Blast Cells, Cerebrospinal Fluid — Manual Differential Count
A manual microscopic examination of cerebrospinal fluid that identifies and counts immature blast cells, often used to assess possible central nervous system involvement by leukemia.
["This CSF test looks for blast cells, which are immature blood cells that may indicate leukemia involving the nervous system."]
Key facts at a glance
- LOINC
- 71656-3
- Short code
- Blasts NFr.DF CSF Manual
- Synonyms
- Blasts NFr.DF CSF Manual
- Category
- liver
- Sample
- csf
- Container
- Sterile tube
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- manual-count
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test examines cerebrospinal fluid, the fluid surrounding the brain and spinal cord, for blast cells. Blast cells are immature blood cells that are not normally present in cerebrospinal fluid. A manual differential count means a laboratory specialist reviews the fluid under a microscope to identify and count these cells.
Why might I need this test?
The test may be ordered when a person has signs or symptoms suggesting that leukemia or another blood-forming disorder may involve the brain or spinal cord. It can also help evaluate cerebrospinal fluid in people who have already been diagnosed with blood cancer.
How is the test performed?
Cerebrospinal fluid is usually collected through a lumbar puncture, also called a spinal tap. A clinician inserts a needle into the space around the lower spinal cord, and the fluid is sent to the laboratory. A technologist then prepares and reviews the specimen under a microscope to identify blast cells and other cell types.
How do I prepare for the test?
Follow the instructions provided by the clinician or laboratory. You may be asked to avoid certain medicines that could affect blood-cell findings, but medicines should not be stopped without medical advice. Tell the care team if you have bleeding problems, take blood thinners, or have had back surgery or a lumbar puncture recently.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CSF Blast Cell Count
Frequently asked questions
Is this the same as a routine spinal tap?
Does the test tell me whether I have leukemia?
Will the spinal tap be painful?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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