Chapter 14 Synovial Fluid Flashcards
Fluid within joint cavities. Examined to distinguish between septic, aseptic, or degenerative changes in joints commonly seen in arthritis, gout and autoimmune diseases
Synovial fluid
Label the missing terms
Functions of synovial fluid (3)
- Provides lubrication in joints
- provides nutrients to articulate cartilage
- reduces shock of joint compression during strenuous activities
Formation of synovial fluid (3)
- Ultrafiltrate of plasma across synovial membrane
- synoviocytes line membrane and secrete hyaluronate, the major contributor to viscosity and synthesizes collagenases for phagocytic activity
- normal amount in knee cavity <3.5 mL and does not clot
Needle aspiration for collection
Arthrocentesis
Fluid amount if inflamed
> 25 mL
Normal fluid vs. Diseased fluid
Normal does not clot, diseased clots
Normal knee fluid amount
3.5 mL
Collect in what tube for microbiology
Sterile heparinized
Collect in what tube for hematology
Liquid EDTA
Collect in what tube for glucose
Sodium fluoride
Test ASAP to avoid
Cellular lysis and changes in crystals
3 tubes used for collect: tube 1
No anticoagulant tube for chemical and immunologic studies
3 tubes used for collect: tube 2
Anticoagulant tube for microscopic studies
3 tubes used for collect: tube 3
Sterile anticoagulant tube for microbiological studies
What are the tests performed (6)
- Appearance and viscosity
- WBC and differential count
- crystal analysis: compensated polarizing microscopy
- microbiology: gram stain and culture
- chemistry: glucose, protein, uric acid
- serology: antigen-antibody, inflammation markers
Group?
- degenerative joint disorders
- osteoarthritis
- traumatic arthritis
Noninflammatory
Group?
-Immunologie disorders, rheumatoid arthritis, lupus, Lyme arthritis, crystal induced gout and pseudogout
Inflammatory
Group?
- microbial infection
Septic/infections
Group?
- traumatic injury, tumors, hemophilia, other coagulation disorders, anticoagulant overdose
- Joint prosthesis
Hemorrhagic
Finding for normal fluid
Colorless to pale yellow <3.5 mL
Finding for WBCs and cell debris. Rice bodies (collagen particles)
Turbidity
Finding for inflammation
Yellow
Finding for crystals
Milky
Finding for hemorrhage arthritis vs traumatic aspiration
Bloody
Finding for bacterial infection
Greenish
Finding for normal 4-6 cm string formation. Absent suggest bacterial infection
Viscosity (presence of hyaluronic acid)
Finding for normal: solid clot formation with acetic acid (ropes test)
Mucin clot for hyaluronate polymerization
Arthritis decreases
Polymerization
Normal amount of RBCs
<2000 per microliter
Traumatic tap or hemorrhage effusions cause
Increased RBCs
Normal amount of WBCs
<200 per microliter
Bacterial arthritis can cause
Increased WBCs
Used to concentrate cells and preserve morphology
Cytocentrifugation
More than 80% neutrophils associated with
Bacterial arthritis and urate gout
Normal amount of monocytes/macrophages, lymphocytes, and neutrophils
60% monocytes/macrophages, 30% lymphocytes, 10% neutrophils
Most common types of crystals present (5)
- Monosodium urate (gout)
- calcium pyrophosphate (pseudogout seen in degenerative arthiritis)
- cholesterol (chronic arthritic inflammation)
- steroid injections
- calcium based
Monosodium urate (MSU) crystals
Calcium pyrophosphate dihydrate (CPPD) crystals
Wet prep or Wright stained examination for crystals
Light microscopy
Examination for crystals:
Ability to refract light rays: fixed light above, rotating filter (polarizer) below. Both filters allow light to pass in only 1 direction
No light can pass = dark field
Birefringent material is seen as bright particle or crystal
Polarizing microscopy for birefringence
Examination for crystals:
ID crystal based on the velocity of light rays passing through the crystal’s grain (axis): positive or negative
Quartz red line compensator
Characteristics of monosodium urate crystals (4)
- Intra-or extracellular
- long, thin, and needle-like, pointed ends
- single or in bundles
- strongly birefringent, brilliant with polarized light
MSU Quartz red line compensator: parallel to the axis compensater=
Yellow color
MSU Quartz red like compensator: perpendicular to axis compensator=
Blue color
Runs parallel to the long axis, aligned with slow vibration; fast light is impeded, producing a yellow color (negative bifringence)
MSU molecules
Run perpendicular to long axis and impede the slow light producing a blue color (positive bifringence)
CPPD
MSU crystal with a plain light microscope
MSU crystal with polarized light
MSU crystal with quartz compensator
Characteristics of calcium pyrophosphate (CPP) (3)
- Intra- or extracellular
- short, rectangular
- weakly birefringent - may be difficult to see
CPP quartz red line compensator: parallel to the axis compensator=
Blue color
CPP Quartz red line compensator: perpendicular to axis compensatory =
Yellow color
CPP crystal with a plain light
CPP crystal with polarized light
CPP crystal with quartz compensator
- notched-plate shape
- birefringent
- seen in chronically inflamed joints- RA
Cholesterol crystals
- Distinguish from pathogenic crystals
- Maltese cross
Starch particles
Cholesterol crystals in joint fluid
- observe intracellularly on electron microscope
- tiny, needle-like crystals
Hydroxyapatite crystals
- Seen for months after steroid infections
- no clinical significance
- Look like MSU or CPP but yield conflicting results based on their birefringence
Corticosteroids
Normal glucose amount
Not less than 10 mg/dL of plasma glucose
Most frequent chemistry test
Glucose
A result of variety of joint diseases; only indicates inflammatory process
Increased total protein
Same levels as plasma; increased levels in fluid may cause monosodium rate (MSU) crystals
Uric acid
Increased from anaerobic glycolysis in the synovium; clinical value not yet established
Lactate
What test?
- infections caused by inflammation, trauma, and systemic infections
- gram stain and cultures are routinely performed
Microbiology tests
Infections agents seen on gram stain and culture
Bacteria, fungi, viruses, mycobacteria
All synovial fluid samples should be
Cultured
