Acute pulmonary embolism triggered by the act of defecation. Pulmonary embolism associated with the act of defecation has not been previously well described. Recently, we reported our experience with four patients who presented to us over a 12-month period with syncope, near syncope, or sudden death following the act of defecation. In all four cases, acute pulmonary embolism was shown to be the etiology of the defecation-associated events. A retrospective chart review of all patients with the diagnosis of pulmonary embolism at our institution over a three-year period yielded five additional patients with the diagnosis of defecation-associated pulmonary embolism. These nine patients accounted for 6.8 percent of all patients with a discharge diagnosis of pulmonary embolism seen at our institution during the three-year study period. Six of the nine patients died from their defecation-associated pulmonary embolism. These six deaths accounted for 25 percent of all deaths from pulmonary embolism seen at our institution during the study period. Based on our experience, we suggest that the act of defecation may trigger the development of acute pulmonary embolism in some patients with deep vein thrombosis. 