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Blast Cells, Cerebrospinal Fluid — Manual Count

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

A laboratory examination of cerebrospinal fluid that counts blast cells, abnormal immature white blood cells, using manual microscopic review.

Quick summary

["Detects blast cells in cerebrospinal fluid to help evaluate possible central nervous system involvement by a blood cancer."]

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

Key facts at a glance

LOINC
13521-0
Short code
Blasts NFr CSF Manual
Synonyms
Blasts NFr 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 (CSF) for blast cells. Blasts are immature or poorly developed white blood cells that are not normally expected to be present in CSF.

Why might I need this test?

A CSF blast count may be used when a blood cancer is suspected, when there are signs of central nervous system involvement, or when monitoring a condition involving the brain and spinal cord. It is generally interpreted together with other laboratory and clinical findings.

How is the test performed?

CSF is usually collected through a lumbar puncture, also called a spinal tap. A laboratory professional then reviews a prepared sample under a microscope and manually counts any blast cells present.

How do I prepare for the test?

No special food or medicine preparation is usually required for the laboratory count itself. If a lumbar puncture is planned, follow your clinician's instructions and tell the care team about medicines, allergies, bleeding problems, or the possibility of pregnancy.

Reference range

Adult: 10-40 U/LN/A

Specimen: csf

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 Count

Frequently asked questions

What does a blast cell mean?
A blast is an immature white blood cell. Mature white blood cells normally present in the blood, but blasts are not normally expected in CSF.
Does this test require a spinal tap?
Yes, the test is performed on cerebrospinal fluid, which is usually obtained through a lumbar puncture. Occasionally, a sample collected for another reason may also be used.
Can a normal result rule out a blood cancer?
No. A result with no detected blasts is reassuring for that specimen, but it does not by itself exclude a blood cancer or central nervous system involvement. Your clinician will interpret the result with your other tests and symptoms.
  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