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Pulse Oximetry (Oxygen Saturation via Pulse-Contingent Electrochemical Sensor in Whole Blood)

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

This test measures how much oxygen is attached to your red blood cells while you're resting or during activity. It’s a quick, painless check often done on your finger or earlobe.

Quick summary

["Assesses oxygen levels in your blood to monitor breathing health or detect potential issues like low oxygen or circulation problems."]

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

Key facts at a glance

LOINC
59412-7
Short code
SaO2 p Exc % BldA PulseOx
Synonyms
SaO2 p Exc % BldA PulseOx
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
pulse-oximetry
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 It Works

A small sensor attached to your finger or earlobe sends light through your blood vessels. The sensor detects the light absorbed by oxygenated and deoxygenated hemoglobin, giving your oxygen saturation percentage.

What to Expect

You’ll likely feel a small probe on your finger or earlobe. The test takes just a few minutes and doesn’t require fasting or special preparation.

Common Uses

Doctors may use this test to check for breathing problems, heart conditions, or to monitor oxygen levels during surgery, sleep studies, or after injuries.

Why It Matters

Oxygen saturation helps identify if you’re getting enough oxygen, which is critical for energy, brain function, and overall health. Low levels can signal serious conditions like anemia, lung disease, or heart problems.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Pulse Oximetry

Frequently asked questions

What causes false results?
Cold hands, nail polish, motion, or poor circulation can sometimes affect accuracy. If your sensor isn’t working well, your doctor may ask for a blood gas test for more detailed results.
Can I eat or drink before this test?
No special preparation is needed. You can eat, drink, or take medications normally before this test.
How often is this test done?
This test is often quick and routine, like checking your blood pressure. It may be done more frequently if you have ongoing health conditions like heart disease or lung problems.
  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