Javabean,
When I had my initial procedure, it was found that my left iliac was indeed compressed. It wasn't completely shut but enough to create a large collateral that spanned from the left into the right iliac.
I had it stented a couple of months later. I must say I had no drastic improvements other than perhaps my feet hurt less, but that is completely subjective. My feet still get cold when I'm sitting.
Objectively, I can say that the collateral did not show up on my last venogram and that blood flow from my legs is now normal. My left iliac is no longer engorged and is closer in size to the right.
The compressed area is a little lighter than the rest and the collateral begins just below it.
I believe that flow out of the right leg may may been hampered as a result of colliding with flow from the left. Who really knows...?
It has been talked about here that a compressed iliac may contribute to an azygous overload problem. If your azygous is fine, it should be able to accomadate any increased load caused by extra flow detoured to the ascending lumbar and ultimately the azygous.
Perhaps the iliac should be looked at if the azygous is found to have an issue? If any problems in the azygous are corrected, then overload should not be an issue so checking the iliac wouldn't be necessay, so that is why I think some doctors have stopped checking the left iliac and go in from the right side.
If your left leg is swelling up, that is a different matter!
Hope this sheds some light on the issue!