L9: Synovial Fluid Analysis Flashcards
Synovial fluid modified by addition of:
- mucin and lubricin
- mononuclear cells
- cartilage components
- inflamm. Mediators
3 layers of joint capsule
Fibrous
Vascular
Synovium (innermost)
Fx of synovial fluid
- joint lube
- cartilage metabolism
- stability
Goal of synovial fluid analysis**
Classify abnormal fluids as inflammatory neutrophilic or non-inflammatory mononuclear**
-based on physical features, protein conc, nucleated cell count, and microscopic exam (
Normal joint volume
Yellow jt. Fluid
Can be caused by cells (ie. WBC), crystals
Yellow-orange jt. Fluid
RBC breakdown
Red jt. Fluid
Hemorrhage
Coudy fluid
- Cells (WBC, RBC, bacteria, tumor)
- Fibrin
- Crystals
Normal joint fluid viscosity
- very high due to mucin and lubricin
- Can be decreased if broken down by proteases from bacteria or WBCs, diluted, or dec. production due to synovium damage
- microscopically, should see dense granular eosinophilic background to slide
Mucin clot test
Put fluid in red top in acetic acid; should clot
*EDTA degrades mucin!
Normal nucleated cell count
Dogs:
Calculating nucleated cells/uL
= avg. # of nucleated cells/field x (objective power)2
Functions of microscopic exam of synovial fluid*
- estimate mucin content (viscosity)
- est. nucleated cell count
- perform differential cell count
- examine slide for abnormalities
Clasmatocyte
Synovial lining cell
Normal synovial fluid micro exam
> 90% mononuclear cells (macs, lymphs, clasmatocytes)
Ddx for non-inflammatory mononuclear jt. Fluid
1) DJD
- most common arthropathy
- usually dx w/o fluid analysis
- need rads to dx**
2) Trauma
3) Hemarthrosis
- from trauma, neoplasia, or bleeding diathesis
4) Neoplasia
- more common in middle age, large breeds, large joints
- Synovial cell sarcoma, histiocytic sarcoma, synovial myxoma, etc.
Ddx for inflammatory neutrophilic jt. Fluid
1) Infectious
- bacterial (septic)
- tick-borne
- fungal
- protozoal
- viral
- mycoplasma
2) Immunologic (nonerosive or erosive)
3) Nonimmunologic
Normal synovial fluid doesn’t clot and has no fibrinogen
:)
Types of nonerosive immunologic inflammatory neutrophilic jt. Dz
- idiopathic (most common K9 inflam. Polyarthropathy**)
- reactive
- SLE (autoimmune, polysystemic, renal, etc.)
- lymphoplasmacytic
- eosinophilic
- breed-specific (spaniels, shar pei fever)
Types of EROSIVE immunologic inflammatory neutrophilic jt. Dz
Idiopathic (rheumatoid)
Erosive polyarthritis of greyhounds (assoc. with pneumonia)
Felince chronic progressive polyarthritis (male cats**, FeSFV + FelV)
