What is the presentation, diagnostic work‑up, and optimal management of May‑Thurner syndrome in a young woman (20‑50 years) with an isolated left‑leg deep‑venous thrombosis and no typical risk factors?

May-Thurner Syndrome in Young Women with Isolated Left-Leg DVT

Clinical Presentation

Young women (20–50 years) presenting with unprovoked left-sided iliofemoral DVT should immediately raise suspicion for May-Thurner syndrome, as anatomic compression of the left common iliac vein by the overlying right common iliac artery is significantly more prevalent in this population. 1

Key Clinical Features to Identify

• Unilateral left lower extremity pain and swelling without typical DVT risk factors (no recent surgery, immobilization, malignancy, or thrombophilia) 2, 3
• Recurrent left-leg DVT despite adequate anticoagulation suggests underlying mechanical compression 2, 3
• Phlegmasia cerulea dolens (severe limb-threatening venous congestion with cyanosis) represents the most severe presentation requiring urgent intervention 4

Diagnostic Work-Up

Initial Imaging

• Duplex ultrasound is the first-line test to confirm DVT, though it typically cannot visualize the iliac vein compression itself 4
• CT venography or MR venography must be performed when May-Thurner syndrome is suspected to directly visualize the left common iliac vein compression between the right common iliac artery and lumbar vertebrae 4, 5

Confirmatory Assessment

• Intravascular ultrasound (IVUS) during venography provides definitive assessment of the degree of venous stenosis and guides stent sizing 5

Optimal Management Strategy

Immediate Anticoagulation

Start therapeutic anticoagulation immediately upon DVT diagnosis with low-molecular-weight heparin (LMWH) or a direct oral anticoagulant (DOAC). 4, 6

• LMWH is superior to unfractionated heparin for reducing mortality and major bleeding risk 4
• DOACs (apixaban, rivaroxaban, edoxaban, dabigatran) are strongly preferred over warfarin 6

Definitive Endovascular Treatment

Combined catheter-directed thrombolysis (CDT) or pharmacomechanical thrombectomy (PMT) followed by iliac vein stenting plus continued anticoagulation is the preferred treatment; anticoagulation alone leads to significantly higher recurrent VTE rates. 1, 7

Treatment Algorithm for Acute DVT (< 14 days)

1. Perform CDT or PMT first to remove thrombus burden before stenting (Class IIa recommendation) 1, 7

   • Pharmacomechanical thrombectomy reduces thrombolytic drug dose by 40–50% and shortens infusion time compared to CDT alone 7

2. Follow with balloon angioplasty and self-expanding iliac vein stent placement to address the anatomic compression 1, 7

   • Angioplasty alone typically fails due to elastic recoil of the compressed vein 7
   • Confine stents to the iliac vein whenever feasible for optimal patency 7
   • If the lesion extends into the common femoral vein, caudal stent extension is reasonable (90% vs 84% patency) 7

3. For phlegmasia cerulea dolens, CDT or PMT is a Class I recommendation; surgical thrombectomy is reserved for contraindications to thrombolysis or imminent gangrene 4

Treatment for Chronic or Non-Thrombotic Presentation

• Stent placement without prior thrombolysis achieves 83–98% anatomic success for chronically occluded iliac veins and significantly improves quality of life 7
• This approach enables venous ulcer healing in approximately 56% of patients 7

Post-Stenting Anticoagulation

Continue therapeutic anticoagulation indefinitely after stenting because the anatomic compression represents a chronic, persistent risk factor for recurrent VTE. 6, 1

Anticoagulation Regimen

• Minimum 3 months of therapeutic-dose DOAC (apixaban, rivaroxaban, edoxaban, or dabigatran) 6
• After 3 months, continue indefinitely with either:
  • Standard therapeutic-dose DOAC, or
  • Reduced-dose DOAC (rivaroxaban 10 mg daily or apixaban 2.5 mg twice daily) based on bleeding risk 6
• If warfarin is used, target INR 2.5 (range 2.0–3.0) 6

Adjunctive Antiplatelet Therapy

• Add antiplatelet therapy to anticoagulation in high-risk patients (poor inflow vein quality or suboptimal stent result) after individualized bleeding-risk assessment 7
• One case report demonstrated successful prevention of recurrent thrombosis using dual antiplatelet therapy (aspirin plus clopidogrel) combined with enoxaparin in a patient with refractory thrombosis 2

Compression Therapy

Prescribe 30–40 mm Hg knee-high elastic compression stockings for at least 2 years to reduce post-thrombotic syndrome risk 7, 4

Expected Outcomes

• At 3 years post-stenting, 79% of patients maintain pain reduction and 66% maintain swelling reduction, demonstrating durable symptom relief 7
• Primary stent patency with anticoagulation approaches 60–100% at one year 6
• Initial symptom improvement occurs in 95% of patients, with sustained benefits in the majority 7

Critical Pitfalls to Avoid

Do Not Rely on Anticoagulation Alone

Anticoagulation without stenting is inadequate because the persistent anatomic compression predisposes to recurrent VTE; recurrent thrombosis occurs significantly more frequently with anticoagulation alone compared to thrombectomy plus stenting. 1, 6

• The anatomic compression persists despite anticoagulation, making mechanical relief essential 7
• Multiple case reports document recurrent DVT despite full anticoagulation when the mechanical obstruction is not addressed 2, 3

Do Not Delay Intervention

Early thrombus removal within 14 days yields optimal outcomes; delayed intervention reduces the effectiveness of thrombolysis 7

Recognize Stent Complications

• Stent fracture occurs in approximately 1% of cases and can be managed by implanting a second stent 7
• In pregnant patients with prior iliac vein stents, mechanical deformation may occur late in pregnancy but typically resolves spontaneously postpartum without clinical sequelae 7
• One case report documented catastrophic stent migration into the arterial system, though this is extremely rare 2

Special Consideration for Pregnancy

• LMWH is the anticoagulant of choice in pregnant or postpartum women, as warfarin causes embryopathy between 6–12 weeks' gestation 4
• Among 62 women with left iliac vein stents who received LMWH prophylaxis during pregnancy, none experienced recurrent VTE 7