AUBF MTAP (Synovial Fluid)

• Lubrication for the joints

• Cushioning joints during jogging

• Provides nutrients for cartilage

• Reduces friction between bones during movement

The functions of synovial fluid include all of the following:

Articular cartilage

Smooth cartilage that covers the ends of bones within the joint, facilitating smooth movement

Joint capsule

• A fibrous structure that encloses the joint

• Lined with the synovial membrane that produces synovial fluid

• Provides protection and stability

Synovial membrane

Responsible for the production of synovial fluid; contains specialized cells called synoviocytes

Type A Synoviocytes

• Macrophage-like cells involved phagocytosis

• Scavenger of joint structure and clear debris in joint fluid

• Found in superficial layer

Type B Synoviocytes

• Fibroblast-like cells that produce hyaluronic acid, fibronectin, and collagen

• Contributing to synovial fluid viscosity

• Clearing of debris and protecting joint in inflammation

Approximately 25% of plasma concentration

A small amount of protein contains:

Hyaluronate

• Contributes to the viscosity of synovial fluid

• Crucial for lubricating joint movement

Arthritis

Synovial fluid analysis is important for diagnosing the pathological origin of:

Colorless to pale yellow

What is the normal synovial fluid color?

<200 cells/μL

Normal leukocyte count of synovial fluid

Needle aspiration guided by ultrasound

Arthrocentesis is a procedure used to collect synovial fluid from joints by:

<3.5 mL

Normal amount of synovial fluid in adult knee cavity

>25 mL

Amount of synovial fluid in adult knee cavity during inflammation

TRUE

TRUE OR FALSE

Normal synovial fluid does not clot

Fibrinogen

Synovial fluid from diseased joint may clot due to the presence of:

Heparin

Which anticoagulant is used in collection syringe?

Red top

What tube is used for Tube 1 after fluid collection?

Green or EDTA

What tube is used for Tube 2 after fluid collection?

Green or yellow top

What tube is used for Tube 3 after fluid collection?

Sodium heparin or SPS

Which anticoagulant(s) is used to preserve microorganisms?

Non inflammatory and inflammatory disease

Synovial fluid with deeper yellow color indicates:

Bacterial infection

Synovial fluid with greening tinge indicates:

Presence of crystals

Synovial fluid that appears milky indicates:

Impaired hyaluronate production or polymerization

Decreased viscosity is caused by:

Mucin clot test (Ropes Test)

Which test is useful for distinguishing synovial fluid from other fluid?

Acetic acid

What reagent is used in Ropes Test?

WBC count

Most routinely used for cell counting

Specimen should be refrigerated

To prevent cellular disintegration, counts should be performed as soon as possible or:

TRUE

TRUE OR FALSE

Acetic acid can cause clot formation and cell clumping

• Cytocentrifuged preparations

• Thinly smeared slides

Differential counts should be performed on:

• Monocytes

• Macrophages

• Synovial tissue cells

What are the predominant cells in synovial fluid?

Septic arthritis

Increase in neutrophils suggest:

Non-septic inflammatory conditions

Increase in lymphocytes indicate:

• LE cell

• Reiter cell

• RA cell

• Lipid droplets

Which cells are seen in crush injuries?

Hemosiderin granules

These are seen in pigmented villonodular synovitis

Reiter cell

Which cell is seen in reactive arthritis?

Lymphocyte

Which cell is seen in nonseptic inflammation?

Cartilage cell

Which cell is seen in Osteoarthritis?

Rice body

Which cell is seen in tuberculosis, septic and rheumatoid arthritis?

Fat droplet

Which cell is seen in traumatic injury and chronic inflammation?

Monosodium urate (MSU)

It is routinely seen as needle-shaped and observed in gout

Calcium pyrophosphate dihydrate (CPPD)

It usually appears rhomboid-shaped or square but may appear as short rods

• Found in pseudogout (chondrocalcinosis)

Hydroxyapatite

Which crystal is found in calcified cartilage degeneration?

Cholesterol

Which crystal is seen in chronic inflammation? (RA)

Calcium oxalate

Which crystal is found in patients undergoing renal dialysis?

Hydroxyapatite

Which crystal requires electron microscopy for visualization?

Corticosteroid

Which crystal looks irregular with jagged or separated edges; broken pieces

Hematin

Yellow-brown (golden) rhomboid crystal under brightfield microscopy

TRUE

TRUE OR FALSE

MSU is more highly birefringent than CPPD

Yellow

Under polarized light, MSU appears to be what color?

Blue

Under polarized light, CPPD appears to be what color?

Hydroxyapatite

Which crystal does not show birefringence?

Glucose determination

Which chemistry test is frequently requested for synovial fluid?

Sodium chloride

What is the anticoagulant used in glucose testing?

10 mg/dL

Normal synovial fluid glucose should be within:

8-hour fast

Blood and synovial fluid samples should be collected simultaneously, preferably after an:

Glucose is typically 10–20 mg/dL lower than blood

GLUCOSE LEVEL INTERPRETATION

Noninflammatory and hemorrhagic joint disorders

Glucose is 0-40 mg/dL below blood glucose

GLUCOSE LEVEL INTERPRETATION

Inflammatory disorders

Glucose can be 20-100 mg/dL lower than blood glucose

GLUCOSE LEVEL INTERPRETATION

Septic arthritis

< 3.0 g/dL

Normal synovial fluid protein level

Inflammatory and hemorrhagic disorders

Increased protein is found in patients with:

Uric acid

It is used to confirm gout when monosodium urate (MSU) crystals cannot be demonstrated in the fluid

Elevated serum uric acid

It is a well-known indicator of gout

MSU crystals are not detected

Synovial fluid uric acid is measured when:

Elevated septic arthritis

Increased lactate levels are seen in:

• >9 mmol/L

• 81 mg/dL

Lactate levels that indicate bacterial arthritis and warrant immediate treatment

• ACP / ALP

• GGT

• LDH

Which enzymes can be monitored in rheumatoid arthritis (RA) to assess disease severity and prognosis?

• Staphylococcus

• Streptococcus

• Haemophilus

• Neisseria gonorrhoeae

The most frequent causes of synovial fluid infection:

• Borrelia burgdorferi

• Mycobacterium tuberculosis

• Chlamydia trachomatis

• N. gonorrhoeae

PCR is used for detecting hard-to-culture organisms such as:

Serological tests

Used to evaluate the involvement of the immune system in joint inflammation, particularly in autoimmune diseases like rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE)

RA and SLE

These conditions cause severe joint inflammation and are diagnosed by detecting specific autoantibodies in serum

Lyme disease

Arthritis is a frequent complication of: