12 Questions
What is the primary importance of macroscopic description of CSF samples?
To record exactly what is received and where it goes
Why is it essential to inspect the tubes before processing?
To ensure the tubes are properly labelled
What is the purpose of loading two counting chambers in the biohazard cabinet?
To perform cell counts on tubes 1 and 3
What is the purpose of taking off the supernatant from tubes 1 and 3?
To prepare the samples for biochemistry
What is the significance of the centrifugation step in the process?
To separate the supernatant from the remaining sample
What is the rationale behind taking the remainder from tube 1 to combine with tube 3?
To prepare the samples for biochemistry
What is the significance of xanthochromia in CSF?
It suggests a recent subarachnoid haemorrhage
Why is it important to perform cell counts on both tubes 1 and 3?
To identify a traumatic tap
What is the purpose of adding CSF to a tube coated with dry toluidine blue dye?
To differentiate between lymphocytes and polymorphs
What is the significance of a low sugar level in the CSF?
It suggests a bacterial or fungal infection
What is the rationale for recording the macroscopic appearance of CSF?
To differentiate between a traumatic tap and a recent SAH
Why is it important to protect the CSF sample from light during biochemical investigation of xanthochromia?
To prevent interference with the spectrophotometer reading
Study Notes
Describing CSF Samples
- A macroscopic description of CSF is crucial and should include recording exactly what is received and where each tube goes.
- For a CSF requesting M, C & S, cytology, and biochemistry, record 3 tubes of 1 ml each, with Tube 2 sent to cytology, and cell count and supernatant sent to biochemistry.
Processing CSF Samples
- Inspect tubes for clarity and perform cell counts on tubes 1 and 3.
- Aseptically load 2 counting chambers, one for tube 1 and one for tube 3, and centrifuge the tubes.
- Take off the supernatant (around 90%) from tubes 1 and 3, combine the remainder, and send tube 1 supernatant to biochemistry and tube 2 (untouched) to cytology.
Macroscopic Appearance of CSF
- Record the volume of CSF received in each tube, turbidity, bloodstaining, and xanthochromia.
- Xanthochromia is a yellow-orange color of the supernatant, indicating a recent subarachnoid hemorrhage (SAH).
- A traumatic tap is when a capillary is hit during lumbar puncture, causing blood in the CSF, and can be differentiated from SAH by performing cell counts on both tubes 1 and 3.
Biochemistry and Cell Counts in Meningitis
- Biochemistry and cell counts can help identify the cause of meningitis, such as viral, bacterial, or fungal infections.
- Lymphocytes may indicate viral, tuberculous, or yeast infections, while polymorphs indicate life-threatening infections.
- CSF biochemistry can show low sugar levels, indicating bacterial or fungal consumption, and increased protein levels, indicating more severe inflammation.
Learn about the importance of accurately recording and handling CSF samples, including macroscopic description and distribution of samples for various laboratory tests.
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