Objective: To determine whether a pregnancy-adapted clinical and D-dimer-based algorithm, termed the "YEARS algorithm," can reduce the need for radiological imaging, including lung scintigraphy in pregnant women with suspected pulmonary embolism (PE).
Patients and methods: This retrospective study included all pregnant women with suspected PE between January 2014 and September 2019 who have undergone D-dimer testing and radiological imaging (computed tomography pulmonary angiography or lung perfusion scans) at presentation. Three criteria from the YEARS algorithm were assessed: clinical signs of deep vein thrombosis, haemoptysis, and whether PE was clinically considered as the most likely diagnosis. Patients who did not have to undergo imaging per the YEARS algorithm were defined as those with no YEARS criteria and a D-dimer of <1μg/mL (group 1) and those with 1-3 YEARS criteria and a D-dimer of <0.5μg/mL (group 2). Patients who had to undergo imaging were those with no YEARS criteria and a D-dimer ≥1μg/mL (group 3) and those with 1-3 YEARS criteria and a D-dimer ≥0.5μg/mL (group 4). Women with symptoms of deep-vein thrombosis had to undergo Doppler ultrasound: If positive, they were anticoagulated and excluded from this analysis, and if negative, they were evaluated further for the need of imaging based on other YEARS criteria and D-dimer level.
Results: Of 117 pregnant women with suspected PE analyzed according to the YEARS algorithm five had confirmed deep-vein thrombosis by Doppler ultrasound, were anticoagulated and excluded from the analysis. Of the remaining 112 women (mean age; 30.4±5.7 years), 50 underwent computed tomography pulmonary angiography (CTPA), 54 lung perfusion or ventilation-perfusion (V/Q) scan and eight both; PE was diagnosed in 7 (6.25%), two by CTPA, two by lung perfusion or V/Q scan and three by both. Thirty-three of the 112 women (29.5%) were in groups 1+2 and could, therefore, have avoided CTPA or lung perfusion scans per the YEARS algorithm. None of those 33 women had PE by CTPA or lung perfusion scans vs. 7/79 patients (8.9%) who required CTPA or lung perfusion scans per the YEARS algorithm.
Conclusion: The pregnancy-adapted YEARS algorithm can safely rule out PE in about one-third of pregnant women with suspected PE without the need for radiological imaging.