Undifferentiated spondyloarthritis

The term undifferentiated spondyloarthritis (USpA) may be soon become of historic interest only. The term USpA was introduced to classify patients who did not fit into a specific definition of SpA like AS, psoriatic spondylitis, IBD associate SpA and juvenile SpA.

These patients, over time, may progress to AS or develop psoriasis or IBD and thus re-categorize into those entities. However, as the new classification system of axial and peripheral SpA may encompass most patients with SpA, there are very few patients who are classified as USpA now.

Symptoms of undifferentiated spondyloarthritis (USpA)

  • Back pain
  • Enthesitis
  • Pain and swelling in the fingers or toes
  • Buttock pain on one or both sides
  • Heel pain
  • Iritis
  • Tiredness and fatigue

Diagnosis of undifferentiated spondyloarthritis (USpA)

A rheumatologist is best placed to diagnose undifferentiated spondyloarthritis. Diagnosis can be very difficult and is usually based on clinical impression. Gene testing for HLA-B27 and X-rays for sacroiliitis may not be helpful.


Learn about the management of undifferentiated spondyloarthritis (USpA).