Question

The cell count is low on a central nervous system fluid sample and needs to be concentrated for proper analysis. Which method is the most common for concentrating this sample?

1) Low-speed centrifugation
2) Membrane filtration
3) Gravitational sedimentation
4) Cytocentrifugation

Answer 1

Cytocentrifugation is the most common method for concentrating cells in CNS fluid samples such as CSF for microscopic analysis and is standardized for various neurological diagnoses.

Step-by-step explanation:

For concentrating a sample of central nervous system fluid (CNS fluid) such as cerebrospinal fluid (CSF), the most common method used is cytocentrifugation. This technique involves centrifuging a fluid sample at low to moderate speeds to concentrate cells at the bottom of a tube. The sediment is then used for microscopic analysis. This procedure is standardized and widely utilized for diagnosis of various neurological diseases and conditions by analyzing cell counts and microorganism presence in the fluid.

The other methods mentioned like low-speed centrifugation are also possible but less frequently used for CSF samples where cell adhesion to slides after the spin is important. Membrane filtration may be used for samples like water to concentrate microorganisms before plating. Gravitational sedimentation is rarely used due to its low efficiency for cell sample concentration.