondylitis is considered.
- The first step in the diagnosis of ankylosing spondylitis is to take a thorough history of symptoms and make a physical examination. The doctor may check for tenderness over the sacroiliac joint. The doctor may check range of motion in the lower back and in the entire spine, and may also measure the ability to expand the chest.
- An x-ray of the pelvis can show inflammation or fusion of the sacroiliac joint and bony overgrowth or fusion of the spine.
- Magnetic resonance imaging (MRI) or computed tomography (CT) scan of the back may show early effects of the disease on the sacroiliac joint and vertebrae.
- Blood tests may be done to look for evidence of inflammation. Low-grade anemia (a lack of enough red blood cells or hemoglobin, which is the protein that carries oxygen in the blood) is also an indicator of chronic disease.
- Tests are sometimes done to check for HLA-B27 when the diagnosis is in doubt. Generally, however, presence of HLA-B27 is useless as a diagnostic indicator, as many people with back pain of other causes may also have this gene.
For further information about MRI, see MRI.
For further information about CT Scan, see CT Scan.