One of the most frequent questions that I get regarding my DVT is about the cause. If it happens to be a medical professional doing the asking, they immediately run through a list of tests, usually related to finding a genetic abnormality. Unfortunately, all of these tests have now come back negative. Twice.

I am only able to share two bits of information in response to these questions. First, my DVT seven years ago damaged my veins, thereby making last year’s occurrence more likely. Second, DVTs are more likely to occur in the left leg because of the positioning of the veins. Yesterday, I came upon an interesting picture related to this point: Wikipedia’s featured picture of the day.

In this image, the person is facing you (anterior view). In other words, the person’s left leg is on the right side. Arteries are shown in red, and veins are in blue, as is typical.

Now, if you look closely at where the vessels branch into the legs (the iliac veins and arteries), you’ll notice that the artery runs over the vein as it enters the left leg (right side of the picture). However, the vein to the other leg runs unobstructed. The pressure of the artery is able to exert force on the vein running under it, potentially obstructing the smooth return of blood to the heart.

None of this actually explains why I would have developed the clot in the first place. But as my physician said, the cause doesn’t really matter any more. It’s happened twice, so now I’ll likely be treated for it for the rest of my life. I’ve heard of some new drugs recently approved by the FDA for similar conditions. They perform the same function (blood thinning) as my current medication (coumadin) without having to worry quite so much about hemorrhaging or constant INR monitoring. I see my specialist next week, so we’ll see what develops…