Because this pregnant patient with suspected PE has no known underlying lung disease and a normal chest radiograph, perfusion lung scintigraphy (performed without a ventilation study and often at half-dose of technetium 99m) is an appropriate initial test that has a low percentage of nondiagnostic scans.3 Although the fetus is exposed to slightly higher levels of radiation
with pulmonary scintigraphy as compared with CTPA (0.11 mGy versus 0.01 mGy), this dose remains well below the established threshold of 50 mGy
to avoid known fetal malformations, and this dose may be cut in half by requesting a half-dose of perfusion agent. Duplex ultrasonography is effective and safe in diagnosing DVT. It is most sensitive if leg symptoms are present, and it is less sensitive in pregnant patients, who often develop DVT in pelvic veins, which cannot be imaged by ultrasonography. Echocardiography is an effective tool to assess risk for shock or death in patients with PE, but it is insensitive as a diagnostic tool (sensitivity, 52%).4 CTPA is an acceptable test in pregnancy, but this modality exposes the mother to higher levels of radiation and may pose an unacceptably high risk of malignancy to proliferating maternal breast tissue. Because of this, CTPA is recommended only in cases when the mother has an underlying lung disease (eg, asthma, COPD) or when frontal chest radiography is abnormal. Invasive pulmonary angiography is not recommended as an initial diagnostic test because it has the highest risk of complications; however, it may be useful when less invasive tests are nondiagnostic and clinical suspicion for PE remains high.
- Perfusion lung scintigraphy.
3. Scarsbrook AF, Bradley KM, Gleeson FV. Perfusion scintigraphy: diagnostic utility in pregnant women with suspected pulmonary embolic disease. Eur Radiol 2007 Mar 7; [Epub ahead of print].
4. Bova C, Greco F, Misuraca G, et al. Diagnostic utility of echocardiography in patients with suspected pulmonary embolism. Am J Emerg Med 2003;21:180-3.
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