How is ankylosing spondylitis (AS) diagnosed?
The diagnosis is typically suspected by the doctor based on the signs and symptoms. The doctor will take a thorough history and do a physical examination. X-rays, especially those of the sacroiliac joints and spine can be confirmatory. The HLA B27 gene may be checked by a blood test, but its presence or absence does not ultimately confirm or reject the diagnosis.
How is reactive arthritis diagnosed?
The diagnosis is typically made by a doctor taking a thorough history and physical examination. A swollen joint may be aspirated to rule out an infection or gout. There is no specific test for the diagnosis of ReA. The HLA B27 gene may be checked by blood test in selected cases, but it is not diagnostic.