Pregnancy-adapted YEARS algorithm for diagnosis of suspected pulmonary embolism

Acute pulmonary embolism is one of the leading causes of maternal death, with the overall incidence reported to be 1.72 cases per 1000 deliveries, accounting for approximately 1 death in every 100,000 deliveries. Since the D-dimer test has low specificity and sensitivity, it is common for pregnant women with suspected pulmonary embolism to undergo computed tomography (CT) pulmonary angiography or ventilation-perfusion (V/Q) scanning, both of which involve radiation exposure to the mother and fetus. It is unknown whether a pregnancy-adapted clinical screening algorithm could be used to safely avoid diagnostic imaging in a subset of pregnant women with suspected pulmonary embolism. The researchers performed a multicenter, international, prospective study of pregnant women with suspected pulmonary embolism. They assessed 3 criteria from the YEARS algorithm (clinical signs of deep vein thrombosis, hemoptysis, and pulmonary embolism as the most likely diagnosis) and measured the D-dimer level as components of the screening algorithm. Pulmonary embolism was ruled out if none of the 3 criteria were met and the D-dimer level was less than 1000 ng/mL, or if 1 or more of the 3 criteria were met and the D-dimer level was less than 500 ng/mL. Adaptation of the YEARS algorithm for pregnant women involved compression ultrasonography for women with symptoms of deep vein thrombosis; if the results were positive (ie, a clot was present), CT pulmonary angiography was not performed. All patients in whom pulmonary embolism had not been ruled out by screening criteria underwent CT pulmonary angiography. The primary outcome was the incidence of venous thromboembolism (VTE) at 3 months. The secondary outcome was the proportion of patients in whom CT pulmonary angiography was not indicated to safely rule out pulmonary embolism. A total of 510 women were screened, of whom 12 (2.4%) were excluded. Pulmonary embolism was diagnosed in 20 patients (4.0%) at baseline. During follow-up, popliteal deep vein thrombosis was diagnosed in 1 patient (0.21%; 95% confidence interval, 0.0%–1.2%); no patient had pulmonary embolism. CT pulmonary angiography was not indicated, and thus was avoided, in 195 patients (39%; 95% confidence interval, 35%–44%). The efficiency of the algorithm was highest during the first trimester of pregnancy and lowest during the third trimester; CT pulmonary angiography was avoided in 65% of patients who began the study in the first trimester and in 32% who began the study in the third trimester. The researchers concluded that the pregnancy-adapted YEARS diagnostic algorithm safely ruled out acute pulmonary embolism in pregnant patients who were referred for suspected pulmonary embolism. Using this approach, they found that the main advantage was that CT pulmonary angiography was averted in 32% to 65% of the patients, depending on the trimester of presentation, without compromising safety.

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