Diagnosis of Pulmonary Embolus

In patients with suspected pulmonary embolism, posterior/anterior and lateral chest X-rays are recommended as an initial imaging examination because they may reveal an alternate diagnosis and obviate the need for further imaging. If the chest X-ray is negative and the patient has a D-dimer level over an age-adjusted threshold, CT pulmonary angiography (CTPA) is the examination of choice. Ventilation/perfusion scintigraphy is recommended only for patients who are allergic to iodinated contrast media or have poor kidney function. It should also be considered in young women because the breast radiation dose is lower than CTPA. In pregnant patients with symptoms of deep vein thrombosis, compression ultrasound may yield sufficient information to initiate treatment and avoid radiation exposure. If pulmonary embolism imaging is required in pregnancy, CTPA delivers lower radiation exposure to the fetus and is the imaging modality of choice.