Idiopathic just means you don't have any of the obvious big risk factors: surgery, broken leg, long period of inactivity (long trip, bed rest, etc.), overweight, sedentary lifestyle, birth control/hormone replacement therapy, etc. and you don't seem to have a family history.

I'm also "idiopathic." I've clotted three times and been run through all the tests several times and I'm negative for everything. I was told with my PEs that I might just have something that hasn't been discovered yet. They learn new things about clotting all the time, so maybe I'll know what I've "got" at some point ... but maybe not.

I read a study a few years ago (something my hema gave me) that said about 33% of clots fall into the category of "idiopathic." It might have been higher, actually, but I'm too lazy to pull it out of my file cabinet right now and look. Either way, rest assured that you're not quite as "rare" as your docs are making out.

As Toss says, ~30% of cases are idiopathic/unexplained/unprovoked, which means ~70% can be attributed to things like surgery, pregnancy, genetic factors, cancer ... Again from memory, these percentages were reversed 30 years ago, so progress happens. Being idiopathic isn't rare.

I think it's more unusual in someone who's young and otherwise healthy. I do recognize that I know people in this community and the DVT community who have had idiopathic clots so it doesn't seem that rare at all in that context.

My hematologist provided me with a very complex clinical rational for my idiopathic clots: "just really bad luck. "

I was told mine was idiopathic. I am 36, male, very fit and never had any health problems before. They didn't find any genetic disorders, cancer, etc. I felt great until I developed back spasms while out running one day. Then shortness of breath came on which got progressively worse over the next few days and I started coughing up blood. By the time I went to seek help I had extensive bilateral PE with large infarction of RLL. All my bloodwork showed was high levels of Homocyteine and elevated D-dimer of course.

I guess it seems better that I am not that "rare", that there are so many others that have experienced this without a real reason... I am not in the greatest shape I have been in, but consider myself somewhat athletic, and up until January had been working out a couple times a week. The only thing I can think of is that pre-PE, I was drinking a lot of coffee (and I mean a whole bunch) for years and not enough water. Also, at work, I had recently changed positions to one that keeps me in the office in my chair more. I didn't really notice it, but I might have at times been sitting there working on the computer several hours before getting up and moving around.. Perhaps this is the same as a long distance flight(?) Also, my chair was not the right size, and the edge of the chair would catch the back of my knees

There is no harm in trying to be a bit healthier, reducing the amount of coffee, staying hydrated, getting up from your office chair ... etc, but as the reason is unknown, don't beat yourself up too much. The idiopathic label could include genetic condition that hasn't been determined yet, among others.
We all want to know about why things occur, but if all the tests have been done, you might just have to accept the uncertainty.

I was diagnosed with Antiphospholipid syndrome or Lupus anticoagulant, which has also been explained to me is idiopathic. I guess it really doesn't matter what I call it but since I have had 4 episodes of PE's I am on Coumadin for life. At first I thought it really made a difference knowing my clotting disorder actually had a name, but it really doesn't. I still have to be on Coumadin, I still have the same worries as everyone else who is on Coumadin for life. So I tuck that information in a little box or corner in the back of my mind and don't really worry to much about it and try to get on with my life.
Hugs Ferr