Two cases of massive pulmonary embolism occurring during the first trimester of pregnancy were documented by pulmonary angiography. The reported incidence of pulmonary embolism during pregnancy is exceedingly low. When embolism does occur during pregnancy, it is usually reported to be massive, as it was in our patients. Autopsies in patients with lethal embolism frequently show evidence of prior embolism which, in most cases, had not been clinically suspected. Therefore, a greater suspicion of embolism during pregnancy and a more thorough evaluation of suspected cases is warranted. Pulmonary angiography and radioisotope lung scans have a high degree of diagnostic specificity and should be utilized when indicated. When embolism occurs during pregnancy, protection is mandatory for the duration of pregnancy and the early postpartum period.
Evans GL, Dalen JE, Dexter L. Pulmonary Embolism During Pregnancy. JAMA. 1968;206(2):320-326. doi:10.1001/jama.1968.03150020036007