Synovial Fluid Culture
Aerobic and anaerobic culture to determine identity and
susceptibility of organisms. Cultures are held for seven (7) days on
all samples and 14 days for shoulder specimens.
White Blood Cell (WBC) Count w/ Differential
Automated, high-performance cell count that provides overall number
of white blood cells and percentage breakdown of white blood cell
(WBC) type in synovial fluid.
A 2020 study shows that automated WBC count can be affected by the
presence of a total joint arthroplasty, leading to higher rates of
false-positive results.12 All WBC counts >3,000
cells/ul are confirmed by a manual count.
Crystal Analysis
Polarized microscopy to detect monosodium urate (MSU) and calcium
pyrophosphate dihydrate (CPPD) crystals to aid in identifying the
presence of gout and CPPD disease (pseudogout).
Synovial Fluid C-Reactive Protein (CRP)
The Synovial Fluid CRP test measures the levels of the c-reactive
protein biomarker within a specimen.
A 2024 clinical study10 demonstrated 86.1% Sensitivity
and 87.1% Specificity compared to the 2018 ICM Definition of PJI,
outperforming published Serum CRP diagnostic performance.