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Synovial Fluid Analysis

Item Value
Approval req'd? No
Available Stat? Yes
Test code SSYN, SCRY
Performed by? Hematology
Price range $
In House Availability 24 hours/7 days
Principle RBC, WBC, abnormal and neoplastic cells are counted in a hemocytometer

All synovial fluids are examined under polarized light for crystals.
Container type EDTA (lavender top) tube or Sodium heparin (dark green top tube
Collection Instructions Any body fluid that might clot should be collected in an EDTA tube (lavender top) and mixed well by inversion. 1.0 to 3.0 mL is sufficient volume. Cell count will NOT be performed on a clotted specimen.

Specimen label must include date and time sample was collected and the legible name of the person who collected.

Bring sample ASAP to laboratory for testing.
Min. Volume 1 mL
Synonyms Synovial Fluid Ceel Count and Crystal Identification; Gout; Uric Acid; Pseudo gout; Calcium pyrophosphate dihydrate; CPPD; Joint Fluid;
Stability 4 hours at room temperature.
Cells may begin to deteriorate after 30 minutes.
Causes for rejection Syringes with needles still attached.

Samples collected in Lithium heparin (light green top) tube may produce false positive crystal results. Lithium heparin is not appropriate for synovial fluid analysis.

Samples received four (4) or more hours after collection are accetable, but results will be modified as follows: SYNST = Sample stability period exceeded 4 hours, Calcium pyrophosphate dehyrate crystals dissolve with time, therefore false negatives can occur.
Additional information Synovial fluid analysis does not include cytological evaluation. If this is required, a separate sample must be submitted to Anatomic Pathology. For questions, contact AP at 406-4365.

Crystal identification is included routinely when a cell count and differential is ordered on joint fluid. There is a > 95% change of detecting intraleukocytic urate crystals in an acutely gouty joint (and in approx 75% of asymptomatic patients); the few negative fluids are usually positive on repeat aspiration a few hours later. False positive results can occur due to the similar needle- or rod-like shape and birefringence seen occasionally with cholesterol crystals or with crystalline preparations of corticosteroids such as betamethasone and triamcinolone. Cartilage gragments and calcium oxalate crystals can also be birefringent, but are usually distinguishable from urates by careful attention to morphologic details. Generally, more rectangular birefringent pyrophosphate crystals are seen in other arthritis's

Lithium heparin (light green top) may cause false positive crystals formation.

Based on a small UCSF study, the effect of storage on joint crystals was examined. Calcium pyrophosphate dihydrate (CPPD) crystals dissolve after several hours. Refrigeration did not prevent CPPD crystals from dissolution. However, Monosodium urate (MSU) crystals did not decrease in numbers significantly over the first few days. but decrease over a period of weeks. Refrigeration appeared to slow the dissolution of MSU crystals.
CPT coding 89051; 89060 (crystal identification)
Last Updated 10/10/2014 11:28:51 AM
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