A patient with sudden shortness of breath and leg swelling is most likely to require which initial diagnostic test?

In a case where a patient presents with sudden shortness of breath and leg swelling, the most appropriate initial diagnostic test is a bedside Doppler ultrasound of the right lower extremity. This test is particularly useful for assessing deep vein thrombosis (DVT), which can lead to pulmonary embolism (PE) and explain the patient's shortness of breath.

DVT is a common condition that can occur without clear symptoms, but when it does present, it typically manifests as unilateral leg swelling, which aligns with the symptoms described. Since a DVT can be a precursor to PE, this initial assessment can help rule out or confirm the presence of a thrombus, leading to appropriate management of the patient's condition.

Chest X-ray may be useful in evaluating many causes of shortness of breath, but it is less specific for detecting DVT or PE. Similarly, a computed tomography angiogram of the chest is more definitive for diagnosing PE but is generally not the first-line test for immediate evaluation, especially when considering the likelihood of a DVT. Echocardiography can be helpful for assessing cardiac function or other structural abnormalities but does not directly diagnose DVT.

In summary, a bedside Doppler ultrasound stands out as the most direct and relevant test for assessing the immediate