Hi there - I'm also a 43 y.o. female with sudden mysterious, multiple PE's in both lungs. just got out of the hospital, still doing my Fragmin shots and coumadin, etc. We're putting my cause down to the birth control and being overweight, but my doctor in the hospital, who used to be the clinic director at a coagulation clinic and has a special interest in this stuff says that once I'm off the coumadin therapy for 2 weeks they can run a 'hypercoaguability panel' - that includes a Factor II and other tests, to determine if there are genetic factors - if so they would likely recommend lifetime coumadin as a reasonable preventitive since the risk of more clots would be higher.
Another interesting note - he asked if I or any other female in my family has had problems with spontaneous miscarriages (my mom did) - apparently, even though this isn't directly an embolism problem, it indicates a higher potential for genetic predisposition to DVT/PE, etc.