We discriminate May-Thurner-syndrome (aka Cockett’s syndrome), which is May-Thurner-constellation with thrombosis of the left pelvic veins or the left leg, from its preliminary stage,from the May-Thurner-constellation, in which the symptoms described below occur before a thrombosis may develop.

Frequent symptoms of the May -Thurner-syndrome and May-Thurner-constellation:

1. pelvic pain (often on the left side)
2. radiating to the left thigh
3. left flank pain
4. swelling and heaviness of the left leg
5. tendency to develop thromboses and varices in the left leg

In May-Thurner-syndrome (named after two Swiss physicians who described the condition first) the blood from the left side of the pelvis cannot pass easily across the sacral bone to enter the inferior vene cava. The left common iliac vein is compresseed by the sacral bone form behind and by the right common iliac artery from above.

left: the sacral bone and its promontory (Promontorium) compress the left common iliac vein (VIC) from behind – color Doppler ultrasound image right: MR-Angiography shows flattening and signal extinction of the left common iliac vein on the promontory

Due to the increased pressure inside the left common iliac vein the blood is circumvented to bypass the promontory. It runs backwards into the left internal iliac vein across the midline organs of the pelvis. These are the uterus (prostate), the ovaries, the urinary bladder, the vagina, the urethra and the rectum, the external genitals (greater labia in women and the root of the penis in men).

After crossing these organs in a manner and extent that varies greatly among individuals, the blood from the left part of the pelvis and the left leg enters the right internal iliac vein to be transported with the blood from the right leg into the inferior vena cava. If the additional volume from the left side is large it may hamper the drainage of the right leg. Then, not only swelling of the left leg but also of the right one can be observed. If the passage across these midline organs is difficult due to the usually smaller veins of these organs, pain and dysfunction of these organs may occur. These are rectal bleeding and constipation, painful and frequent micturation, painful sexual intercourse, painful menstruation, prominent and painful veins in the genitals (mainly of the left labia), varices of the left leg, pain of the left ovary and in the center of the pelvis due to uterus varices.

This is then called midline (congestion) syndrome.

A more detailed desription of vascular compression syndromes can be downloaded here.

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