Test Overview

Test Methodology

Direct polarized microscopy

Test Usage

Aid in differential diagnosis of gout or pseudogout.

Reference Range*

Crystal exam negative (no crystals seen).

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details

Days Test Performed

Daily, 24 hours

Analytic Time

24 hours

Soft Order Code


MiChart Code

Crystal Exam, Body Fluid



Crystal Exam, Synovial Fluid
Joint Fluid Crystal Exam
Synovial Fluid Crystal Exam

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STAT Availability

STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).

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Specimen Requirements

Offsite Collection Instructions

Collect specimen using aseptic technique. For optimal results, specimen should reach laboratory within 1 hr. of collection.If specimen must be stored, refrigeration is recommended. Specimen must be received within 24 hours of collection.

Special Handing

Send specimen to laboratory within 1 hour of collection.

Rejection Criteria

Specimens received in syringes, vacuum bottles, large containers,green lithium heparin Vacutainer® tubes or plastic red top Vacutainer® tubes containing clot activator will be rejected. Specimens exceeding the storage criteria or collected in a crystalline anticoagulant tube will be rejected.


Red Top Tube

Normal Volume

1 mL synovial fluid only

Minimum Volume

1 mL synovial fluid only

Additional Information

Test may include pathologist interpretation of results at an additional charge. By ordering this test, the clinician acknowledges that a pathologist interpretation will be performed and billed as a separate additional charge if indicated. Crystals most commonly identified in synovial fluid are negatively birefringent uric acid (gout) and positively birefringent calcium pyrophosphate (pseudogout). Occasionally cholesterol crystals are seen. Urate crystals are almost always seen intracellularly in acute gout. Calcium pyrophosphate crystals may be detected only after multiple aspirations of affected joints.

Billing Information

Fee Codes

CPT Code


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