UA Unit #3

Describe how CSF fluid is formed?

selective filtration of plasma though Chroid plexus capillaries. Active transport secretion by epithelial membrane

List major functions of CSF?

Provides nutrients to nevous tissue, removes metabolic waste, maintains intracranial pressure, mechanical barrier to cushion brain and spinal cord

Between which lumbar vertebrae is a lumbar puncture performed?

3-4 and 4-5

CSF Tube 1

Chemistry/Serology. Least affected by blood or bacteria from tap

CSF Tube 2

Microbiology. Needle has passed already reducing contaminant of skin flora

CSF Tube 3

Hematolgy. Least likely to contain cells introduced by puncture

CSF Hematology Storage

fridge for 4 hours. Must preform cell count within an hour

CSF Microbiology Storage

RT. Don’t put in fridge, inhibits organsims

Chemistry/Serology CSF Storage

Frozen. Protects labile analytes

If only one tube of CSF is obtained which department gets it?

Microbiology

Why might a cell count be ordered on both the first tube collected and the last tube rather than on just one tube?

The first tube is most liekly to have RBC. As more tube are drawn there will be less RBC in each tube

Xanthochromic

pink, orange, yellow. RBC degranulation.

Hemolyzed/Bloody CSF

hemorrhage or traumatic tap

Cloudy CSF

infection

Milky CSF

lipids or proteins

Define xanthochromia and at least three possible causes besides RBC degredation

A pink,orange,yellow color of CSF.

Increased serum bili, increased protein, and carotene pigment

CSF Traumatic Tap

uneven blood, heaviest in tube #1.

May clot (fibrinogen introduced in tap)

Clear supernatant after centrifugation

Intracranial Hemorrhage

Blood even across all tubes

No clot present

Xanthochromic supernatant after centrifugation

Why is a Xanthochromic supernatant generally NOT seen immediately following a traumatic tap?

RBC require 2 hours to degrade. In true hemmorhage they have time to break, this does not happen in traumatic tap

A web-like pellicle forms in a CSF specimen after overnight refrigeration, what condition is this?

TB meningitis

What additional rapid test could further support the presence of a true hemorrhage?

D-Dimer

What additional microscopic finding, if present, would further support a true hemorrhage?

Erythrophagocytosis. Macrophage contain ingested RBC (hemosiderin)

Adult CSF WBC Count

0-5

Neonate CSF WBC Count

Less than or equal to 30

Why have electronic cell counters traditonally been avoided for CSF cell counts, even though automated body-fluid analyzers are increasingly used today?

Traditional automated counters have high background counts and poor reproducibility at low concentrations

Why must a CSF differential be performed on a concentrated, stained smear rather than directly from cells seen in counting chambers?

Cells are poorly visualized and easily distorted risking overlooking abnormal cells

Describe the principle of cytocentrifugation

Forces cells onto a slide monolayer, positive charged slides attracts cells

Why use albumin during cytocentrifugation?

It increases cell yield and decreases cellular distortion

Predominant Neutrophils in CSF

Bacterial meninigits

Predominant lymphocytes and monocytes in CSF

Viral, tubercular, or fungal meningitis

Increased eosinophils in CSF

Parasitic infection, fungal infection, or introduction of foreign material

Increased macrophages containing hemosiderin in CSF

Previous hemorrhage

Nucleated RBC in CSF

Bone marrow contamination introduced by the puncture

Clusters of choroidal, ependymal, or spindle-shaped cells in CSF

Nonpathologically significant

Explain why CSF glucose is normally lower than plasma glucose?

60-70% of plasma glucose. Due to selective transport across blood-brain barrier

Why must the timing of blood glucose draw be coordinated with lumbar puncture for an accurate CSF glucsoe?

The blood glucose should be drawn approximately 2 hours before the spinal tap to allow time for equilibration between the blood and CSF, so that a valid comparison between the two values can be made

Bacterial Meningitis findings

Neutrophils, Decreased glucose, increased protein, greater than 25 lactate

Viral meningitis Findings

lymph/monocytes, normal glucose, normal to increased glucose, less than 25 lactate

Tubercular Meningitis Findings

lymph/monocytes. Decreased glucose, increased protein, and greater than 25 lactate

Fungal Meningitis Findings

lymph/monocytes. Decreased glucose, increased protein, and greater than 25 lactatess

A severely hemolyzed RBC CSF specimen is submitted for lactate testing, what will happen?

RBC contain high concentrations of lactate, so there will be a false pos

Name the CSF protein fraction that is second most prevalent (after albumin)?

Transthyretin

Name the fraction that is unique to CSF and useful for confirming a fluid is CSF?

Tau

Name three pathological conditions associated with an elevated CSF total protein

meningitis, syphillis, tumors, etc.

Explain the purpose of the CSF/serum albumin index

Evaluates the integrity of blood brain barriers. Less than 9 indicates it’s intact

How does the CSF IgG index differ from that of the CSF/serum albumin index?

IgG enters blood brain barrier because of damage. Greater than .70 indicates IgG production in CNS

CSF/Serum Albumin formula

CSF albumin / serum albumin

IgG index Formula

Step 1: CSF IgG / Serum IgG = X

Step 2: X / (CSF/Serum albumin)

What is the primary role of microbiology laboratory in CSF?

To ID causative agent of meningitis

Why is the CSF typically centrifuged (or cytocentrifuged) before performing a gram stain?

To concentrate specimen since only a small # of organism are present

Strep pneunmo

Gram pos diplococci (lacnet shape)

General adult population

H. influenzae

Pleomorphic gram-negative rods/coccobacilli

Children

N. meningitidis

Gram neg diplococci

Adolescents / Young Adults

E. Coli

Gram neg rods

Neonates

L. monocytogenes

Gram pos rods

Neonates, immunocompromised patients

Which fungal organism is classically detected using an India Ink preparation, what what specific finding on gram stain should tech watch for?

Cryptococcus neoformans. Starburst on gram stain, india ink pos too

Common cause of false pos cryptococcal antigen latex agglutination test?

Rheumatoid factor interference

Naegleria fowleri

found in warm ponds, lakes, and pools. Brain eating ameoba that enters via nasal cavity

Which serological test is recommended by the CDC for diagnosing neurosyphilis in CSF?

VDRL. FTA-ABS has a higher risk of false pos

List three functions of synovial fluid?

Lubrication for movable joints, nutrients for articular cartilages, and lessens shock of joint compression

Explain how synovial fluid is formed and why its viscous?

It’s an ultrafiltrate of plasma across the synovial membrane. No high weight molecules. Synoviocytes in membrane secrete hyaluronic acid - makes fluid viscous

Hematology Tube for Synovial Fluid

Liquid EDTA b/c it prevents clots

Microbiology Tube for Synovial Fluid

Sterile heparinized b/c it maintains sterility

Crystal Examination Tube for Synovial Fluid

Heparin or liquid EDTA. powdered and acetic acid form artifact crystal

Chemistry Tubes for Synovial Fluid

Sodim Fluoride b/c it prevents glycolysis

Why must synovial fluid testing be performed ASAP after collection, what should you do if delay is innevitable?

To avoid cellular lysis and any changes in crystals. Refrigerate the specimen if delay is inevitable

Name the procedure to collect synovial fluids?

Needle Aspiration (Arthocentesis)

Volume of fluid in a normal knee vs inflamed knee

Normal is 3.5mL inflamed is greater than 25mL

Powdered anticoagulant or acetic-acid containing dilutent used

Artifact crystal

Specimen for cell count left at RT for an extended time

Cellular lysis. Decreased cell count

Glucose specimen not analzyed within 1 hour or preserved with sodium fluoride

Glycolysis and false decreased glucose

Cystal examination delayed or specimen exposed to temperature/pH change

Crystal may change. Decrease or wrong crystal ID

Cell count tube collected without anticoagulant

Fibrinogen containing fluid from diseased joint can clot making cell count impossible

Describe the color and clarity of normal synovial fluid

colorless to pale yellow. Egg white consistency

Deep yellow, clear to slightly cloudy synovial fluid

non-inflammatory or inflammatory effusion

milky/turbid synovial fluid

crystal induced

Uneven streaky bloody synovial fluid

Traumatic tap

uniform, diffuse bloody synovial fluid

hemorrhagic

Green tinged synovial fluid

Infection

What causes turbidity in synovial fluid, and what simple bedside test is used to asses viscosity at time of collection?

WBC, cellular debris, fibrin, crystal, fat droplet, synoviocytes

How does the mucin clot (Ropes) test work and how are results reported

Add 2-5% acetic acid to form clot

Good = Soft Clot

Fair = soft clot

Poor = friable or no clot

Why cant acetic acid-based diluting fluid traditionally used for body fluid WBC counts be used for a synovial fluid WBC?

Acetic acid causes mucin clot to form interfering with cell count. Use normal saline/methylene blue

What WBC count is considered normal for synovial fluid, and what differential percentages define the upper limits for neutrophil and lymphocyte?

Normal is less than 200 cells

N: <25%

L: <15%

Why is synovial fluid typically incubated hyaluronidase before performing a cell count for preparing differential slide?

Hyaluronidase breaks down viscous hyaluronic acid which interferes with cell count

A differential shows a marked increase in neutrophils. What does this suggest, versus a differential with an elevated cell count but a predominance of lymphocytes?

Sepsis vs a non-septic infection

Ragocytes (RA cells)

Neutrophils containing small, dark cytoplasmic granules of precipitated rheumatoid factor

Reiter Cells (neutrophages)

Vacuolated macrophages containing ingested neutrophil

LE Cells

Neutrophils that have phagocytized denatured nuclear material, classically assocated with systemic lupus erythrematosus

Lipid Droplets

Fat globules associated with a crush injury to the joint

Hemosiderin Granules

Hemoglobin breakdown product seen in the cases of pigmented villonodular synovitis

Noninflammatory Synovial Fluid

Clear yellow

WBC <1000

Neutrophil <30%

Inflammatory Synovial Fluid

Cloudy yellow fluid

WBC <1000

Neutrophil: >50%

Decreased glucose level

Septic Synovial Fluid

Cloudy, yellow-green fluid

WBC up to 100,000

Neutrophi <70%

Decreased glucose and crystals present

Hemorrhagic Synovial Fluid

Cloudy red

WBC equal to blood

Neutrophils equal to blood

A joint fluid specimen shows uneven, streaky blood on visual inspection

Indicative of a traumatic tap

Monosodium Urate (MSU)

Needle shaped, yellow when parallel. Neg birefringence. Gout. Fast ray impeded

Calcium Pyrophosphate Dihydrate

rhombic, square shape, rods. Blue. Pos birefringence. Psuedogout. Fast ray passes

Hydrooxyapatite Crystal

cartilage degeneration and electron microscopy

Cholesterol Crystal

systemic autoimmune disease and notched corners

Corticosteroid Crystal

injections. flat, variable plates