There is acute thrombus within the common iliacs, external and internal iliac veins, and common femoral veins bilaterally. Above the confluence of the common iliac veins, the inferior vena cava is inapparent. Multiple collateral vessels are present around the aorta and the azygous and hemiazygous veins are prominent. The portal venous axis is patent. Over 600,000 cases of pulmonary embolism occur each year in the United States, with one-third of episodes leading to death.
Findings are nonspecific and often lead to a failure to diagnose.
The most common source for pulmonary emboli is deep venous thrombosis of the lower extremities. Other sites include the internal iliac veins, the inferior vena cava, upper extremities, mural thrombus within the right heart, renal veins and tumor emboli. CT may be used in patients who are at high risk for complications of arteriography. On CT, emboli appear as intraluminal filling defects. There may be evidence of infarction, such as wedge-shaped areas of parenchymal consolidation adjacent to a pleural surface.