May-Thurner Syndrome: Clinical Presentation
May-Thurner syndrome (MTS) presents most commonly with left lower extremity swelling and pain due to compression of the left common iliac vein by the overlying right common iliac artery against the lumbar vertebrae. 1
Primary Clinical Manifestations
The hallmark symptoms of MTS include:
- Left leg swelling (edema) - the most frequent presenting complaint, typically isolated to the left lower extremity 2, 3, 4
- Left leg pain - often accompanies the swelling and may be described as aching or heaviness 2, 4, 5
- Varicosities - dilated superficial veins in the left leg due to chronic venous hypertension 2, 4
- Venous stasis changes - skin discoloration, induration, and chronic venous insufficiency signs 4
- Chronic venous stasis ulcers - in long-standing cases with persistent venous obstruction 2, 4
Acute Thrombotic Complications
MTS predisposes patients to left-sided iliofemoral deep vein thrombosis (DVT), which should be strongly suspected in young patients with unprovoked or recurrent left leg DVT. 1, 3
When acute DVT develops, patients present with:
- Sudden-onset left lower extremity edema and pain - acute worsening of baseline symptoms 5
- Limb-threatening circulatory compromise (phlegmasia cerulea dolens) - in severe cases requiring urgent intervention 1, 6
- Pulmonary embolism - a potentially life-threatening complication of iliofemoral DVT 2
Atypical Presentations
Importantly, MTS can present with right-sided symptoms despite left-sided venous compression. 7
Unusual manifestations include:
- Right-sided back and flank pain - documented in patients with >75% left iliac vein compression 7
- Right leg pain and swelling - paradoxically relieved by treating the left-sided venous obstruction 7
Age and Demographics
While MTS typically presents in the 2nd to 4th decades of life, it can occur at any age, including elderly patients with remote surgical history. 5
Chronic Manifestations
In untreated or chronic cases, patients develop:
- Venous claudication - leg pain with ambulation that improves with rest and elevation 5
- Post-thrombotic syndrome - chronic pain, swelling, and skin changes following DVT 8, 1
- Debilitating quality of life impairment - from persistent symptoms and functional limitations 5
Key Clinical Pitfall
A critical diagnostic error is attributing isolated left lower extremity swelling solely to superficial causes or assuming all leg swelling requires only duplex ultrasound evaluation. 4 Standard duplex ultrasound may not visualize the iliac vein compression, and CT venography or MR venography should be performed when MTS is suspected, particularly in young patients with left-sided symptoms or recurrent left leg DVT. 1, 4