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CT Pulmonary Angiography for Suspected Pulmonary Embolism — With Intravenous Contrast

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

A CT scan uses intravenous contrast to examine the pulmonary arteries for blood clots associated with pulmonary embolism.

Quick summary

["This scan helps doctors find or rule out a blood clot in the arteries leading to the lungs."]

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

Key facts at a glance

LOINC
79077-4
Short code
CTA PA for PE W contr IV
Synonyms
CTA PA for PE W contr IV
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct-angio
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

What is this test?

CT pulmonary angiography is an imaging test that uses contrast material injected through a vein to show the blood vessels in and around the lungs. It is commonly used to look for pulmonary embolism, a blood clot that blocks blood flow through a lung artery.

Why might I need this test?

This test may be ordered for symptoms such as sudden shortness of breath, chest pain, coughing blood, or a rapid heartbeat. It may also be used when there is a concern for a blood clot after surgery, prolonged immobility, injury, or certain medical conditions.

How is the test performed?

You lie on a CT scanner table while images are taken. An intravenous line is used to inject contrast, and you may be asked to hold your breath briefly. The scan usually takes a short time, and you may be observed briefly afterward.

How do I prepare for the test?

Fasting is not usually required, but follow the instructions provided by the imaging center. Tell the care team about any previous contrast reaction, kidney disease, or possible pregnancy, because these factors may affect the procedure or contrast use.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CT pulmonary angiogram (CTPA)

Frequently asked questions

Is this the same as a CT scan of the chest?
It is a specialized CT examination focused on the pulmonary arteries. It uses intravenous contrast to make blood clots and the vessels supplying the lungs easier to see.
Will I need an IV line?
Yes. Intravenous contrast is usually injected through a small IV line in your arm or hand before and during the scan.
What if I am allergic to contrast dye?
Tell the imaging team about any previous reaction before the test. The clinician can then assess the risk and choose an appropriate plan, which may include preventive medication or an alternative imaging test.
  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