SYNOVIAL FLUID

synovial fluid

• is viscous ultra-filtrate of plasma that circulates in diarthroses (movable joints)

• produced by synoviocytes (type B cells) in the synovial membrane

• term “synovial” comes from the latin word ovum (egg), referring to its egg-white like appearance

arthrocentesis

• method of specimen collection of synovial fluid

• normal synovial fluid does not clot

less than 3.5 mL

• specimen volume

• normal in adult knee cavity

colorless to pale yellow

• normal color of synovial fluid

deeper yellow

• inflammation

greenish tinge

• bacterial infection

traumatic tap

• red

turbid

• white blood cells

milky

• presence of crystals

hyaluronic acid

• makes the synovial fluid viscous due to its polymerization

4.6 cm long

• normal string length

0.3-0.4

• normal hyaluronic acid concentration

ropes or mucin clot

• hyaluronic polymerization

• evaluates the degree of polymerization of mucoproteins (mainly hyaluronic acid) in semen

2.5% acetic acid

• reagent used in ropes or mucin clot

good, firm clot

• normal synovial fluid

soft clot or friable clot

• inflammatory disorder

no clot

• severe arthritis or infection (degraded hyaluronic acid)

less than 200 ul

• normal wbc count in synovial fluid

NSS, saline with saponin

• diluting fluid in white blood cell count

less than 2000 ul

• normal red blood cells count in synovial fluid

le cells

• neutrophil containing ingested round body causing lupus eythematosus

reiter cells

• vacuolated macrophage with ingested neutrophils causing reiter syndrome

ragocyte (ra cell)

• neutrophil with dark cytoplasmic granules containing immune complexes causing rheumatoid arthritis

rice bodies

• macroscopically resemble polished rice causing tuberculosis arthritis

ochronotic shards

• debris from metal and plastic joint prosthesis with “ground pepper appearance” causing ochronotic arthropathy

cartilage cell

• large, multi-nucleated cells causing osteoarthritis

monosodium urate

• gout

calcium pyrophosphate dihydrate (cppd)

• pseudogout

cholesterol crystals

• chronic arthritis

calcium oxalate

• renal dialysis patients

polarizing microscope

• detects for the presence or absence of birefringence

glucose

• most frequently tested; less than 10 mg/dL (normal)

• amount of glucose: blood glucose - synovial fluid glucose

• low sf glucose in inflammatory and septic arthritis due to increased glycolysis by neutrophils and bacteria

lactate

• less than 250 mg/dL (normal)

• increased lactate in septic arthritis (bacterial metabolism) an sometimes in rheumatoid arthritis

group I (non-inflammatory disorders)

• degenerative joint disorders

• osteoarthritis, traumatic arthritis

• clear, pale yellow fluid

• high viscosity (normal hyaluronic acid)

• wbc count: less than 2000 ul (mostly mononuclear cells)

• normal glucose and protein levels

group II a (immunologic inflammatory disorders)

• rheumatoid arthritis (ra), systemic lupus erythematosus (sle), scleroderma

• cloudy fluid, decreased viscosity

• wbc count: 2000-75000 ul (predominantly neutrophils)

• decreased glucose, increased protein

• presence of autoantibodies

group II b (crystal-induced disorders)

• gout (monosodium urate crystals), pseudogout (cppd)

• milky or cloudy fluid

• needle or rhomboid shaped crystals seen under polarized light

• wbc count: variable, often increased with neutrophils

• glucose: normal to decreased

group III (septic disorders)

• bacterial, fungal, or mycobacterial infections

• septic arthritis, gonococcal arthritis, tuberculosis arthritis

• purulent fluid (greenish, turbid)

• wbc count: more than 50000 ul (mostly neutrophils)

• very low glucose, increased lactate

• positive gram stain and culture

group IV (hemorrhagic disorders)

• trauma, coagulation disorders, anticoagulant therapy, neoplasm

• bloody synovial fluid

• rbc count significantly increased

• wbc count: variable

• glucose and protein: normal