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24-Hour Cerebrospinal Fluid Output Measurement

Published: August 9, 2026Updated: August 16, 2026

This test measures the volume of cerebrospinal fluid (CSF) drained over a 24-hour period from a subarachnoid drain, often used after procedures like spinal surgeries or to monitor conditions affecting CSF flow.

Quick summary

["Assesses fluid balance and potential complications after spinal interventions or neurological conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
9183-5
Short code
Fluid output subarachnoid drain 12h
Synonyms
Fluid output subarachnoid drain 12h
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you’ve had a spinal surgery, spinal procedure, or condition like hydrocephalus (excess CSF in the brain). It helps track how well your body is draining fluid from the spinal area and whether drainage is working properly.

What to Expect Before the Test

You’ll likely have a catheter (subarachnoid drain) in place, and the test involves measuring fluid output collected over 24 hours. No special preparation is needed beyond keeping the drain connected and following your doctor’s instructions.

What the Results Mean

Results help determine if fluid is draining normally. Abnormally low or high outputs could signal issues like blockages, infection, or improper drainage setup. Your doctor will interpret results in relation to your medical history and symptoms.

Potential Risks and Complications

Risks are minimal, but complications like infection at the drain site or improper fluid balance could occur. Your doctor will monitor you closely and adjust care if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CSF Output (24h)

Frequently asked questions

What is a normal range for this test?
There is no single standard range since output varies by individual, procedure, and health status. Your doctor will compare results to your baseline and clinical picture.
How often will I need this test?
Your doctor may repeat this test if you have ongoing symptoms, complications, or if further monitoring is needed after your procedure.
Can I stop the drain before the test?
No, you must keep the drain connected for the full 24-hour period to get accurate results. Follow your healthcare provider’s instructions carefully.
  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 16, 2026. · Read our editorial policy