Postductal Oxygen Saturation in Blood
This test measures the oxygen saturation level in blood taken from a blood vessel after it passes through the pulmonary artery, providing insight into how well oxygen is being delivered to the body’s tissues.
["Assesses oxygen efficiency in blood after the lungs have oxygenated it."]
Key facts at a glance
- LOINC
- 19955-4
- Short code
- OxyHgb % Bld Postductal
- Synonyms
- OxyHgb % Bld Postductal
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85018
- SNOMED
- 900000000000003004
- 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
Why Is This Test Done?
Your healthcare provider may order this test to evaluate lung function, detect potential breathing issues, or monitor conditions like congenital heart defects, respiratory disorders, or oxygen-related complications in newborns or critically ill patients.
Who Might Need This Test?
Commonly performed in newborns to check for heart or lung problems, or in patients with suspected oxygen imbalance due to conditions like pneumonia, asthma, or severe anemia.
What to Expect Before the Test
The test typically involves drawing a small sample of blood from a vein (often in the arm or heel of a newborn). You may feel a brief pinch, but it usually doesn’t cause significant discomfort. Recovery is immediate, and no special preparation is needed.
What Happens During the Test?
A healthcare professional will insert a small needle into a vein to collect a blood sample. The sample is then analyzed in real-time using specialized equipment to measure oxygen saturation levels.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low oxygen saturation postductal blood can indicate problems with lung function, blood flow, or oxygen transport. High levels may suggest conditions like polycythemia (increased red blood cells) or certain metabolic disorders. Results help guide treatment for breathing difficulties or other systemic issues.
Short name
Postductal Oxygen Saturation (O₂ Sat)
Frequently asked questions
What does a low oxygen saturation level mean?
How often is this test repeated?
Can diet or activity affect this test result?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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