Muhammad Asif ZebLecture Hematology

IPMS-KMU

Objective Physiology and Composition of Synovial

Fluid

Specimen Collection

Laboratory TestingMacroscopic EvaluationChemical ExaminationMicroscopic Examination

Synovial FluidSynovial

syn(like) + ovia (egg)

“Joint Fluid”

Synovial FluidViscous fluid found in

the cavities of movable joints

Synovial membrane Inner membrane of

synovial joints Secretes synovial

fluid into the joint cavity

Contain specialized cells (synoviocytes)

CompositionHyaluronic acid

synthesized by the synovial membraneincrease the viscosity and elasticity of articular

cartilageslubricate the surface between synovium and

cartilage.

Lubricin secreted by synovial cells.

It is chiefly responsible for so called boundary layer lubrication, which reduces friction between opposing surfaces of cartilage.

Major FunctionsReducing friction LubricationLessen shockSupplying oxygen

and nutrients

Synovial Fluid: Specimen Collection

Bulge testThe Bulge test is used to determine if there is an abnormal amount of fluid surrounding a joint

Bulge test of joint for the detection of synovial effusion

Bulge Test

Specimen Collection

Arthrocentesis

Placement of needle in arthrocentesis of (A) elbow and(B) knee joints.

CollectionThree samples are collected.

NoteIf the specimen cannot be examined immediately, fluid should be frozen

and stored at -70°C until examined

Macroscopic Laboratory TestingVolumeColor and ClarityInclusionsViscosityClottingMucin Clot

Laboratory Testing: Macroscopic Volume

Normal up to <3.5 ml of fluid

Can reach up to 25 mlInflammation

Macroscopic Analysis: Color and ClarityColorless to pale yellow and clear

normalRed, brown, or xanthochromic

hemorrhage into the joint Yellow/clear

noninflammatory effusionsYellow/cloudy

inflammationWhite/cloudy/milky

Crystals

Macroscopic Analysis: Inclusions

Rice bodies. Free-floating aggregates of tissue appear

as rice bodies.rheumatoid arthritis (RA) Degenarated synovium enriched with

fibrin

Ochronotic shardsdebris from joint prosthesislook like ground pepper

A =ochronotic shards B =rice bodies

Macroscopic Analysis: Viscosity“Ropes” or “Mucin

Clot Test”Normal = 4-6 cm

When 2-5% acetic acid is added, normal synovial fluid will form a clot surrounded by clear fluid

Macroscopic Analysis: Clotting

Normal synovial fluid: Do not clotClotting of synovial fluid = fibrinogen

1.Damaged synovial membrane 2.Traumatic tap

Macroscopic Analysis: Mucin Clot“Ropes test” Estimation of hyaluronic

acid–protein complex integrity

The adding of acetic acid to normal synovial fluid, which causes clot formation.

Criteria:Compactness of the clotClarity of the supernatant fluid

Mucin TestGood : solid clotFair: soft clotLow: Friable clotPoor: No clot

Microscopic Analysis: Cell CountsTotal leukocyte count

<200 cells/uL

Why is the traditional WBC fluid not used for cell counting?

Because it contains ______________ which is responsible for clotting.

Can clear undiluted fluid be used for counting?

Microscopic Analysis: Cell CountsNeubauer Counting Chamber

Microscopic Analysis: Diff CountIncubate with hyaluronidase Neutrophils : <25% of the differentialLymphocytes: <15%Crystal: None present

Increase neutrophil: septic conditionIncrease cell count with increase lymphocyte:

nonseptic inflammation

Chemical Analysis: ProteinAll proteins found in plasma

Exception: various high–molecular weight proteins which may be present in very small amount

Fibrinogen

beta 2 macroglobulin

alpha 2 macroglobulin

Use common serum protein procedures

Chemical Analysis: Protein (cont.)Normal range <3 g/dl

Increased proteinankylosing spondylitisarthritis Crohn diseaseGoutPsoriasisReiter syndromeulcerative colitis.

Chemical Analysis: GlucoseCompare to serum glucose levels

<10 mg/dL lower than blood glucose

Decreased – joint disorders

Chemical Analysis: Uric AcidNormal - 6 to 8 mg/dL

Increased – gout

May form crystals

Chemical Analysis: Lactic AcidRarely measured in synovial fluid

Can be helpful in diagnosing septic arthritis.

Normal = less than 25 mg/dL

Septic arthritis can show levels up to 1000 mg/dL

Laboratory Testing: Lactate DehydrogenaseElevated in synovial fluidNormal in serum level

Increased in Rheumatoid arthritis

(RA)infectious arthritisgout

Neutrophils increased during the acute phase of these disorders contribute to this increased LD.

Laboratory Testing: Rheumatoid FactorRF is an antibody to immunoglobulins.

Present in rheumatoid arthritis:

Serum – most cases

Synovial fluid - 50%

Rarely elevated only in synovial fluid and not serum

False positives in other chronic inflammatory diseases.

Microscopic Analysis: DifferentialLE cells

Neutrophils that have engulfed a nucleus of a lymphocyte

Tart cellsMonocytes that

have engulfed nuclear material

Microscopic Analysis: DifferentialReiter cells

Vacuolated macrophages with ingested neutrophils

RA cells“Ragocytes”Neutrophils with small,

dark, cytoplasmic granules that consist of precipitated rheumatoid factor

Microscopic Analysis: DifferentialHemosiderin

Seen in Pigmented Villonodular Synovitis

Inclusions within clusters of synovial cells

Rice bodiesMacroscopically

resemble polished riceMicroscopically show

collagen and fibrin

Crystal IdentificationMonosodium urate (MSU)

Calcium pyrophosphate (CPPD)

Crystal Identification

Corticosteroid

Cholesterol

Laboratory Testing: Microbiology Staining

Smears prepared by centrifugation or cytocentrifugation

Saline dilution reduces clustering of cells

Gram’s stain most common

Culture

Set up with positive or negative stain results

Aerobicanaerobic

Classification of Joint Disorders

Classification of Joint DisordersGroup Classification Pathologic Significance

1. Noninflammatory Degenerative joint disorders, osteoarthritis

2. Inflammatory Immunologic Disorders, RA, Scleroderma, Polymyositis, ankylylosing spondylitis, rheumatic fever, Lyme arthritis, Crystal-induced gout, pseudogout

Classification of Joint Disorders3. Septic Microbial Infection

4. Hemorrhagic Traumatic injury, tumors, hemophilia, other

coagulation disorders, anticoagulant overdose

Review of Key PointsSynovial fluid analysis

Is a well-established procedure for evaluation of joint disease.

Determines the presence of arthritisAssists in the classification of joint disordersHelps guides appropriate treatments

Thank you