*-Less than 2 percent PE with moderately sensitive d-dimer test (85 to 98 percent) and less than 1 percent PE with highly sensitive d-dimer test (greater than 98 percent).

†-Approximately 1 percent with PE.

‡-Positive helical CT indicates intraluminal filling defects in segmental or larger pulmonary arteries.

§ -Consider serial bilateral ultrasound examination of proximal leg veins in patients with negative results.

|| -Preferred in the following instances: if a subsegmental intraluminal filling defect is seen on initial helical CT scan; if there is a high-probability V/Q scan in a low-risk patient; if serial testing is not feasible; or if symptoms are severe and there is a need to exclude PE from the differential diagnosis.