 [ Symptoms ] bronchitis 10 days cefdinar 300mg   no help one day medrol pak no help nowvibramycin 100mg what should i expect [ Disease ] i am so very sorry to hear about the loss of your sister and her baby my condolences to you and your entire family i admire your willingness to write a paper on the very topic that took your sister is life i think that takes a lot of strength and courage to answer your question a pulmonary embolism is caused when all or part of a blood clot breaks loose in a vein travels to the lungs and blocks a major artery there usually a small part of a much larger clot or  thrombus  breaks off and causes the embolism we know these large clots usually occur in leg veins so the medical examiner probably opened up the femoral vein and saw the remaining portion of the large clot still residing within the vein that is how he or she knew where the clot came from in a living person it can sometimes be impossible to determine where an embolism causing clot came from many people with blood clots in their legs have no symptoms i hope you find this answer useful good luck with your paper