Synovial fluid Flashcards
Viscosity of synovial fluid is due to
Hyaluronic acid
Hyaluronic acid is produced by
Type B synoviocytes
Functions of synovial fluid
Lubricates joints, reduces friction, provides nutrients, lessens joint compression shock
Method of synovial fluid collection
Arthrocentesis
Normal synovial fluid volume
<3.5 mL
Inflammation synovial fluid volume
> 25 mL
Tube for chemical and immunologic evaluation
Plain red top tube
Anticoagulant for synovial fluid for hematology
Sodium heparin/Liquid EDTA
Powder anticoagulants issue
Interference with crystal ID
Effect of refrigeration on synovial fluid
Causes additional crystals
Tube for microbiological studies
Sterile anticoagulant tube (heparin or SPS)
Deeper yellow synovial fluid
Inflammation
Greenish synovial fluid
Bacterial infection
Red synovial fluid
Traumatic tap or hemorrhagic arthritis
Turbid synovial fluid
WBCs, synovial cell debris, or fibrin
Milky synovial fluid
Presence of crystals
Normal viscosity of synovial fluid
4-6 cm long
Normal hyaluronic acid level
0.03-0.4 g/dL
Ropes test reagent
2-5% acetic acid
Ropes test: Solid clot
Good
Ropes test: Soft clot
Fair
Ropes test: Friable clot
Low
Ropes test: No clot
Poor
Diluting fluids for synovial fluid
NSS with methylene blue, Hypotonic saline, Saline with saponin
Effect of acetic acid on WBC diluting fluid
Causes clot formation
Action for very viscous synovial fluid
Add hyaluronidase
Predominant WBC in normal synovial fluid
65% monocytes and macrophages
Normal neutrophil percentage in synovial fluid
<25%
Normal lymphocyte percentage in synovial fluid
<15%
Cell inclusion in synovial fluid for bacterial sepsis, crystal-induced inflammation
Neutrophil (PMN)
Cell inclusion in synovial fluid for nonseptic inflammation
Lymphocyte
Cell inclusion in synovial fluid for normal, viral inclusion
Macrophage (monocyte)
Cell inclusion in synovial fluid for lupus erythematosus
LE cell
Cell inclusion in synovial fluid for reactive arthritis
Reiter cell (neutrophage)
Cell inclusion in synovial fluid for tuberculosis, septic, and rheumatoid arthritis
Rice bodies
Cell inclusion in synovial fluid for rheumatoid arthritis and immunologic inflammation
RA cell (ragocyte)
Cell inclusion in synovial fluid for onchronotic arthropathy, alkaptonuria, onchronosis
Onchronotic shards (ground pepper appearance)
Cell inclusion in synovial fluid for osteoarthritis
Cartilage cells
Cell inclusion in synovial fluid for normal, disruption of arthrocentesis
Synovial lining
Cell inclusion in synovial fluid for traumatic injury, chronic inflammation
Fat droplets
Cell inclusion in synovial fluid for pigmented villonodular synovitis
Hemosiderin
Neutrophil with dark cytoplasmic granules containing precipitated rheumatoid factor
RA cell (ragocyte)
Crystal in synovial fluid with (+) birefringence seen in pseudogout
Calcium pyrophosphate
Crystal in synovial fluid seen in gout (needle-shaped)
Monosodium urate
Crystal in synovial fluid seen in extracellular with notched, rhombic plates
Cholesterol
Crystal in synovial fluid seen due to injections (flat, variable-shaped plates) (+/- birefringence)
Corticosteroid
Crystal in synovial fluid seen in renal dialysis (enveloped shape)
Calcium oxalate
Crystal in synovial fluid seen in osteoarthritis (small particles requiring EM) (no birefringence)
Apatite (calcium phosphate)
Detects presence or absence of birefringence
Polarizing microscope
Red compensator in polarizing microscope is placed where
Between crystal and analyzer
Control slide for MSU polarization is prepared using
Betamethasone acetate corticosteroid
MSU crystals run ___ to long axis and produce ___ birefringence and ___ color
Parallel; negative; yellow
Molecules of CPPD run ___ and produce ___ color and ___ birefringence
Perpendicular; blue; positive
Normal glucose level of synovial fluid
<10 mg/dL
Formula for glucose test in synovial fluid
Blood glucose - SF glucose
Normal value of lactate in synovial fluid
<25 mg/dL
Normal value of protein in synovial fluid
<3 g/dL
Normal value of uric acid in synovial fluid
Same as blood
Normal enzymes in synovial fluid
ACP, ALP, GGT, MURA, ADA, CD, LDH, AST (FOR RA)
Common organisms infecting synovial fluid
S. aureus, Streptococcus, Haemophilus, N. gonorrhea
Laboratory findings for non-inflammatory synovial fluid
Clear, yellow; good viscosity; WBC: <1000/uL
Laboratory findings for inflammatory synovial fluid (immunologic)
Cloudy, yellow fluid; poor viscosity; WBC: 2,000-75,000/uL; >50% neutrophils; decreased glucose; (+) autoantibodies
Laboratory findings for inflammatory synovial fluid (crystal-induced)
Cloudy or milky; low viscosity; WBC: 100,000/uL; (+) crystals; decreased glucose
Laboratory findings for septic synovial fluid
Cloudy, yellow-green fluid; variable viscosity; WBC: 50,000-100,000/uL; >75% neutrophils; (+) culture and Gram stain
Laboratory findings for hemorrhagic synovial fluid
Cloudy, red fluid; low viscosity; (+) RBCs