Cerebrospinal Fluid
Investigation : Cerebrospinal Fluid
CSF will be required for microbiological examination and for protein and glucose estimation. Sufficient CSF will therefore be required for all of these investigations.

A simultaneous sample of blood for glucose estimation must also be sent to aid interpretation.

Investigation Microscopy - Cell count and Gram stain
Culture & sensitivity
Inform lab before sending Yes
Ideal time to take specimen Ideally prior to antimicrobial therapy - although treatment should not be withheld pending investigation
Specimen container
CSF Collection -
1 x yellow-top fluoride EDTA tube (numbered 2)
2 x 28ml sterile universal container (numbered 1 & 3)

Blood collection
1 x grey top fluoride EDTA tube (for blood glucose)

If Virology investigations are required then it necessary to send an additional sample. Approx 1ml in sterile universal container marked 'for Virology'
Labelling requirements Request forms
1 x Clinical Chemistry (GREEN),
1 x Medical Microbiology (BLUE)

Specimen container must have:
  1. Unit number/A&E number or date of birth
  2. Fullname (forename and surname)
  3. Specimen type
  4. Date of collection
Request form must have:
  1. Unit number/A&E number or date of birth
  2. Fullname (forename and surname)
  3. Date of birth
  4. Location
  5. Specimen type
How to take specimen & Volume required Specimens must be collected sequentially.

  • Collect the first 2.5ml of CSF in the 28ml sterile universal container (numbered 1) for Medical MIcrobiology, followed by
  • A minimum of 0.5ml in the yellow top fluoride EDTA tube (numbered 2) for glucose and protein estimations follwed by
  • Approximately 2.5ml in the sterile universal container (numbered 3) also for Medical Microbiology
1. If TB is suspected collect 5 to 10ml of CSF in a sterile universal container.
Transport to the laboratory CSF samples 1 & 3 (and any sample for Virology) to be placed in Medical Microbiology specimen bag (with completed request form) and dispatched immediately via the pneumatic tube system.

CSF samples 2 and blood sample to be placed in Clinical Chemistry specimen bag (with completed request form) then this specimen bag MUST be delivered by hand to Clinical Chemistry as soon as possible (within 30 minutes).
Turnround Results within 2 hours of receipt
Reference range - normal
Appearance Cell count
Gram stain Glucose Protein
Clear 0-5 lymphocytes No organisms seen See Glucose (CSF) See Protein (CSF)
This table is is intended as a general guide only. For interpretation of results and advice please contact the medical team in the Microbiology department.
Additional Information Relevant clinical information including a brief description of symptoms; possibility of TB, presence of known virus infections should be included on the request form to ensure appropriate investigations are performed.

See also under Meningitis.

For information on xanthochromia analysis click here.

Specimen retention Please ensure that any requests for additional investigations on the specimen are made within 7 days from the date of the original request


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