Synovial Fluid

What is synovial fluid?

ultrafiltrate of plasma between the joints

What are the 3 main functions of synovial fluid?

lubrication, nutrients, and shock absorption

Freely movable joints due to synovial fluid are called:

• Synarthroses

• Amphiarthroses

• Diarthroses

• Fibrous joints

Diarthroses

Which component of synovial fluid is primarily responsible for its viscosity and lubrication?

• Lubricin

• Water

• Hyaluronic acid

• Plasma proteins

Hyaluronic acid

What is arthritis?

pain and stiffness in the joints due to membrane damage

What are the 4 classifications of synovial fluid disorders?

1. noninflammatory arthritis

2. inflammatory arthritis

3. septic arthritis

4. hemorrhagic arthritis

Degenerative joint disorders can cause what type of synovial fluid disorder?

noninflammatory arthritis

What is an examples of a noninflammatory joint disorder that causes noninflammatory arthritis?

osteoarthritis (degenerative joint disorder)

A synovial fluid specimen has the following test results:

appearance: yellow, clear

glucose: 85 mg/dL (blood is 90 mg/dL)

WBC count: 1500/uL

differential: neutrophils 15%

culture: negative

What type of synovial disorder is this?

• noninflammatory

• inflammatory (immunological)

• inflammatory (crystal-induced)

• septic

• hemorrhagic

noninflammatory

Immunologic joint disorders and crystal formation can cause what type of synovial fluid disorder?

inflammatory arthritis

What are 3 examples of immunologic joint disorders that can cause inflammatory arthritis?

1. Lupus erythematosus (LE)

2. rheumatoid arthritis (RA)

3. Lyme disease

A synovial fluid specimen has the following test results:

appearance: yellow, cloudy

glucose: 60 mg/dL (blood is 90 mg/dL)

WBC count: 4,000/uL

differential: neutrophils 60%

culture: negative

What type of synovial disorder is this?

• noninflammatory

• inflammatory (immunological)

• inflammatory (crystal-induced)

• septic

• hemorrhagic

inflammatory (immunological)

What are some examples of crystal-induced inflammatory arthritis?

gout and pseudogout

A synovial fluid specimen has the following test results:

appearance: yellow, milky

glucose: 60 mg/dL (blood is 90 mg/dL)

WBC count: 45000/uL

differential: neutrophils 75%

culture: negative

What type of synovial disorder is this?

• noninflammatory

• inflammatory (immunological)

• inflammatory (crystal-induced)

• septic

• hemorrhagic

inflammatory (crystal-induced)

Microbial infections can cause what type of synovial fluid disorder?

septic arthritis

A synovial fluid specimen has the following test results:

appearance: yellow-green, cloudy

glucose: 60 mg/dL (blood is 90 mg/dL)

WBC count: 80000/uL

differential: neutrophils 95%

culture: positive

What type of synovial disorder is this?

• noninflammatory

• inflammatory (immunological)

• inflammatory (crystal-induced)

• septic

• hemorrhagic

septic

The presence of blood in the joint is a characteristic of what synovial fluid disorder?

hemorrhagic arthritis

What 3 things can cause blood in the synovial fluid, leading to hemorrhagic arthritis?

1. trauma

2. tumors

3. coagulation deficiencies

A synovial fluid specimen has the following test results:

appearance: red/pink, cloudy

glucose: 85 mg/dL (blood is 90 mg/dL)

WBC count: 4500/uL

differential: neutrophils 40%

culture: negative

What type of synovial disorder is this?

• noninflammatory

• inflammatory (immunological)

• inflammatory (crystal-induced)

• septic

• hemorrhagic

hemorrhagic

What is the normal volume of synovial fluid?

< 3.5 mL

What is the normal color and clarity of synovial fluid?

colorless - pale yellow

clear

Patients with noninflammatory or inflammatory arthritis would have what color synovial fluid?

deeper yellow

Synovial fluid from a patient with septic arthritis or some kind of infection in the fluid would be what color?

green

Patients with hemorrhagic arthritis or had a traumatic tap would have what color synovial fluid?

red

Crystals in synovial fluid would have what affect on the clarity?

it would be milky

What are 4 cause that would make synovial fluid turbid?

1. WBCs

2. cellular debris

3. fibrin

4. crystals

Synovial fluid with normal viscosity will be able form strings how long?

4-6 cm

The mucin clot test adds what fluid to a patient’s synovial fluid to test for the viscosity?

acetic acid

When combined with acetic acid to test for viscosity, should normal synovial fluid form a clot or not clot?

form a clot

How many leukocytes should be seen in 1 uL of normal synovial fluid?

< 200 leukocytes/uL

A patient with septic arthritis would have how many leukocytes per 1 uL of synovial fluid?

> 100,000 leukoctres/uL

When performing cell counts (WBC/diff.) on synovial fluid, what fluid is added to dilute the specimen?

normal saline or methylene blue

What would you add to decrease the viscosity of synovial fluid to prepare it for cell counts?

hyaluronidase

After treatment with hyaluronidase, what should you do to prepare the sample for a cell counts?

incubate at 37C for 5 minutes

After incubation with hyaluronidase, what should you do to prepare the sample for a differential count?

cytocentrifuge

What are the cells normally found in synovial fluid?

monocytes, macrophages, and synovial tissue cells

What percentage of leukocytes should be neutrophils when performing a differential on synovial fluid?

< 25%

Increased neutrophils in synovial fluid is indication of what condition?

sepsis

What percentage of leukocytes should be lymphocytes when performing a differential on synovial fluid?

< 15%

Increased lymphocytes in synovial fluid is indication of what condition?

inflammation

What are neutrophils that have phagocytized nuclear material?

• lupus erythematosus (LE) cells

• Reiter cells/neutrophages

• ragocytes

• hemosiderin granules

lupus erythematosus cells

What are vacuolated macrophages with ingested neutrophils?

• lupus erythematosus (LE) cells

• Reiter cells/neutrophages

• ragocytes

• hemosiderin granules

Reiter cells/neutrophages

What cells are neutrophils with small, dark granules containing precipitated rheumatoid factor?

• lupus erythematosus (LE) cells

• Reiter cells/neutrophages

• ragocytes

• hemosiderin granules

ragocytes

What are pigmented villonodular synovitis?

• lupus erythematosus (LE) cells

• Reiter cells/neutrophages

• ragocytes

• hemosiderin granules

hemosiderin granules

Seeing lipid droplets in synovial fluid indicates what kind of injury?

crush injury

How many crystal formations should you see in synovial fluid?

none

What are 4 causes for crystals to form in synovial fluid?

1. metabolic disorders

2. decreased renal function

3. degeneration of bone/cartilage

4. corticosteroids

What are the 2 primary crystals found in synovial fluid?

1. monosodium urate (MSU)

2. calcium pyrophosphate dihydrate (CPPD)

MSU is the primary crystal found in (gout/pseudogout).

gout

What are 2 causes that could cause an increase in MSU formation in synovial fluid?

1. increased purines and uric acid

2. leukemia chemotherapy

What primary crystal is this?

MSU

CPPD is the primary crystal found in (gout/pseudogout).

pseudogout

What are 2 causes that could cause an increase in CPPD formation in synovial fluid?

1. degenerative arthritis

2. increased calcium levels

What primary crystal is this?

CPPD

Cholesterol is present in synovial fluid during what?

chronic inflammation

Corticosteroids are seen in synovial fluid after what?

injections

Calcium oxalate is seen in synovial fluid when patients have what condition?

renal failure

How long can a synovial fluid sit before examining for crystals?

should be performed ASAP

After initial viewing of synovial fluid, how find and differentiate crystals?

1. find crystals using polarized light

2. differentiate crystals using compensated polarized light

Light is allowed to pass through the polarized microscope when both fields are what?

aligned

All light is prevented from passing through the polarized microscope when both fields are what?

analyzer is perpendicular to polarizer

What is the purpose of the red/gamma compensator on a polarized microscope?

determines the type of birefringence (positive or negative)

What are the 2 identify factors of negative birefringence?

1. red/gamma compensator is parallel to crystal = crystal is yellow

2. red/gamma compensator is perpendicular to crystal = crystal is blue

Does this image represent positive or negative birefringence?

negative

Does MSU have positive or negative birefringence?

negative

What are the 2 identify factors of positive birefringence?

1. red/gamma compensator is parallel to crystal = crystal is blue

2. red/gamma compensator is perpendicular to crystal = crystal is yellow

Does this image represent positive or negative birefringence?

positive

Does CPPD have positive or negative birefringence?

positive

How does the glucose value of synovial fluid relate the the glucose value of blood?

< 10 mg/dL lower compared to glucose value of blood

What is the normal total protein of synovial fluid?

< 3 g/dL

Which procedure is used to collect synovial fluid?

• Arthroscopy

• Arthrography

• Arthrocentesis

• Arthrectomy

Arthrocentesis

How many mL of synovial fluid is collected for noninflamed and inflamed joint testing?

noninflamed: 3.5 mL

inflamed: > 25 mL

Clotting of synovial fluid indicates what?

fluid is diseased

When collecting synovial fluid for microbiology testing, what are the 2 tubes you can collect the fluid in?

heparin or sodium polyanethol sulfonate (SPS)

What are the 4 main organisms tested for in synovial fluid?

1. Staph

2. Strep

3. H. influenza

4. N. gonorrhoeae

When collecting synovial fluid for hematology testing, what tube do you use to collect the fluid in?

liquid EDTA

When collecting synovial fluid for glucose testing, what 2 tubes do you use to collect the fluid in?

1. nonanticoagulated

2. sodium fluoride

When collecting synovial fluid for other types of testing, what 2 tubes can you use to collect the fluid in?

1. heparin

2. nonanticoagulated