L9: Synovial Fluid Analysis

Question 1

Synovial fluid modified by addition of:

Answer 1

• mucin and lubricin
• mononuclear cells
• cartilage components
• inflamm. Mediators

Question 2

3 layers of joint capsule

Answer 2

Fibrous
Vascular
Synovium (innermost)

Question 3

Fx of synovial fluid

Answer 3

• joint lube
• cartilage metabolism
• stability

Question 4

Goal of synovial fluid analysis**

Answer 4

Classify abnormal fluids as inflammatory neutrophilic or non-inflammatory mononuclear**

-based on physical features, protein conc, nucleated cell count, and microscopic exam (

Question 5

Normal joint volume

Question 6

Yellow jt. Fluid

Answer 6

Can be caused by cells (ie. WBC), crystals

Question 7

Yellow-orange jt. Fluid

Answer 7

RBC breakdown

Question 8

Red jt. Fluid

Answer 8

Hemorrhage

Question 9

Coudy fluid

Answer 9

• Cells (WBC, RBC, bacteria, tumor)
• Fibrin
• Crystals

Question 10

Normal joint fluid viscosity

Answer 10

• very high due to mucin and lubricin
• Can be decreased if broken down by proteases from bacteria or WBCs, diluted, or dec. production due to synovium damage
• microscopically, should see dense granular eosinophilic background to slide

Question 11

Mucin clot test

Answer 11

Put fluid in red top in acetic acid; should clot

*EDTA degrades mucin!

Question 12

Normal nucleated cell count

Answer 12

Dogs:

Question 13

Calculating nucleated cells/uL

Answer 13

= avg. # of nucleated cells/field x (objective power)2

Question 14

Functions of microscopic exam of synovial fluid*

Answer 14

• estimate mucin content (viscosity)
• est. nucleated cell count
• perform differential cell count
• examine slide for abnormalities

Question 15

Clasmatocyte

Answer 15

Synovial lining cell

Question 16

Normal synovial fluid micro exam

Answer 16

> 90% mononuclear cells (macs, lymphs, clasmatocytes)

Question 17

Ddx for non-inflammatory mononuclear jt. Fluid

Answer 17

1) DJD
- most common arthropathy
- usually dx w/o fluid analysis
- need rads to dx**

2) Trauma
3) Hemarthrosis
- from trauma, neoplasia, or bleeding diathesis

4) Neoplasia
- more common in middle age, large breeds, large joints
- Synovial cell sarcoma, histiocytic sarcoma, synovial myxoma, etc.

Question 18

Ddx for inflammatory neutrophilic jt. Fluid

Answer 18

1) Infectious
- bacterial (septic)
- tick-borne
- fungal
- protozoal
- viral
- mycoplasma
2) Immunologic (nonerosive or erosive)
3) Nonimmunologic

Question 19

Normal synovial fluid doesn’t clot and has no fibrinogen

Answer 19

:)

Question 20

Types of nonerosive immunologic inflammatory neutrophilic jt. Dz

Answer 20

• idiopathic (most common K9 inflam. Polyarthropathy**)
• reactive
• SLE (autoimmune, polysystemic, renal, etc.)
• lymphoplasmacytic
• eosinophilic
• breed-specific (spaniels, shar pei fever)

Question 21

Types of EROSIVE immunologic inflammatory neutrophilic jt. Dz

Answer 21

Idiopathic (rheumatoid)
Erosive polyarthritis of greyhounds (assoc. with pneumonia)
Felince chronic progressive polyarthritis (male cats**, FeSFV + FelV)