CLINMIC LEC SYNOVIAL FLUID

Synovial fluid

A naturally viscous ultrafiltrate of the plasma present within the synovial cavity of free-moving joints.

Provides lubrication and sole nutrient source for joint tissue.

Diarthroses

The synovial cavity of free-moving joints

Knee cavity

Largest volume of synovial fluid is found in the:

Bulge test

Test to check if there is enough amount of joint fluid

Arthrocentesis

Method of collection for synovial fluid; fluid is aspirated using a needle

Sterile heparinized or SPS tube

Tube for gram stain and culture

Heparin or liquid-EDTA tube

Tube for cell counts

Nonanticoagulated tube

Tube for other tests

Sodium fluoride tube

Tube for glucose analysis

Chemistry in red top or gray top tube - 1-3 mL

Give the section for tube #1 and its volume.

Microscopy in sodium heparin or liquid EDTA - 2-5 mL

Give the section for tube #2 and its volume.

Microbiology in sterile yellow tube or sodium heparin or sterile red top - 3-10 mL

Give the section for tube #3 and its volume.

Powdered anticoagulants

Contraindicated because they may produce artifacts interfering crystal analysis.

Powdered EDTA

Lithium heparin

Oxalate

3 powdered anticoagulants contraindicated (PLO)

Refrigeration promotes crystallization

Why are synovial joint specimen not refrigerated?

STAT

Manner of handling synovial spx

6 hours of fasting prior to collection

If glucose testing is to be performed on synovial fluid, how many hours does the patient need to fast?

Colorless to pale yellow and clear

Normal appearance of synovial fluid

Yellow and clear

Appearance of synovial fluid seen in non-inflammatory effusions

Yellow and cloudy

Appearance of synovial fluid seen in non-inflammatory joint disorders

White and milky

Appearance of synovial fluid with presence of crystals

Red and turbid

Appearance of synovial fluid with hemorrhage in joint

Hyaluronic acid

Substance responsible for viscosity in synovial fluid

4-6 cm in length

Normal viscosity of synovial fluid in string test

< 3 cm

Synovial fluid with poor viscosity will forma string of __________ or run out of the syringe and down the side of the test tube like water.

This is associated with presence of an inflammatory process.

String test

Tests ability to form a string from the tip of a syringe

Hyaluronidase

If synovial fluid is too viscous, what to add so that you can perform testing?

Mucin clot test

other name for Rope’s test

Rope’s test

uses 2-5% acetic acid to estimate the integrity of the hyaluronic acid-protein complex

Tight ropy clot

Normal synovial fluid in Rope’s test will form a _____________ upon addition of acetic acid.

Good

Solid clot

Fair

Soft clot

Poor/Low

Friable clot

Very poor/Poor

No clot at all

Glucose

Most frequent chemical examination done on synovial fluid

< 10 mg/dL lower than blood glucose

Normal synovial fluid glucose

Arthritis

Glucose in synovial fluid is associated with?

< 60 mg/dL

Septic arthritis glucose level in synovial fluid

< 3 g/dL

Normal synovial protein level

Fibrinogen

Beta 2 macroglobulin

Alpha 2 macroglobulin

All proteins of the serum are seen in synovial fluid except? (FBA)

Ankylosing spondylitis

HLA B27

Ankylosing spondylitis

Arthritis

Arthropathies in Crohn’s disease

Gout

Psoriasis

Reiter syndrome

Ulcerative colitis

7 conditions where in protein in synovial fluid is increased

6-8 mg/dL

Uric acid normal value in synovial fluid

Gouty arthritis

Abnormally high uric acid in synovial fluid signifies:

< 25 mg/dL

Normal lactic acid levels in synovial fluid

>1000 mg/dL

Lactic acid is helpful in diagnosing septic arthritis wherein levels could reach up to?

Total leukocyte count

Most commonly performed cell count on synovial fluid

< 200 cells per uL, < 25% neutrophils

Normal amount of WBCs in synovial fluid

Refrigerate

Total leukocyte count must be performed STAT, otherwise what to do with the specimen?

Neubauer counting chamber

Counting chamber used for synovial fluid leukocyte count

Normal saline solution

Commonly used diluent for synovial fluid

0.37% Hypotonic saline

1% Saline with saponin

0.1 N HCl

3 diluting fluids if there is a need to lyse RBCs

Methylene blue

Used to stain WBCs

Reiter cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Vacuolated macrophages with ingested neutrophils

Ragocyte or RA cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Neutrophils with dark cytoplasmic granules of precipitated rheumatoid factor

LE cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Neutrophil containing characteristic round body

Tart cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Monocytes with engulfed nuclear material

Synovial living cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Single or multinucleated cells that resembles macrophages and mesothelial cells

Cartilage cells

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Large, multinucleated cells

Rice bodies

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Macroscopically resemble polish rice; macroscopically show COLLAGEN and FIBRIN

Fat droplets

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Refractile intracellular and extracellular globules; stain with Sudan dyes

Hemosiderin

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Inclusions within cluster of synovial cells

Ochronotic shards

SIGNIFICANT CELLS IN THE SYNOVIAL FLUID

• Debris from metal and plastic joint prosthesis; ground pepper-like granules

Macrophage (60-65%)

Most predominant cell type in synovial fluid

Reactive arthritis

Reiter cells are associated with:

Decreased renal excretion producing elevated blood levels

Cartilage and bone degeneration

Medication

Synovial fluid crystals are formed due to:

Monosodium urate

Needle-like crystals that can be seen intracellularly or extracellularly

Naturally strongly birefringent

Calcium pyrophosphate dihydrate

Rhombic, rod-shape crystals that can be seen intracellularly and extracellularly

Can be found in vacuoles inside cell

Naturally WEAK birefringent

Compensated polarized microscopy

Best technique to identify crystals in synovial fluid

Parallel - yellow

Perpendicular - blue

Monosodium urate is negatively birefringent.

Negative birefringence means that when parallel it is color __________ and when perpendicular it is color _________

Parallel - blue

Perpendicular - yellow

Calcium pyrophosphate dihydrate (CPPD) is positively birefringent.

Positive birefringence means that when parallel it is color __________ and when perpendicular it is color _________

Gout

Monosodium urate crystals are found in what condition?

Pseudogout

Calcium pyrophosphate dihydrate are found in what condition?

Cholesterol crystals

Notched, rhombic plates

Extracellular

Corticosteroid

Flat, variable shapes

Injections

Positive AND negative birefringence

Calcium oxalate

Envelope shape

Renal dialysis

Calcium phosphate

Small particles

Osteoarthritis

Electron microscopy

Calcium phosphate crystals need what type of microscopy for identification?

MSU

Cholesterol

Calcium oxalate

3 crystals that are negatively birefringent (MCC)

Type 1 Joint disorder (Noninflammatory)

Clear yellow fluid with good viscosity

WBCs <1000 per uL; neutrophils < 30%

Normal glucose

Type 2 Joint disorder, immunologic (Inflammatory)

Cloudy yellow fluid with poor viscosity

WBCs 2000-75,000 per uL; neutrophils > 50%

Decreased glucose

Possible presence of autoantibodies

Type 2 Joint disorder, crystal-induced (Inflammatory)

Cloudy or milky fluid with low viscosity

WBCs 100,000 per uL; neutrophils < 70%

Decreased glucose level

Presence of crystals

Type 3 Joint disorder, Microbial infections (Septic)

Cloudy, yellow-green fluid with variable viscosity

WBCs 50,000-100,000 per uL; neutrophils > 75%

Decreased glucose level

Positive for culture and Gram stain

Highest amount of WBC in a joint disorder

Type 4 Joint disorder (Hemorrhagic)

Cloudy, red fluid with low viscosity

WBCs equal to blood per uL; neutrophils equal to blood

Normal glucose level

Staph

Strep

Haemophilus

Neisseria gonorrheae

4 bacteria that can cause septic arthritis

Type 1 and 4

2 joint disorders wherein glucose is normal