Synovial Fluid (Textbook)

Question 1

Diarthroses

Answer 1

Cavities of the movable joints

Question 2

Synoviocytes

Answer 2

Specialized cells within the Synovial Membrane that secrete a mucopolysaccharide containing hyaluronic acid

Question 3

Synovial Fluid Formation

Answer 3

Synovial fluid is formed as an ultrafiltrate of plasma across the synovial membrane. The filtration is nonselective except for the exclusion of high-molecular-weight proteins.

Question 4

Arthrocentesis

Answer 4

Synovial fluid collected by needle aspiration

Question 5

Synovial Fluid Clots

Answer 5

Normal synovial fluid does not clot; however, fluid from a diseased joint may contain fibrinogen and will clot.

Question 6

Synovial Aspiration Anticoagulants

Answer 6

Therefore, fluid is often collected in a syringe that has been moistened with heparin.

Powdered anticoagulants should not be used because they may produce artifacts that interfere with crystal analysis.

Question 7

Normal Synovial Fliud Color

Answer 7

Normal viscous synovial fluid resembles egg white. The color becomes a deeper yellow in the presence
of noninflammatory and inflammatory effusions and may have a greenish tinge with bacterial infection.

Question 8

Synovial Fluid Viscosity Measrurement

Answer 8

Observe the fluid’s ability to form a string from the tip of a syringe, a test that easily can be done at the
bedside. A string measuring 4 to 6 cm is considered normal.

Question 9

Mucin Clot (Ropes) Test

Answer 9

Hyaluronate polymerization measurement: When added to a solution of 2% - 5% acetic acid, normal synovial fluid forms a solid clot surrounded by clear fluid.

Question 10

Cell Counts on Synovial Fluid

Answer 10

Manual counts on thoroughly mixed specimens are done using the Neubauer counting chamber.

Dilutions are necessary when fluids are turbid or bloody, normal saline can be used as a diluent.

Question 11

Synovial Fluid Normal Cell Count

Answer 11

Neutrophils should account for less than 25% of the differential count and lymphocytes less than 15%.

Question 12

Reiter Cells

Answer 12

Neutrophages, vacuolated macrophages with ingested neutrophils

Question 13

RA Cells

Answer 13

Ragocytes, neutrophils with small, dark cytoplasmic granules consisting precipitated rheumatoid factor

Question 14

Pigmented Villonodular Synovitis

Answer 14

Hemosiderin granules

Question 15

MSU Crystals

Answer 15

Found in cases of gout

Increased serum uric acid resulting from impaired metabolism of purines; increased consumption of high-purine-content foods, alcohol, and fructose; chemotherapy treatment of leukemias; and d_ecreased renal excretion of uric acid_ are the most frequent causes of gout.

Needle-shaped crystals, frequently seen sticking through the cytoplasm of the cell, lyse phagosome membranes - do not appear in vacuoles.
Birefringence produces a yellow color. This is considered negative.

Question 16

CPPD Crystals

Answer 16

Calcium pyrophosphate dihydrate (CPPD), seen with pseudogout.

Pseudogout is most often associated with degenerative arthritis, producing cartilage calcification and endocrine disorders that produce elevated serum
calcium levels.

Rhomboid-shaped, square, or short rods. Located within vacuoles of the neutrophils

Birefringence is blue color and positive birefringence.

Question 17

Other Crystals Found in Synovial Fluid

Answer 17

Hydroxyapatite (basic calcium phosphate) associated with calcified cartilage degeneration (Osteoarthritis and RA)

Cholesterol crystals associated with chronic inflammation

Corticosteroids after injections

Calcium oxalate crystals in renal dialysis patients.

Question 18

Crystal Findings

Answer 18

Both MSU and CPPD crystals are reported as being located extracellularly and intracellularly (within neutrophils); therefore, fluid must be examined before WBC disintegration.

Question 19

Glucose Test on Synovial Fluid

Answer 19

Markedly decreased glucose values indicate inflammatory (group II) or septic (group III) disorders.

Question 20

Synovial Fluid Protein Levels

Answer 20

Normal synovial fluid contains less than 3 g/dL protein (approximately 1/3 of the serum value). Increased levels are found in inflammatory and hemorrhagic disorders

Question 21

Synovial Fluid Uric Acid

Answer 21

Demonstration of an elevated synovial fluid uric acid level may be used to confirm the diagnosis when
the presence of crystals cannot be demonstrated in the fluid.

Question 22

Fluid Lactate or Acid Phosphatase

Answer 22

May be requested to monitor the severity and prognosis of rheumatoid arthritis (RA).

Question 23

Microbiological Tests for Synovial Fluid

Answer 23

• Staphylococcus
• Streptococcus
• Haemophilus
• Neisseria gonorrhoeae

Question 24

Antibodies in Synovial Fluid

Answer 24

The autoimmune diseases rheumatoid arthritis and systemic lupus erythematosus cause very serious joint inflammation and are diagnosed in the serology laboratory by demonstrating the presence of their particular autoantibodies in the patient’s serum.

Lyme disease can cause arthritis, demonstrating antibodies to the causative agent Borrelia burgdorferi in the patient’s serum can confirm the cause of
the arthritis.

Question 25

Charcot-Leyden

Answer 25

Caused by hyper-eosinophilic syndromes

Bipyramidal hexagons