van der Pol LM, Tromeur C, Bistervels IM, et al. Pregnancy-Adapted YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism. N Engl J Med. 2019 Mar 21;380(12):1139-1149. doi: 10.1056/NEJMoa1813865. (Original study)

BACKGROUND: Pulmonary embolism is one of the leading causes of maternal death in the Western world. Because of the low specificity and sensitivity of the d-dimer test, all pregnant women with suspected pulmonary embolism undergo computed tomographic (CT) pulmonary angiography or ventilation-perfusion scanning, both of which involve radiation exposure to the mother and fetus. Whether a pregnancy-adapted algorithm could be used to safely avoid diagnostic imaging in pregnant women with suspected pulmonary embolism is unknown.

METHODS: In a prospective study involving pregnant women with suspected pulmonary embolism, we assessed three 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. Pulmonary embolism was ruled out if none of the three criteria were met and the d-dimer level was less than 1000 ng per milliliter or if one or more of the three criteria were met and the d-dimer level was less than 500 ng per milliliter. Adaptation of the YEARS algorithm for pregnant women involved compression ultrasonography for women with symptoms of deep-vein thrombosis; if the results were positive (i.e., a clot was present), CT pulmonary angiography was not performed. All patients in whom pulmonary embolism had not been ruled out underwent CT pulmonary angiography. The primary outcome was the incidence of venous thromboembolism 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.

RESULTS: 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 [CI], 0.04 to 1.2); no patient had pulmonary embolism. CT pulmonary angiography was not indicated, and thus was avoided, in 195 patients (39%; 95% CI, 35 to 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.

CONCLUSIONS: Pulmonary embolism was safely ruled out by the pregnancy-adapted YEARS diagnostic algorithm across all trimesters of pregnancy. CT pulmonary angiography was avoided in 32 to 65% of patients. (Funded by Leiden University Medical Center and 17 other participating hospitals; Artemis Netherlands Trial Register number, NL5726.).

Discipline Area Score
Hemostasis and Thrombosis 6 / 7
Emergency Medicine 6 / 7
Hospital Doctor/Hospitalists 6 / 7
Internal Medicine 6 / 7
Obstetrics 6 / 7
Comments from MORE raters

Emergency Medicine rater

These patients would most likely be referred from the emergency department, so may not be as important to emergency physicians as those caring for this population.

Emergency Medicine rater

Important contribution as pregnancy-related literature is wanting. Given that the problem is likely one of over-testing, these findings are of value and warrant incorporation into clinical guidance.

Emergency Medicine rater

This is an excellent study of a difficult clinical problem with a result that is directly applicable to patients seen in the ED.

Emergency Medicine rater

Although the study is not a randomized trial and there are some protocol violations, this patient group is usually very challenging for emergency room physicians. The YEARS protocol clearly showed that we can avoid radiation load during pregnancy, especially in the first trimester, and it can be easily done in our departments.

Hospital Doctor/Hospitalists rater

Reducing unnecessary radiographic testing is a worthy goal, especially in pregnancy. The YEARS algorithm is straightforward to apply, but is not in common practice in my area. It is unclear to me how this compares with other similar evaluation tools. It is also unclear based on the presented data what the relative contribution of YEARS is over D-dimer scores alone.

Internal Medicine rater

Very useful to eliminate CTA in pregnant women.

Internal Medicine rater

This is one more useful tool to assess PE in pregnancy. It's good that clinical indicators are also being given due consideration.
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