From the Guidelines
CT pulmonary embolism (PE) studies are generally considered safe during pregnancy when medically necessary, though they do expose the fetus to a small amount of radiation. The radiation dose from a CT PE study is typically below the threshold considered harmful to the developing fetus (usually less than 10 mGy) 1. When a pregnant woman has symptoms suggesting a pulmonary embolism, the risk of not diagnosing and treating this potentially life-threatening condition outweighs the minimal radiation risk to the fetus.
Key Considerations
- Physicians may first consider alternative diagnostic approaches without radiation, such as leg ultrasound if deep vein thrombosis is suspected, or may opt for ventilation-perfusion (V/Q) scanning which delivers less radiation to the fetus in some cases 1.
- However, CT PE often provides more definitive results and may be necessary for proper diagnosis.
- During the procedure, the abdomen and pelvis are typically shielded to further reduce fetal radiation exposure.
- The contrast agent used in CT scans crosses the placenta but has not been shown to cause harm to the developing fetus 1.
Diagnostic Approach
- A chest X-ray (CXR) is recommended as the first radiation-associated procedure in the imaging work-up for pregnant women with suspected PE 1.
- If the CXR is abnormal, CT pulmonary angiography (CTPA) is recommended as the first-line option to rule out suspected PE in pregnant women 1.
Clinical Decision-Making
- The decision to perform a CT PE scan during pregnancy should be made after careful consideration of the clinical situation and discussion between the patient and healthcare provider about the risks and benefits 1.
- Formal diagnostic assessment with validated methods is recommended if PE is suspected during pregnancy or in the post-partum period 1.
From the Research
Safety of CT PE in Pregnancy
- The safety of CT pulmonary embolism (CT PE) in pregnancy is a topic of interest due to the potential risks of radiation exposure to the fetus and mother 2, 3.
- Studies have shown that CT PE can be safely used in pregnant women with suspected pulmonary embolism, with a low failure rate and no significant adverse effects on the fetus or mother 2, 3.
- However, it is recommended to use CT PE only when necessary and to minimize radiation exposure by using low-dose protocols and alternative imaging tests, such as ventilation-perfusion scans, when possible 2, 3.
Diagnostic Strategies for Pulmonary Embolism in Pregnancy
- Clinical prediction rules and D-dimer testing can be used to reduce the need for diagnostic imaging in pregnant women with suspected pulmonary embolism 2, 3, 4.
- A diagnostic strategy based on assessment of clinical probability, D-dimer measurement, and imaging tests, such as CT PE or ventilation-perfusion scans, can safely rule out pulmonary embolism in pregnant women 2, 3.
- The use of low-molecular-weight heparin as an anticoagulant is recommended for both prophylaxis and treatment of pulmonary embolism in pregnancy 4.
Limitations and Controversies
- There is limited high-quality data available to guide the management of pulmonary embolism in pregnancy, and existing clinical guidelines provide weak recommendations on selecting the appropriate investigations for suspected pulmonary embolism in pregnancy 5, 6.
- Further research is needed to improve the diagnosis and management of pulmonary embolism in pregnancy, including the development of specific clinical prediction rules and D-dimer cutoffs adapted to pregnant women 2, 6.