Risks of CTPA During the 3rd Trimester of Pregnancy

Radiation Exposure Risks

Modern CTPA techniques during the third trimester of pregnancy pose minimal risks to both mother and fetus, with fetal radiation doses well below the threshold for complications and negligible lifetime cancer risk increase for the mother, according to the European Society of Cardiology 1, 2
Fetal radiation doses from properly performed CTPA are well below the threshold associated with fetal radiation complications, which is 50-100 mSv, as stated by the European Society of Cardiology 1, 2
The effect on maternal cancer risk with modern CTPA techniques is negligible, with a lifetime cancer risk reportedly increased by a factor of 1.0003-1.0007, according to the European Society of Cardiology 2
Modern CTPA imaging techniques expose the maternal breast to median doses as low as 3-4 mGy, as reported by the European Society of Cardiology 2

Inconclusive results can be more common in late pregnancy, with 43% of investigations being inconclusive, as stated by the European Society of Cardiology 2
CTPA protocols should be specifically adapted for pregnancy to account for physiological changes, as recommended by the American Thoracic Society 3
Optimization techniques for CTPA protocols in pregnancy include reducing anatomical coverage of the scan, using iterative reconstructive techniques, and reducing the contrast-monitoring component, as stated by the European Society of Cardiology 2

If chest X-ray is normal, perfusion lung scan may be considered as an alternative to CTPA, as suggested by the American College of Chest Physicians, but not exclusively from Praxis Medical Insights 4
D-dimer testing has limited utility in the third trimester as levels naturally increase during pregnancy, with only 4.2% of women with non-high pre-test probability having a negative D-dimer result, according to the European Society of Cardiology 1, 4

Relying on D-dimer testing in the third trimester is a pitfall, as levels naturally increase during pregnancy, and the solution is to use alternative diagnostic methods, as stated by the European Society of Cardiology 1
Repeated imaging due to non-diagnostic studies can be avoided by optimizing the first CTPA study with pregnancy-specific protocols, as recommended by the American Thoracic Society, but not exclusively from Praxis Medical Insights 3