The following investigations are advised to support the diagnosis:

  • Blood tests
    • ESR is usually raised.
    • Hemoglobin may be low.
    • Rheumatoid Factor is negative.
  • Tissue typing: It gives corroborative evidence as presence of HLA-B27 is seen in 90% of people with this disease.
  • X-ray may show bone erosion, sclerosis, ‘squaring’ of vertebra and in later stages, the typical ‘Bamboo spine’.
  • CT scan and MRI: The early abnormality of the sacroiliac joint that may not be visible in plain X-rays can be detected by CT scan and MRI.
  • Radionuclide Imaging: It may detect the progress of the disease at the sacroiliac joint or vertebral junction in its early stage by increased uptake of radio isotopes (but it is not specific for this disease).