From the Research
Reactive arthritis is diagnosed based on a combination of clinical features, including evidence of preceding infection, asymmetric oligoarthritis of larger joints, and extra-articular manifestations, as there is no single definitive test. The diagnosis typically requires evidence of preceding infection (usually genitourinary or gastrointestinal) within the previous 1-4 weeks, followed by development of an acute, asymmetric inflammatory arthritis predominantly affecting the lower limbs 1.
Key Diagnostic Features
- Evidence of preceding infection, such as positive cultures or serology
- Asymmetric oligoarthritis of larger joints, developing within 2-4 weeks of the preceding infection 2, 3
- Extra-articular manifestations, including conjunctivitis, urethritis, and enthesitis
- Elevated inflammatory markers, such as ESR and CRP
- Negative rheumatoid factor and anti-CCP antibodies
- HLA-B27 positivity, present in 50-80% of cases, which increases diagnostic suspicion but is not required for diagnosis
Diagnostic Approach
The diagnosis of reactive arthritis remains clinical, requiring exclusion of other causes of inflammatory arthritis, such as septic arthritis, crystal arthropathies, and other spondyloarthropathies 4. A history of preceding infection, asymmetric oligoarthritis of the lower limbs, and extra-articular manifestations are the cornerstone features that establish the diagnosis.
Laboratory and Imaging Findings
Laboratory findings that support the diagnosis include elevated inflammatory markers, negative rheumatoid factor and anti-CCP antibodies, and evidence of triggering infection, such as positive cultures or serology 5. Synovial fluid analysis typically shows inflammatory characteristics with predominant neutrophils. Imaging may reveal enthesitis, sacroiliitis, or periostitis.
Importance of Early Diagnosis
Prompt recognition of reactive arthritis is key to early intervention and a better patient outcome with fewer complications 1. Without proper management, reactive arthritis can progress to a chronic destructive arthritis.