Page 140 - Canine Lameness

Assess amount of synovial fluid

Normal to
No fluid
increased

<0.1 ml 0.1–0.5 ml >0.5 ml
Use ultrasound
guidance or
attempt alternative
approach Make fresh smear Make fresh smear Make fresh smear Cytology
to joint
(see Chapter7)
EDTA tube* EDTA tube*
(purple top) (purple top) cytospin and TNCC, TP ,
No fluid analysis
possible
Flush hub fluid into Flush hub fluid into At least 0.5 ml in
blood culture flask** blood culture flask** blood culture flask Culture

No additive tube
(red top)*** and lactate glucose, Culture,
Figure 9.1 Algorithm for the prioritization of sample for synovial fluid. Due to the limited amount of joint fluid sample available, the clinician must prioritize
allocation of the available sample. [*Most automated hematology analyzers require a minimum of 200 μl to process the sample submitted. If there is limited
sample, the reader is encouraged to use the appropriate size EDTA tube, which generally requires submission in a pediatric/small tube. Submission in the
appropriate size tube is critical because inappropriate anticoagulant to sample ratios can cause erroneous results. **If limited sample is available and an
infectious etiology is suspected, some labs suggest submitting the capped needle directly to the diagnostic laboratory. Please contact the lab beforehand to
ensure this is possible and provide instructions to flush the needle hub using sterile technique prior to processing cultures. Alternatively, the content of the
syringe may be sterilely flushed into the culture media. ***If sufficient sample is available, red top tubes should be used to collect the additional sample. Further
tests such as a secondary culture (in addition to the culture from the blood culture flask), mucin clot test, and biochemical analytes (such as lactate, glucose, and
total protein) may be performed. Please contact the reference laboratory to ensure that use of these latter assays is available and validated for synovial fluid.]