What it is
The deep veins — femoral, iliac, and the inferior vena cava — carry almost all the blood leaving the leg. Deep venous disease is obstruction of that outflow, and it has three main causes:
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Iliac vein compression (May-Thurner syndrome), where the artery crossing over the left iliac vein pins it against the spine. It is the most common form of deep venous disease we treat. Iliac vein compression in detail →
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Post-thrombotic scarring after a deep vein clot, which leaves webs and thickened walls inside the vein →
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Other deep-vein obstruction, including compression from a mass or from scar after surgery or radiation
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Swelling of one leg (often the left) that doesn’t fully resolve with elevation or stockings
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Leg heaviness, aching, or fullness that worsens through the day
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Cramping with walking that eases with rest and elevation — venous claudication
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Skin changes or a slow-healing venous ulcer; a history of DVT in that leg
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Varicose veins that return after treatment
A vein squeezed shut upstream raises leg pressure just as effectively as a leaking valve does — and it is the one that gets missed. Treating superficial reflux in a leg whose real problem is an obstructed iliac vein does not fix the leg.
Why it matters
Left alone, deep venous obstruction produces post-thrombotic syndrome: chronic swelling, heaviness, skin damage, and eventually an ulcer. It also predisposes the leg to another clot, because blood that cannot leave a vein tends to clot in it.
Risk Factors
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A prior DVT, especially an iliofemoral one — the dominant risk factor.
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Left-sided anatomy. The right iliac artery crosses 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; pregnancy and the postpartum period.
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Oral contraceptives or hormone therapy; prolonged immobility or recent surgery.
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Obesity; prior pelvic surgery, radiation, or a pelvic mass.
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Recurrent varicose veins after an adequate superficial treatment.
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
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IVUS-guided iliac vein stenting to restore outflow →
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IVC filter placement and retrieval when clot protection is needed and anticoagulation is not possible →
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Clot removal for an acute, extensive clot — this follows its own site of service →
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, post-thrombotic syndrome, 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, recurrent varicose veins, or post-thrombotic symptoms. Full referral guide →