CONDITIONS WE TREAT
Iliac Vein Compression Syndrome (May-Thurner)
When a vein deep in the pelvis is squeezed shut, blood struggles to leave the leg — usually the left. The result is one-sided swelling, heaviness, and aching that compression stockings and superficial-vein treatments never quite fix. It is common, often missed, and very treatable.
What it is
Iliac vein compression syndrome — also called May-Thurner syndrome or a nonthrombotic iliac vein lesion — happens when the main vein draining the left leg is pinched between the artery crossing over it and the spine behind it. Years of that pressure irritate and scar the vein from the inside, narrowing it and blocking outflow. Blood backs up in the leg, and in some people a clot (DVT) forms on top of the narrowing.
What you might notice
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Swelling of one leg — usually the left — worse by the end of the day
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Heaviness, aching, or a bursting feeling with standing or walking
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Leg cramping when walking that eases with rest and elevation (venous claudication)
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Varicose veins, especially ones that return after treatment
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Skin discoloration or hardening near the ankle; in advanced cases, a venous ulcer
When it turns urgent
A sudden, painful, swollen, red leg can mean a deep-vein clot (DVT) forming on the compression — seek care promptly. In women, long-standing pelvic-vein congestion can also cause chronic pelvic pain.
Why it matters
Two forms, and the plan differs by which one you have:
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Nonthrombotic (pure compression). Narrowing without a clot. Reopening it with a stent works very well, with good long-term results.
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Post-thrombotic. Compression complicated by a past DVT, which leaves scarring and webs inside the vein. Still treatable, with a more involved plan and a longer blood-thinner course.
Risk Factors
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Left-sided anatomy. The right iliac artery crosses over the left iliac vein in most people; the compression is anatomic before it is pathologic.
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Female sex, and the reproductive years. Most symptomatic patients are women between roughly 20 and 50.
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Pregnancy and the postpartum period; oral contraceptives or hormone therapy
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Prolonged immobility, recent surgery, or a long period of bed rest
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A prior DVT in that leg, or varicose veins that returned after treatment
None of these cause the compression. They determine whether an anatomic squeeze becomes a symptomatic vein.
Diagnostic Testing
Standard leg ultrasound often cannot see these veins — they sit above the groin, deep in the pelvis — which is a large part of why this diagnosis is missed. We build the picture in steps.
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Venous duplex ultrasound — excludes clot and superficial reflux, and looks for indirect signs of a proximal blockage →
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CT or MR venography — shows the compression and the vein anatomy directly
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Venography with intravascular ultrasound (IVUS) — the definitive test. A tiny ultrasound on the catheter tip measures the vein from the inside and reveals narrowing an outside picture underestimates. We confirm the blockage is genuinely significant here before recommending a stent.
Treatment Options
Medical & Conservative Therapy
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Graduated compression, once the arteries have been checked
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Leg elevation, walking, and weight management
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Anticoagulation when a clot is present or has been, with duration set by cause
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Watchful waiting when a narrowing is incidental and the leg is not symptomatic
Compression manages the symptom. It does not reopen the vein, which is why it so often disappoints in this condition.
Invasive Treatments
IVUS-guided iliac vein stenting reopens the compressed segment and restores outflow, most often as a same-day, office-based procedure. Deep venous stenting →
When compression is complicated by an acute clot, clot removal comes first and follows its own site of service. DVT & PE intervention →
Not every narrowing needs a stent. We treat when symptoms are significant and IVUS confirms the blockage is real.
Frequently asked questions
For referring providers — We welcome referrals for one-sided leg swelling, suspected May-Thurner, left iliofemoral DVT (especially in younger women), recurrent varicose veins, and venous ulcers not responding to conservative care. Refer: (918) 943-5303 · fax (855) 312-3594.
Refer urgently: a suddenly painful, swollen, red leg (to exclude DVT) · Routinely: chronic one-sided leg swelling or recurrent varicose veins for evaluation. Full referral guide →