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Serum or Plasma Oxygen Saturation (via Pulse Oximetry)

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

This test measures how much oxygen is bound to hemoglobin in your blood, typically done using a finger or ear sensor. It reflects oxygen levels in arterial blood and is commonly used to assess breathing efficiency.

Quick summary

["Helps monitor oxygen levels quickly and safely during routine or specialized care."]

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

Key facts at a glance

LOINC
2711-0
Short code
SaO2 % BldV
Synonyms
SaO2 % BldV
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

How This Test Works

A small sensor is placed on your finger, toe, or ear lobe. It uses light to measure the oxygen saturation of your blood, providing a quick result. This method is non-invasive and painless.

When You Might Need This Test

Your healthcare provider may order this test if you have symptoms like shortness of breath, fatigue, or if you’re at risk for low oxygen levels, such as during surgery, sleep studies, or monitoring chronic conditions like heart or lung disease.

What to Expect Before the Test

No special preparation is needed. You may be asked to remove jewelry or clothing from the testing area. If you’re taking blood (for other tests), your provider will coordinate timing to avoid delays.

Possible Results and Next Steps

Results are usually available immediately. Normal values vary by age and health status, but a reading below 95% may indicate potential issues like poor breathing, heart problems, or anemia. Your provider will discuss findings with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

O₂ Saturation

Frequently asked questions

Why does my provider want to check my oxygen saturation?
Your provider may need this test to check how well your body is getting enough oxygen, especially if you have symptoms like dizziness, rapid breathing, or fatigue. It’s also useful before certain procedures or during ongoing health management.
What if my oxygen saturation is low?
A low reading could signal a temporary issue (like breathing problems) or a chronic condition. Your provider will work with you to determine the cause and recommend next steps, which may include adjusting medications, improving breathing techniques, or further testing.
Can I eat or drink before this test?
No special diet or fasting is required. However, if you’re also having blood drawn for other tests, let your provider know to coordinate timing for convenience.
  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