What is the management approach for a young to middle-aged woman with suspected May-Thurner syndrome and a history of deep vein thrombosis (DVT)?

Management of May-Thurner Syndrome with Deep Vein Thrombosis

For a young to middle-aged woman with suspected May-Thurner syndrome and DVT, endovascular intervention with catheter-directed thrombolysis followed by iliac vein stenting is the preferred treatment approach, combined with systemic anticoagulation. 1, 2

Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis with appropriate imaging:

• Duplex ultrasound is the first-line test to diagnose DVT, though it may not adequately visualize iliac vein compression 1
• CT venography or MR venography should be performed when May-Thurner syndrome is suspected to directly visualize the compression of the left common iliac vein by the overlying right common iliac artery 1
• Suspect May-Thurner syndrome particularly in patients with left-sided iliofemoral DVT that is unprovoked or recurrent 1, 3, 4, 5

Initial Anticoagulation Management

Begin immediate anticoagulation therapy:

• Start low molecular weight heparin (LMWH) or unfractionated heparin immediately upon diagnosis 6, 2
• LMWH is superior to unfractionated heparin for initial DVT treatment, particularly for reducing mortality and major bleeding risk 6
• Transition to long-term oral anticoagulation with warfarin (target INR 2.0-3.0) overlapped with initial anticoagulant for minimum 5 days and until INR >2.0 for at least 24 hours, or consider direct oral anticoagulants (DOACs) as an alternative 2

Endovascular Intervention Strategy

The mechanical compression in May-Thurner syndrome requires more than anticoagulation alone:

• Catheter-directed thrombolysis (CDT) or pharmacomechanical catheter-directed thrombolysis (PCDT) is recommended for iliofemoral DVT to prevent post-thrombotic syndrome 1, 2, 4
• Angioplasty and stenting of the compressed iliac vein should be performed during the endovascular procedure to address the underlying mechanical compression 1, 2
• This combined approach significantly reduces the rate of early rethrombosis compared to thrombus removal alone 1
• For patients with limb-threatening circulatory compromise (phlegmasia cerulea dolens), urgent CDT or PCDT is mandatory 1, 2

The evidence strongly supports endovascular stenting as it addresses the anatomical cause rather than just treating the thrombotic consequence. Studies demonstrate good outcomes in maintaining venous patency with this approach 1.

Duration of Anticoagulation

Anticoagulation duration depends on the clinical context:

• Minimum 3 months of anticoagulation is required for all patients with DVT 6, 2
• For unprovoked DVT (which May-Thurner syndrome typically presents as), extended-duration therapy beyond 12 months should be strongly considered, as it decreases the relative risk for recurrence by 64% to 95% 6
• The American Society of Hematology guidelines support extended anticoagulation for unprovoked VTE given the substantial benefit 6

Adjunctive Measures to Prevent Post-Thrombotic Syndrome

Beyond anticoagulation and stenting:

• Compression stockings should be initiated within 1 month of diagnosis of proximal DVT and continued for a minimum of 1 year 6
• This intervention markedly reduces the incidence and severity of post-thrombotic syndrome 6
• Proper treatment with stenting reduces the risk of post-thrombotic syndrome and improves quality of life 1

Critical Pitfalls to Avoid

Several important considerations in managing May-Thurner syndrome:

• Anticoagulation alone is insufficient to prevent recurrence in May-Thurner syndrome because it does not address the mechanical compression 4
• Failure to diagnose May-Thurner syndrome leads to recurrent DVT despite adequate anticoagulation 3, 5
• Consider May-Thurner syndrome in any young woman with left-sided DVT, as it is found in 22% of cadavers but causes <5% of lower extremity venous disorders 4
• Greater than 70% compression is needed to cause DVT 4
• In rare refractory cases with continued thrombosis despite stenting and anticoagulation, dual antiplatelet therapy (aspirin and clopidogrel) combined with LMWH may be necessary 3

Follow-Up Monitoring

After intervention:

• Regular duplex ultrasound should be performed to evaluate venous patency and stent function 2
• Monitor for extension into the deep venous system or stent thrombosis 2
• Most diagnoses of post-thrombotic syndrome occur within the first 2 years after DVT 6

Special Population: Pregnancy and Postpartum

May-Thurner syndrome can present in the postpartum period:

• The hypercoagulable state of pregnancy and puerperium further predisposes to thrombus formation 7
• LMWH is the anticoagulant of choice in pregnant or postpartum women, as warfarin crosses the placenta and causes embryopathy between 6-12 weeks' gestation 6
• DVT in the postpartum period should not always be attributed solely to pregnancy-related hypercoagulability; consider underlying anatomical causes like May-Thurner syndrome 7