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Vq Scan (Lung Ventilation and Perfusion)

Medically reviewed by Last updated on Jan 5, 2023.


A VQ scan

is a test used to show the air flow and blood flow in your lungs. It is usually done if your provider thinks you have a pulmonary embolism (blood clot). A pulmonary embolism (PE) may be caused by a blood clot that travels from your leg to your lungs. A PE can become life-threatening. A VQ scan may show blood vessel blockages in your lungs. A VQ scan may be done before lung surgery to check how different parts of your lung are working.

How do I prepare for a VQ scan?

Your healthcare provider will talk to you about how to prepare for the test. He or she may tell you not to wear anything with metal hooks or snaps. The hooks and snaps may make it difficult for your provider to see any blockage. Tell your provider if you are pregnant or breastfeeding. Radiation exposure may harm your baby. You may need to pump and save your breast milk up to 2 days before your scan. This allows you to bottle feed your breast milk to your baby after the scan. You will need someone to drive you home if you get medicine to help you relax during the test.

What will happen during the VQ scan?

A VQ scan is usually done in 2 stages, one to check air flow and one to check blood flow. You will be awake for the scan. You will have to lie very still during the scan. Your provider may give you medicine to help you relax. A breathing mask is placed over your nose and mouth, during the air flow stage. You will breathe in a small amount of a radioactive substance as the scanner takes pictures. You will be asked to hold your breath for a few seconds at the beginning of each picture. For the blood flow stage, a small amount of radioactive liquid will be injected into a vein in your arm. The scanner will take pictures of the blood flow in your lungs.

What are the risks of a VQ scan?

There is a rare chance that the radioactive materials may cause an allergic reaction such as a rash. If you are breastfeeding, you may have you stop for up to 48 hours. Radioactive materials can be transferred to your baby through your breast milk. You will need to express your milk and pour it out for as long as directed. You will need to bottle feed your saved breast milk to your baby after your scan.

Call 911 for any of the following:

  • You feel lightheaded, short of breath, and have chest pain.
  • You cough up blood.
  • You suddenly have trouble breathing.

Contact your healthcare provider if:

You have questions or concerns about your condition or care.

Drink liquids:

Liquids help get radioactive substances out of your body. Ask your provider how much liquid to drink each day and which liquids are best.

Do not breastfeed after your scan:

You will need to express your milk and pour it out for as long as directed. You will need to bottle feed your saved breast milk to your baby after your scan. Ask your provider when you can start breastfeeding again.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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