Evaluation of the nonpregnant adult with low probability of pulmonary embolism

PE: pulmonary embolism; DVT: deep vein thrombosis; CT: computed tomography; PERC: pulmonary embolism rule-out criteria.
* We prefer the Wells criteria to determine the pretest probability of PE, although the modified Geneva score or clinical gestalt is also appropriate. Refer to UpToDate text for details.
¶ PERC is best used in the emergency department in patients with a low clinical pretest probability of PE and is not suitable for other clinical settings or in those with an intermediate or high pretest probability of PE. Some experts choose not to use PERC and proceed directly to sensitive D-Dimer testing.
Δ Feasibility requires adequate scanner technology. Also the patient must be able to lie flat, to cooperate with exam breath-holding instructions, have a body habitus that can fit into scanner, and no contraindications for iodinated contrast.
◊ Repeat CT pulmonary angiography for more definitive results may be worthwhile if the factor causing poor image quality can be mitigated (eg, patient more capable of cooperating with positioning and breath-holding instructions). Repeat imaging is unlikely to prove useful if exam was nondiagnostic due to factors such as scanner technology, body habitus, or indwelling metallic foreign bodies.
§ Feasibility requires a chest radiograph demonstrating clear lungs and a patient able to lie still for >30 minutes.
¥ Further testing first involves revisiting the feasibility of CT pulmonary angiography. If CT pulmonary angiography is still not feasible then lower extremity compression ultrasonography with Doppler is appropriate.