May-Thurner. this is classically described as compression of the left iliac vein underneath the left iliac artery. This can lead to narrowing of the deep venous system, leading to swelling of the left lower extremity with associated varicose veins. A CT scan would be helpful in determining if this is the case, and then stenting of the narrowed iliac vein would be recommended.
No short answer. Prevalent but underdiagnosed condition in which left common iliac vein deep in the pelvis is compressed by right common iliac artery. This is probably the reason left leg blood clots, potentially fatal, outnumber right leg clots. In addition to increasing clot risk, many patients have chronic left leg swelling for which nothing has been done There are right leg variants also.Treated by stenting.