The value of synovial fluid assays in the diagnosis of joint disease: a literature survey

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ls of the Rheumatic Diseases 2002;61:493-498

The value of synovial fluid assays in the diagnosis of joint disease: a

literature survey

A Swan1, H Amer2 and P Dieppe2

1 Division of Medicine, University of Bristol

2 MRC Health Services Research Collaboration, Department of Social

Medicine, University of Bristol

Correspondence to:

Dr A Swan, MRC/ARC Synovial Fluid Crystal Project, Department of

Veterinary Anatomy, University of Bristol, Southwell St, Bristol BS2

8EJ, UK;

.Swan@...

Objective: To carry out a critical appraisal of the literature in an

attempt to assess the current value of synovial fluid (SF) analysis in

the diagnosis of joint disease.

Methods: A literature search was undertaken using the Medline, Biomed,

Bids, Pubmed, and Embase electronic databases using the keywords:

synovial fluid (SF) analysis, SF crystals, joint sepsis, acute

arthritis, and SF cell counts, cytology, biomarkers, and microbiology.

Results: Publications fell into three main categories. Firstly, reports

assessing the value of the three traditional assays (microbiology, white

blood cell counts, and microscopy for pathogenic crystals). For these

quality control evidence was found to be sparse, and tests for

sensitivity, specificity, and reliability showed worrying variations.

These poor standards in SF analysis may be due to lack of inclusion of

some tests within routine pathology services. Secondly, claims for the

usefulness of " new " assays (cytology and biochemical markers). For

cytology, the supporting evidence was mainly anecdotal and there were no

reports on specificity, sensitivity, and reliability. Interpretation

difficulties are a major hindrance to the clinical use of biochemical

assays, which remain primarily research tools. Finally, work on the

diagnostic value of SF analysis in general. The appraisal confirmed that

SF analysis remains of major diagnostic value in acute arthritis, where

septic arthritis or crystal arthropathy is suspected, and in

intercritical gout.

Conclusions: Given the importance of SF tests, rationalisation of their

use, together with improved quality control, should be immediate

priorities. Further investigation is recommended into the contribution

of SF inspection and white cell counts to diagnosis, as well as of the

specificity and sensitivity of SF microbiological assays, crystal

identification, and cytology.