Skip to content

Pulse Oximetry (Oxygen Saturation in Whole Blood)

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

This test measures how much oxygen is bound to your red blood cells while you're at rest. It’s a quick, painless way to check your oxygen levels in the blood.

Quick summary

["A pulse oximeter helps monitor oxygen levels safely and easily during routine blood tests or at home."]

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

Key facts at a glance

LOINC
59416-8
Short code
SaO2 pre Tx % BldA PulseOx
Synonyms
SaO2 pre Tx % 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 is placed on your finger, toe, or ear to shine light through your blood vessels. The sensor detects the amount of oxygen attached to hemoglobin (the protein in red blood cells that carries oxygen). This is done without drawing blood, making it a non-invasive test.

What to Expect

You’ll likely be asked to sit still for a few minutes while the sensor stays in place. The test takes only a few seconds to complete, and you can usually resume normal activities immediately afterward.

Why It’s Done

Doctors may order pulse oximetry to check for low oxygen levels in people with breathing problems, heart conditions, or those recovering from surgery. It’s also used during sleep studies or in emergency situations to assess oxygenation quickly.

Common Conditions Monitored

This test helps identify issues like chronic obstructive pulmonary disease (COPD), sleep apnea, anemia, or severe infections that may affect oxygen levels. It’s also useful for monitoring patients with known heart or lung conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Pulse Ox

Frequently asked questions

What causes low oxygen levels (hypoxemia) in this test?
Low oxygen levels can occur due to breathing problems (e.g., asthma, pneumonia), heart issues (e.g., heart failure), or conditions that reduce blood flow (e.g., shock). It may also be affected by motion, cold temperatures, or certain medications.
How often should I get this test?
The frequency depends on your health condition. Some people may need it daily (e.g., during sleep studies or home monitoring), while others may only need it occasionally (e.g., before surgery or during routine check-ups). Always follow your healthcare provider’s instructions.
Does this test hurt?
No, this test is completely painless. The sensor is gentle and doesn’t require needles or blood draws. If you’re anxious, let your provider know—they may offer distractions or reassurance.
  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