DIAGNOSIS OF PULMONARY EMBOLISM: A CONTINUING DILEMMA. ELGAZZAR, A.H. MD, FCAP and AL ENIZI, E. MD, KBNM Department of Nuclear Medicine, Kuwait University.

Abstract

Basic considerations: 1 The vast majority of pulmonary emboli are thromboemboli originating from deep veins. Fat, air, or tumor emboli are rare [1]. Fat emboli are reported with long bone fractures and liposuction while air emboli occur with cardiac and neurosurgeries. Renal cell carcinoma with invasion reaching inferior vena cava is a clinical setting that may lead to tumor emboli. Data indicate that 90% of pulmonary thromboemboli originate from the lower extremities and pelvis. The remainder come from thrombi that occur in the right side of the heart or in bronchial or cervical veins. Embolization and symptomatology are proportional to how proximal is the vein that contains the thrombus. The vast majority of pulmonary thromboemboli originating from thrombi of the lower extremities come more frequently from the thigh and pelvis (75%) than from smaller veins of the calf and feet [2,3]. The risk of pulmonary embolus is also directly related to the presence of a residual clot at the site of a venous thrombus [4]. One of three events can happen during the natural history of venous thrombi. First, the red thrombus grows explosively and obstructs the vein