Background: Pulmonary thromboembolism (PTE) is still an enigmatic disorder in many epidemiological and clinical features, remaining one of the most commonly misdiagnosed disorders. Objective: To describe the prevalence and pathological findings of PTE in a series of autopsies, to correlate these findings with underlying diseases, and to verify the frequency of PTE clinically suspected before death. Method: The reports on 5261 consecutive autopsies performed from 1979 to 2002 in a Brazilian tertiary referral medical school were reviewed for a retrospective study. From the medical records and autopsy reports of the patients found with macroscopically and/or microscopically documented PTE, were gathered data on demographics, underlying diseases, antemortem suspicion of PTE, and probable PTE site of origin. Results: The autopsy rate was 42.0% and PTE was found in 544 patients. In 225 cases, PTE was the main cause of death (fatal PTE). Infections (p=0.0003) were associated with nonfatal PTE and trauma (p=0.007) with fatal PTE. The rate of antemortem unsuspected PTE was 84.6% and 40.0% of these patients presented fatal PTE. Diseases of the circulatory system (p=0.0001), infections (p<0.0001), diseases of the digestive system (p=0.0001), neoplasia (p=0.024) and trauma (p=0.005) were associated with unsuspected PTE. The most frequent PTE site of origin was the lower limbs (48.9%). Probable PTE sites of origin such as right-sided cardiac chambers (p=0.012) and pelvic veins (p=0.015) were associated with fatal PTE. Conclusion: A large number of cases do not have antemortem suspicion of PTE. Special attention should be paid to the possibility of PTE in patients with diseases of the circulatory system, infections, diseases of the digestive system, neoplasia, and trauma.

Keywords: Autopsy. Epidemiology. Pulmonary Thromboembolism.