12 Questions
What is the primary importance of macroscopic description of CSF?
To ensure accurate recording of received samples
What is the significance of checking the patient name on all tubes?
To ensure all tubes belong to the same patient
Why are tubes 1 and 3 sent to the biohazard cabinet?
To aseptically load counting chambers
What happens to the supernatant of tubes 1 and 3?
It is sent to biochemistry
Why are two sterile pipettes used?
To take off supernatant and combine remaining samples
What is the approximate percentage of supernatant taken off from tubes 1 and 3?
90%
What is the purpose of sending tube 1 supernatant to biochemistry and tube 2 to cytology?
To test for bacterial and fungal infections
What is the significance of xanthochromia in CSF?
It indicates a recent subarachnoid haemorrhage
Why is it important to perform cell counts on both tubes 1 and 3?
To distinguish between traumatic tap and blood from recent SAH
What does a high protein level in CSF biochemistry indicate?
A more inflammatory and life-threatening condition
Why is it important to record the macroscopic appearance of CSF?
To identify the possible cause of meningitis
What is the purpose of adding toluidine blue dye to a CSF sample?
To distinguish between lymphocytes and polymorphs
Study Notes
Macroscopic Description of CSF
- Importance of accurately recording received CSF samples and their destinations (e.g., tubes 1, 2, and 3 for M, C & S, cytology, and biochemistry)
- Verify patient names on all tubes to ensure correct identification
Processing CSF Samples
- Tubes 1 and 3: cell counts, centrifugation, and supernatant separation for biochemistry
- Tube 2: untouched, sent to cytology
- Combine deposit from tubes 1 and 3 for Gram stain and plate inoculation
- Leave at least one drop of deposit in tube 3
Importance of Macroscopic Appearance
- Record turbidity, bloodstaining, and xanthochromia (yellow-orange color due to broken-down red blood cells, indicating recent subarachnoid hemorrhage)
- Xanthochromia can be detected using a spectrophotometer, and samples should be protected from light
Traumatic Tap vs. Recent SAH
- Traumatic tap: blood from a capillary, detected by comparing cell counts in tubes 1 and 3
- Recent SAH: blood from CSF, no difference in cell counts between tubes 1 and 3
Biochemistry and Cell Counts
- Can indicate possible causes of meningitis, such as:
- Lymphocytes: viral, tuberculous, or yeast (cell-mediated immunity)
- Polymorphs: life-threatening, often with turbid CSF and low sugar levels
- Toluidine blue can help distinguish lymphocytes from polymorphs
This quiz is about the importance of macroscopic description of CSF samples, including recording and labeling of tubes for various laboratory tests.
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