From the Guidelines
The CSF cell count should be performed using the tube 1 specimen, which is collected in a sterile tube without additives, to ensure the most accurate representation of cells present in the cerebrospinal fluid. When performing a lumbar puncture, multiple tubes are collected sequentially, with tube 1 being the first tube collected. This tube is used for cell count and differential because it contains the most accurate representation of cells present in the cerebrospinal fluid. The cell count should be performed promptly (within 1-2 hours of collection) to prevent cellular degradation which can affect results, as noted in guidelines for CSF analysis 1. The normal CSF cell count in adults is 0-5 white blood cells per cubic millimeter, with no red blood cells. Higher counts may indicate infection, inflammation, or bleeding. The reason tube 1 is used rather than subsequent tubes is that any traumatic tap (where blood is introduced during the procedure) will typically show decreasing red blood cell counts in sequential tubes, helping differentiate between a true subarachnoid hemorrhage and a traumatic tap.
Key considerations for CSF cell count include:
- Prompt analysis to prevent cellular degradation
- Use of tube 1 for the most accurate representation of cells
- Normal CSF cell count in adults is 0-5 white blood cells per cubic millimeter
- Higher counts may indicate infection, inflammation, or bleeding, and should be interpreted in the context of clinical presentation and other diagnostic findings, as discussed in the management of encephalitis 1.
It is also important to note that while CSF cytology can be used to diagnose leptomeningeal metastases, false-negative results can occur, and guidelines recommend withdrawing at least 10 to 15 mL of CSF for cytologic analysis and repeating the procedure at least once if initial cytology is negative 1. However, this is not directly relevant to the question of which tube to use for CSF cell count.
From the Research
CSF Cell Count Tube
- The CSF cell count is typically performed on a sample collected in an EDTA tube 2.
- EDTA is used as an anticoagulant to prevent clotting and preserve the cells in the sample.
- However, it's worth noting that the choice of tube (EDTA or plain) does not significantly affect the results of the standard CSF analysis, including cell count and differential cell counts 2.
Considerations for CSF Collection
- When collecting CSF, it's essential to follow proper procedures to avoid contamination and ensure accurate results.
- The collection of CSF into EDTA tubes does not influence the result of the standard CSF analysis, but a presumed positive effect of EDTA on cell preservation could not be shown in one study 2.
- In some cases, such as suspected bacterial meningitis, additional tests like Gram's stain, culture, and Limulus lysate assay may be performed on the CSF sample 3.
Standard CSF Analysis
- Basic studies of CSF that should be performed in all patients with meningitis include measurement of pressure, cell count and white cell differential, determination of glucose and protein levels, Gram's stain, and culture 3.
- The analysis of CSF allows an evaluation of inflammatory processes circumscribed to the CNS and reflects changes in the immunological pattern due to the progression of the pathology, being fundamental in the diagnosis and monitoring of diseases like multiple sclerosis 4.