Massive PE cause 50,000 deaths per year. Incidence probably rising with increasing surgical interventions, advances in intensive care, and longevity. A dark red clot forming a cast, equivalent to clotted blood in a test tube, due to stasis. Postmortem clots are ruled out by gross features, lacking cast form, wall and valve impressions. Occur in cardiac chambers, aorta, and iliacs.
Postmortem clots are cord like and elastic.
Sheets of red cells. Fibrin component not visible. Outer rims may show a few lines of Zahn. Classical lines of Zahn with even layers of ridges of platelets with adherent wbc's separated by valleys of red cells. This is proof of antemortem genesis because blood flow needed.