The CSF medical abbreviation most often means cerebrospinal fluid, the clear, watery liquid that surrounds and cushions the brain and spinal cord. Doctors sample it, usually with a lumbar puncture, to look for infection, bleeding, inflammation and some cancers of the nervous system.
In cancer and blood care, CSF can also mean colony stimulating factor, a type of medicine that boosts white blood cell production. This page explains what cerebrospinal fluid does, how a CSF analysis reads, and how to sort out which one a note intends.
At a glance
Stands for
Cerebrospinal fluidOther meanings
Colony stimulating factor (oncology, as in G-CSF)Made by
The choroid plexus, tissue inside the brain's ventriclesCollected by
Lumbar puncture (spinal tap), sometimes a drainNormal look
Clear and colorlessUsed in
Neurology, infectious disease, neurosurgery, oncology
What cerebrospinal fluid does
CSF fills the hollow spaces inside the brain, called ventricles, and the narrow space around the brain and cord. It works as a shock absorber, keeps the brain buoyant, and carries away waste. The body makes it continuously, roughly a pint each day, and reabsorbs it at about the same rate, so only a small amount is present at any one time.
When flow or absorption is blocked, fluid can build up, a problem called hydrocephalus. Changes in the pressure of this fluid are measured as intracranial pressure.
How the CSF medical abbreviation appears in test results
The sample is usually taken through a lumbar puncture, a thin needle placed between the bones of the lower back. Several tubes are filled and sent for different tests.
| Test | What it looks for |
|---|---|
| Appearance | Clear, cloudy, bloody or yellow tinged |
| Opening pressure | Fluid pressure measured at the start |
| Cell count | White and red blood cells |
| Protein | Raised in infection, inflammation and some nerve disorders |
| Glucose | Often low in bacterial infection |
| Gram stain and culture | Bacteria under the microscope and grown in the lab |
Extra tests may look for viruses, antibodies or abnormal cells, depending on the question.
Reading a sample note
Neurology note: "LP: CSF clear, WBC 2, RBC 0, protein 38, glucose 62. Gram stain negative." The fluid looked normal, with very few cells, normal protein and glucose, and no bacteria seen. That pattern makes a bacterial infection unlikely, although final cultures take longer.
When bleeding has occurred near the brain surface, as in a subarachnoid hemorrhage, the fluid may contain red cells or turn yellow, a change called xanthochromia. Exact reference ranges vary by lab and by age.
Colony stimulating factor in oncology
In cancer care notes, CSF usually appears as part of a longer term such as G-CSF, granulocyte colony stimulating factor. These medicines, such as filgrastim, help the bone marrow make white blood cells after chemotherapy. A note might read "G-CSF support after cycle 2" or list an absolute neutrophil count, ANC, beside it.
| Meaning | Setting | Typical companions |
|---|---|---|
| Cerebrospinal fluid | Neurology, infection workup, neurosurgery | LP, opening pressure, protein, glucose |
| Colony stimulating factor | Oncology, hematology | G-CSF, neutropenia, chemotherapy cycle |
CSF leaks and drains
A small amount of fluid can leak after a spinal tap, which may cause a headache that is worse when sitting up. Leaks can also follow injury or surgery and sometimes show as clear fluid from the nose. In intensive care, an external ventricular drain removes fluid and measures pressure. More test shorthand sits under the hub for lab and scan terms.
Questions to ask about a spinal fluid test
- What question is this sample meant to answer?
- Which results are back now and which take longer?
- How should I rest after the procedure, and what symptoms should I report?
- If CSF is mentioned in my cancer care, does it refer to a medicine?
Spinal fluid findings are read together with your symptoms and other tests. Your neurologist or the team caring for you can explain what your results mean.
Frequently asked questions
What is CSF short for?
Usually cerebrospinal fluid, the liquid bathing the brain and spinal cord. In cancer care it can stand for colony stimulating factor, a medicine that raises white blood cell counts.
How is CSF collected?
Most samples come from a lumbar puncture, a needle placed in the lower back that many people call a spinal tap. In some hospital patients it is taken from a drain already in place.
What does clear CSF mean?
Clear, colorless fluid is the normal appearance. Cloudy fluid can suggest infection, and pink or yellow fluid can suggest blood, though lab results decide what it means.
Is a CSF leak serious?
A small leak after a spinal tap often settles on its own, but some need treatment. Anyone with ongoing headache, clear nasal drainage or fever after a procedure should contact their care team.