Analysis of synovial fluid for crystals needs to consider the possibility of factors causing false positive and false negative results.
False positive for crystals:
(1) fibrin strands
(2) fragments of cartilage
(3) fragment of synovial villus
(4) dust
(5) talc
(6) fungal spores
(7) paper fibers
(8) precipitate secondary to handling or storage conditions, especially if left to dry out or refrigerated
(9) poor technique
(10) sampling of stable tissue deposit adjacent to joint
Drugs injected into the joint may form crystals. These may can cause a tissue reaction if present in large enough numbers.
False negative for crystals:
(1) poor technique
(2) very small crystals
(3) crystals present in small numbers
(4) dissolution of crystals secondary to handling or storage conditions
(5) obscuring blood
(6) failure to stain with Alizarin red (detects hydroxyapatite aggregates)
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Specialty: Surgery, orthopedic
