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Cerebrospinal Fluid (CSF) White Blood Cell Count (Qualitative)

Published: August 9, 2026Updated: August 17, 2026

This test examines the presence and type of white blood cells in your cerebrospinal fluid, often done when you have symptoms like headaches, fever, or neurological concerns.

Quick summary

["A simple check to help identify infections or inflammation in your brain and spinal cord."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
40630-6
Short code
nRBC Bld Ql Smear
Synonyms
nRBC Bld Ql Smear
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

CSF white blood cells can signal conditions like meningitis, brain infections, or inflammatory diseases. The smear helps determine the type and number of cells present, guiding further treatment decisions.

What to Expect Before the Test

You may receive a mild headache or lightheadedness after the procedure, but it usually resolves quickly. Avoid vigorous activity for a few hours afterward.

How the Test Is Performed

A small amount of CSF is collected via a needle inserted into your spine. The sample is then examined under a microscope to count and identify white blood cells.

Possible Results and Next Steps

Results are qualitative (yes/no presence) rather than numeric. Elevated white blood cells may prompt further testing, such as cultures or imaging, to identify the cause.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CSF WBC smear

Frequently asked questions

What does a positive result mean?
A positive result means white blood cells are present in your CSF, which may indicate inflammation, infection, or another condition affecting your brain or spinal cord. Your doctor will discuss next steps based on your symptoms and test results.
How long does it take to get results?
Results are typically available within a few hours to a day, depending on lab processing. Your healthcare provider will share them promptly during your follow-up visit.
Can I eat or drink before this test?
You can eat and drink normally before this test unless instructed otherwise. Since it involves a spinal tap, avoid alcohol or heavy meals that might increase discomfort afterward.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy