The preservation of synovial fluid using dimethyl sulfoxide

Background: The Royal College of Pathologists of Australasia Quality Assurance Programs runs a Quality Assurance Program for the assessment of synovial fluid crystals. It provides aliquots of synovial fluid to various laboratories. The quality of specimens can deteriorate prior to being examined. We aimed to assess whether the addition of dimethyl sulfoxide (DMSO) to synovial fluid specimens helps maintain cellular morphology.

Methods: Synovial fluid specimens were obtained from 15 patients. Each specimen was aliquoted into 24 samples, with half having DMSO added at a concentration of 10%. For each specimen, six samples containing DMSO and six samples not containing DMSO were stored at-80°C and room temperature. Samples from each group were examined at 1, 2, 3, 6, 7 and 8 weeks. Comparative Analysis: For each specimen, the final remaining aliquoted samples containing DMSO and not containing DMSO, which were stored at-80°C, were directly compared. Quantitative Analysis: A system for grading cellular morphology and assessing for artefacts and cellular clumping was applied by two independent assessors.

Results: Comparative Analysis: A significant difference was found between samples containing DMSO and not containing DMSO which were stored at -80°C (p = .000), in favour of those containing DMSO. Quantitative Analysis: Regarding the combined findings of Assessors 1 and 2 and the grading of cellular morphology, a significant difference was found according to "groups" (p = .000), in favour of those containing DMSO and stored at-80°C.

Conclusions: DMSO contributes to the maintenance of cellular morphology in synovial fluid when stored in frozen conditions.