May-Thurner Syndrome, also known as iliac vein compression, occurs when the left iliac vein is compressed by an artery. It is a rare and underdiagnosed vascular disorder that occurs predominantly in individuals in the 20-40 age group and affects women twice as much as men.
The left iliac vein is the large vein that moves blood up the left leg and pelvis to the heart. A nearby artery can compress the iliac vein, restricting the flow of blood, and narrowing or scarring the vein. The artery may also compress the right iliac vein or both veins.