Family History

Is a chest CT scan or a VQ scan contraindicated if I have a family history of breast cancer?
Yes. Having a family history of breast cancer does not mean you can’t get a chest CT scan or a VQ scan. These tests are still considered safe and recommended to look for a blood clot in your lungs.

Could a chest CT scan or a VQ scan give me breast cancer?
No. Chest CT and VQ scans performed during pregnancy do not increase the risk of early-onset breast cancer [1].

Breastfeeding

Can a chest CT scan affect my breastfeeding?
No, the CT scan does not affect breastfeeding.


If I am currently breastfeeding, should I stop breastfeeding after I get a chest CT scan?
No. It is not necessary to stop breastfeeding after a CT scan [2].


If I am currently breastfeeding, should I stop breastfeeding after I get a VQ scan?
Maybe. Some types of VQ scan use dye that stays in your body for a bit. In some cases, you may need to pump and store or throw away breastmilk for 12 to 24 hours [3,4]. Your doctor will be able to give you more information about this.

Timing and Experience

How much time do I have to make a decision about getting a scan of my chest to diagnose or rule out a pulmonary embolism?
The decision must be made as soon as possible so that the test can be obtained quickly.


What are the imaging options to diagnose or rule out a pulmonary embolism?
There are two common tests: a chest CT scan and a VQ scan. Both tests are accurate and considered safe in pregnancy. The choice of one test over another will depend by what machine is available right now and whether your medical team needs to look for something else in your lungs. You can discuss this further with your doctor.


Is a chest CT scan or a VQ scan painful?
No. A chest CT scan or a VQ scan is not expected to be painful. However, these tests require the insertion of an intravenous (IV) line, which includes a small needle poke.

In addition, the intravenous dye given for a chest CT scan may cause a warm sensation spreading through the body for a few seconds during and after the injection. The dye may also cause nausea that lasts for a short time during and after the injection. This is normal and will go away on its own.

Evidence

Are these imaging techniques recommended by any organization?
Yes. Chest CT and VQ scans are recommended to rule out PE by many organizations, including the Society for Obstetricians and Gynaecologists of Canada [5], the American Society of Hematology [6], and the American College of Obstetricians and Gynecologists [7].

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How does a chest CT scan or VQ scan compare to other sources of radiation?
The dose of radiation from one chest CT scan or one VQ scan is much lower than the background exposure to radiation in normal, everyday life over a year [8].
Depending on the situation, it can also be similar to a round trip flight to Europe [8].

References

​1. Burton KR, Park AL, Fralick M, Ray JG. Risk of early-onset breast cancer among women exposed to thoracic computed tomography in pregnancy or early postpartum. J Thromb Haemost. May 2018;16(5):876-885. doi:10.1111/jth.13980
2. American College of Radiology. ACR manual on contrast media. Accessed May 18, 2025. https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Contrast-Manual
3. Drugs and Lactation Database (LactMed). National Library of Medicine (US); 2006.
4. Mitchell KB, Fleming MM, Anderson PO, et al. ABM Clinical Protocol #31: Radiology and Nuclear Medicine Studies in Lactating Women. Breastfeeding Medicine. 2019/06/01 2019;14(5):290-294. doi:10.1089/bfm.2019.29128.kbm
5. Chan WS, Rey E, Kent NE, et al. Venous thromboembolism and antithrombotic therapy in pregnancy. J Obstet Gynaecol Can. Jun 2014;36(6):527-53.
6. Bates SM, Rajasekhar A, Middeldorp S, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: venous thromboembolism in the context of pregnancy. Blood Adv. Nov 27 2018;2(22):3317-3359. doi:10.1182/bloodadvances.2018024802
7. ACOG Practice Bulletin No. 196: Thromboembolism in Pregnancy. Obstetrics and gynecology. Jul 2018;132(1):e1-e17. doi:10.1097/aog.0000000000002706
8. Lowe S. Diagnostic imaging in pregnancy: Making informed decisions. Obstetric medicine. 2019/09/01/ 2019;12(3):116-122. doi:10.1177/1753495X19838658