Training course CSF processing in medical laboratory - Lecture 01 Hussein A. Abid

1. INTRODUCTION, COLLECTION
AND STORAGE
Hussein A. Abid
Laboratory Medicine Specialist
Iraqi Medical Laboratory Association
Scientific Affairs and Cultural Relations Section
Scientific Affairs and Training
First lecture
23/09/2018 (Sunday)

2. CEREBROSPINAL FLUID (CSF)
• Clear, plasma-like fluid surrounding the brain in the
skull and the spinal cord in the spinal column.
• Secreted by choroid plexus of ventricles (~500 ml/day).
• Circulates in ventricles, central canal of spinal cord,
and subarachnoid space.
• Total volumes:
 Adults: 140 - 170 mL
 Children: 10 - 60 mL
Cerebrospinal Fluid (CSF) Processing In Medical Laboratory
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3. CEREBROSPINAL FLUID (CSF)
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4. CEREBROSPINAL FLUID (CSF)
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5. CEREBROSPINAL FLUID (CSF)
CSF functions:
• To protect the brain and the spinal cord from injury
by acting as a fluid cushion.
• It carries nutrients to the brain and spinal cord and
removes waste products.
• It is important to maintain a constant pressure
inside the head and around the spinal cord.
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6. Flow of cerebrospinal fluid (CSF) 6

7. CEREBROSPINAL FLUID (CSF)
• Blood brain barrier (BBB) maintains the relative
homeostasis of CNS environment by tightly regulating
the concentration of substances by specific transport
systems for H+, K+, Ca+2, Mg+2, HCO-3.
• Glucose, urea and creatinine diffuse freely between
blood and the CSF.
• Proteins cross freely by passive diffusion along the
concentration gradient
• CSF helps maintain stable ion concentrations in central
nervous system (CNS).
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8. Molecules and ions movement 8

9. 9
NORMAL CSF CONTENTS
UnitNormal rangeSubstance
mg/ dL50 – 80Glucose
mg/ dL15 – 45Protein
mg/ dL6.0 – 16Urea
mg/ dL0.5 – 3.0Uric acid
mg/ dL0.6 – 1.2Creatinine
mg/ dL0.2 – 0.6Cholesterol
µg/ dL10 – 35Ammonia
mEq/ L135 – 150Sodium
mEq/ L2.6 – 3.0Potassium
mEq/ L115 – 130Chloride
mEq/ L2.4 – 3.0Magnesium
Lymphocyte/ µL0 – 5Cells (WBCs)
Cerebrospinal Fluid (CSF) Processing In Medical Laboratory

10. NORMAL CSF CHARACTERISTICS
UnitNormal rangeSubstance
ColorlessColor
ClearAppearance
No clot formation on
standing
Clot
7.28 – 7.32pH
g/ mL1.003 – 1.004Specific gravity
g/ dL0.85 – 1.70Total solids
mmHg40 – 44P O2
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11. CSF ANALYSIS
• Cerebrospinal fluid (CSF) analysis is a set of
laboratory tests that examine a sample of the fluid
surrounding the brain and spinal cord.
• Routine examination of CSF includes visual
observation of color and appearance and tests for
glucose, protein, lactate, lactate dehydrogenase
(biochemical testing), red blood cell count, white
blood cell count and other cytological tests in
addition to microbiological testing for bacteria,
parasites and/or viruses.
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12. CSF ANALYSIS
The purpose of CSF analysis is to investigate
certain conditions such as:
• Infections such as meningitis or other bacterial,
viral or parasitic infections.
• Inflammation or autoimmune disorders such as
multiple sclerosis.
• Bleeding in the brain and spinal cord, or
• Metastatic tumors (e.g., leukemia).
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13. CSF SAMPLE
• The amount of CSF needed is 15 – 20 mL.
• The CSF should be collected by lumbar puncture.
• Primary care physicians frequently perform lumbar
puncture, because CSF is an invaluable diagnostic
window to the central nervous system (CNS).
• Lumbar puncture (LP) is performed by inserting the
needle between the fourth and fifth lumbar vertebrae
(L4-L5). This location is used because the spinal cord
stops near L2, and a needle introduced below this
level will miss the cord.
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14. 14

15. LUMBAR PUNCTURE
Contraindications:
• Presences of increased intracranial pressure (ICP), regardless of
cause, can increase risk of cerebral or cerebellar brainstem
herniation at the level of the foramen magnum.
• Use of anticoagulants (e.g., warfarin, enoxaparin, etc.) due to
increased risk of developing an epidural hematoma.
• Evidence of cellulitis or abscess over the area where LP would
be performed due to risk of introducing infection into the
subarachnoid space.
• Significant degenerative joint disease or prior back surgeries
where hardware maybe in place (Note: many of these patients
may require an LP under fluoroscopy)
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16. LUMBAR PUNCTURE
Risks:
• In some circumstances, a lumbar puncture to withdraw
a small amount of CSF for analysis may lead to serious
complications.
• Lumbar punctures should be performed only with
extreme caution, and only if the benefits are thought to
outweigh the risks.
• In people who have bleeding disorders, lumbar
puncture can cause hemorrhage that can compress
the spinal cord.
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17. LUMBAR PUNCTURE
Most common complications:
1. Herniation of the brainstem.
2. Accidental puncture of the aorta or vena cava leading to
retroperitoneal hematoma.
3. Accidental puncture of the spinal cord from being in wrong
location.
4. Infection being introduced into the subarachnoid space.
5. Pain over the LP site.
6. Headache from CSF leak.
7. Can worsen with sitting up or standing, and if lasting longer than
1-2 days may require a blood patch in the area of the LP
puncture site.
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18. LUMBAR PUNCTURE
Before the procedure:
• Verify that no contraindications exist.
 This may include doing a computed tomography (CT)
head to rule out active bleeding, midline shift, space-
occupying lesions or signs of brain swelling.
• Explain the procedure to the patient and answer all
questions.
• Obtain informed consent with appropriate documentation.
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19. LUMBAR PUNCTURE
Before the procedure:
• Do a baseline neurologic exam with special
notation on the strength, sensation and ability to
move extremities.
• Place the necessary orders so that the CSF tubes
can be labeled after the procedure is completed.
• Wash hands, open the lumbar puncture tray
without compromising sterility and consider any
extra supplies (i.e., spinal needles or extra tubes).
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20. LUMBAR PUNCTURE
During the procedure:
• Position the patient either in lateral decubitus/fetal position, or sitting
upright leaning forward over a small table.
 Opening pressures cannot be obtained accurately if the patient is
upright.
 If opening pressures are indicated, the patient will need to straighten
out after insertion of the needle to accurately measure the opening and
closing pressure, because they can be falsely increased with the
pressure applied to the abdomen in a fetal position.
• Locate the L3/L4 space by locating the superior iliac crests and placing
your thumbs midline to the spine. Palpate above and below to determine
the widest space and attempt to mark location with the nail of your thumb
or create a small indentation with an object like pen or needle cap.
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21. LUMBAR PUNCTURE
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22. LUMBAR PUNCTURE
During the procedure:
• Aseptically clean the skin using chlorhexidine skin prep.
 Some clinicians will do this using the skin prep provided
in the LP tray once they have their sterile gloves on.
• Put on sterile gloves, facemask, and protective gear per
institutional policy.
• Finish setting the LP tray including opening the CSF tubes
in preparation to be easily accessed, and apply the sterile
drapes to the patient.
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23. LUMBAR PUNCTURE
During the procedure:
• Draw up and inject 10 mL of 1% or 2% lidocaine (preservative free;
without epinephrine) to the area.
• Consider injecting some anesthetic a level above or below this area in
case an adjustment is needed
• Insert the spinal needle directed at a slight cephalad angle (imagine
aiming towards the umbilicus) and with the bevel of the needle oriented to
the longitudinal fibers in attempt to separate the fibers instead of cutting
them
 If the patient is lying in lateral decubitus position the bevel should be
oriented up.
 If the patient is sitting upright and leaning forward the bevel should be
oriented to the left or right.
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24. LUMBAR PUNCTURE
During the procedure:
• The entry into the subarachnoid space is commonly described as feeling
a "pop" sensation, the needle insert (obturator) is then removed and CSF
should begin to drip out.
• Have the patient slowly stretch out legs (if lying in lateral decubitus).
• Attach the sterile manometer to the end of the spinal needle to
measure the opening pressure:
 Normal opening pressures: < 20 cm H2O
 Measuring opening pressure is very important for evaluation for
cryptococcal meningitis or pseudotumor cerebri.
 If blockage of CSF flow to the spinal subarachnoid space is suspected,
the clinician may perform a Queckenstedt-Stookey test.
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25. LUMBAR PUNCTURE
During the procedure:
• Empty the manometer into CSF tube #1 and about
10 drops of CSF into tubes #2 – 4 (note: some
institutions use only 3 tubes).
• Measure the closing pressure (if indicated).
• Reinsert the needle insert (obturator) and withdraw
the spinal needle and immediately apply pressure
and an adhesive bandage over the insertion site.
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26. LUMBAR PUNCTURE
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27. LUMBAR PUNCTURE
After the procedure:
• While the traditional teaching is to have the patient remain lying
flat after a procedure, there is no evidence that it has any effect on
the development of post-LP headache. At the same time, there is
no harm in having the patient lie flat if they desire to do so.
 Despite the lack of evidence, some clinicians will have the patient lay
prone with a pillow under the abdomen to increase the pressure on the
tissues around the area of the LP in the thought that it might prevent
CSF leaking.
• While based on expert opinion only, some clinicians will
encourage and counsel the patient to drink extra fluids to help
replace the CSF drained off and prevent a headache (or give the
patient IV fluids if warranted)
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28. LUMBAR PUNCTURE
After the procedure:
• Immediately label the CSF tubes have the tubes hand
carried/delivered to the lab for analysis.
• If meningitis is suspected, initiate empiric antibiotics
with or without steroids based on the clinical scenario.
• Repeat neurologic assessment to evaluate for any
changes post-LP.
• Document the procedure, number of attempts, opening
and closing pressure (if applicable), total amount of
CSF drained.
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29. LUMBAR PUNCTURE
Counseling Points:
• Before the procedure, no fasting needed.
• During the procedure, encourage the patient to not
move and try to remain calm.
• After the procedure, encourage fluid intake to
prevent headache and consider resting and lying
flat for first 12 hours to help prevent possible
headaches while things heal.
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30. LUMBAR PUNCTURE
Counseling Points:
• The collected specimen of CSF to be dispatched
promptly to laboratory, delay may cause death of
delicate pathogens (e.g., Meningococci and
disintegrate the leukocytes).
• It is important when there is delay in transportation of
specimens to laboratory DO NOT keep in refrigerator,
which tends to kill H. influenza. (microbiology tube)
• If delay is anticipated leave at room temperature.
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31. LUMBAR PUNCTURE
Cerebrospinal Fluid (CSF) Processing In Medical Laboratory
Don’t keep in refrigerator
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32. CSF TUBES IN BRIEF
• Approximately 15 – 20 mL fluid collected.
• Process within 1 hour without refrigeration.
• Three tube set-up:
 Tube 1: Chemistry and Immunology (frozen)
 Tube 2: Microbiology (room temperature)
 Tube 3: Cell count, differential, cytology (refrigerated)
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