Studies that evaluated transthoracic ultrasound in patients with suspected pulmonary embolism compared to the reference standard of computed tomography (CT), magnetic resonance imaging (MRI) or a multi-diagnostic approach were eligible for inclusion. Studies needed to report sufficient data to construct a 2x2 table of test performance. One study was excluded because of selection bias of the included patients, which the authors claimed meant it was not comparable with the other included studies. Reviews, case reports, letters and comments were excluded.
Four studies used CT and a multimodality approach when the CT was negative as the reference standard; one study used MRI angiography. Mean age, where reported, ranged from 62 to 69 years. Prevalence of pulmonary embolism ranged from 49% to 64%.
Two reviewers independently assessed studies for inclusion. Disagreements were resolved through consensus.