May-Thurner Syndrome and Venous Stenting: Diagnosis, Management, and Long-Term Outcomes

May-Thurner Syndrome (MTS), also known as iliac vein compression syndrome or Cockett’s syndrome, represents a significant anatomical variant that can lead to substantial venous morbidity. This condition, characterized by compression of the left common iliac vein by the overlying right common iliac artery against the lumbar vertebrae, affects an estimated 20-30% of the general population anatomically, though it becomes clinically significant in a smaller subset. With the advancement of endovascular techniques and dedicated venous stents, the management of symptomatic May-Thurner Syndrome has evolved dramatically over the past two decades. This comprehensive guide explores the pathophysiology, diagnostic approaches, contemporary management strategies, and long-term outcomes of venous stenting for May-Thurner Syndrome.

Pathophysiology and Clinical Presentation

Anatomical Basis

May-Thurner Syndrome results from a specific anatomical relationship:

• Compression mechanism: Right common iliac artery crosses over and compresses the left common iliac vein against the fifth lumbar vertebra
• Chronic pulsatile compression: Leads to intimal hyperplasia, fibrosis, and spur formation
• Venous outflow obstruction: Results in increased venous pressure and impaired drainage
• Collateral formation: Development of pelvic and paravertebral collaterals to compensate

Variants and Related Syndromes

Several anatomical variants exist:

• Classic May-Thurner: Left common iliac vein compression (most common)
• Right-sided variant: Right common iliac vein compression (rare)
• Bilateral compression: Both iliac veins compressed (uncommon)
• Related conditions:
• Nutcracker syndrome (left renal vein compression)
• Popliteal entrapment syndrome
• Retroaortic left renal vein compression

Klinická prezentace

Symptoms vary widely in severity and presentation:

• Asymptomatic compression: Most common, found incidentally
• Mild to moderate symptoms:
• Left leg swelling (unilateral edema)
• Heaviness or aching in the left leg
• Varicose veins, predominantly left-sided

• Venous claudication with activity

• Severe manifestations:

• Acute iliofemoral deep vein thrombosis (DVT)
• Post-thrombotic syndrome
• Venous ulceration

• Phlegmasia cerulea dolens (rare)

• Associated conditions:

• Pelvic congestion syndrome
• Recurrent superficial thrombophlebitis
• Venous aneurysms

Risk Factors for Symptomatic Disease

Several factors increase the likelihood of developing symptoms:

• Female gender: 2-3 times more common in women
• Age: Typically presents in 20s-40s
• Těhotenství: Hormonal changes and increased venous pressure
• Hormonal contraception: Increased thrombotic risk
• Thrombophilia: Inherited or acquired hypercoagulable states
• Prolonged immobility: Travel, hospitalization
• Dehydration: Increases blood viscosity
• Previous venous thromboembolism: History of DVT or PE

Diagnostic Approach

Accurate diagnosis requires a systematic approach:

Clinical Assessment

• Historie: Focused on venous symptoms, risk factors, previous DVT
• Physical examination: Asymmetric edema, varicosities, skin changes
• Clinical probability assessment: CEAP classification, Villalta score
• Differential diagnosis: Other causes of unilateral leg swelling

Non-invasive Imaging

• Duplex ultrasound:
• First-line imaging modality
• Limitations in visualizing iliac veins
• May show increased velocity, turbulence, or collaterals

• Limited sensitivity for MTS (30-50%)

• CT venography:

• Excellent visualization of iliac vessels
• Demonstrates compression and collaterals
• Allows assessment of surrounding structures

• Requires contrast and radiation exposure

• MR venography:

• No radiation exposure
• Excellent soft tissue contrast
• Demonstrates compression and collaterals
• Limitations in patients with metallic implants

Invasive Diagnostic Modalities

• Conventional venography:
• Traditional gold standard
• Limited by two-dimensional projection
• May underestimate degree of compression

• Allows pressure gradient measurement

• Intravascular ultrasound (IVUS):

• Current gold standard for diagnosis
• Cross-sectional imaging from within the vessel
• Quantifies degree of compression accurately
• Detects subtle lesions missed by venography
• Guides intervention and stent sizing

Diagnostic Criteria

While no universally accepted criteria exist, common parameters include:

• Anatomical criteria:

• 50% reduction in cross-sectional area on IVUS

• 2 mmHg pressure gradient across lesion

• Significant collateral formation

• Visible compression on cross-sectional imaging

• Clinical correlation:

• Symptoms consistent with venous hypertension
• Absence of alternative explanations
• Response to therapeutic interventions

Management Approaches

Treatment strategies depend on symptom severity and presentation:

Conservative Management

For asymptomatic or mildly symptomatic patients:

• Compression therapy:
• Graduated compression stockings (20-30 mmHg)
• Improves symptoms but doesn’t address underlying compression

• Limited long-term effectiveness

• Exercise and lifestyle modifications:

• Regular physical activity
• Weight management
• Elevation of legs when seated

• Avoidance of prolonged standing/sitting

• Anticoagulation:

• For patients presenting with acute DVT
• Does not address underlying anatomical issue
• Risk of recurrent thrombosis remains high

Endovascular Intervention

The mainstay of treatment for symptomatic MTS:

• Indications for intervention:
• Symptomatic venous outflow obstruction
• Acute iliofemoral DVT with underlying MTS
• Recurrent DVT despite adequate anticoagulation

• Severe post-thrombotic syndrome

• Procedural approach:

• Access: Typically ipsilateral femoral or popliteal vein
• Crossing: Often straightforward in non-thrombotic cases
• Imaging: IVUS essential for accurate diagnosis and sizing
• Pre-dilation: Balloon angioplasty to prepare lesion
• Stent selection: Dedicated venous stents preferred

• Post-dilation: Ensure full expansion and apposition

• Technical considerations:

• Stent diameter: Typically 14-18mm based on IVUS measurements
• Stent length: Coverage of entire compressed segment
• Landing zones: Extension into IVC often necessary
• Overlap technique for multiple stents when required

Management of Acute Iliofemoral DVT with MTS

Special considerations apply:

• Catheter-directed thrombolysis:
• Dissolves acute thrombus
• Reveals underlying compression

• Reduces post-thrombotic syndrome risk

• Pharmacomechanical thrombectomy:

• Rapid thrombus removal
• Reduced lytic dose and time

• Various devices available (AngioJet, Indigo, etc.)

• Staged approach:

• Thrombus removal first
• Followed by venous stenting
• Single-session procedures increasingly common

Anticoagulation and Antithrombotic Therapy

Critical component of management:

• Post-procedural anticoagulation:
• Typically 3-6 months minimum
• Extended duration in high-risk patients

• Options include warfarin, DOACs, or LMWH

• Antiplatelet therapy:

• Often added to anticoagulation initially
• Single antiplatelet may be continued long-term

• Limited evidence base for optimal regimen

• Long-term management:

• Risk stratification for recurrent thrombosis
• Consideration of thrombophilia testing
• Individualized duration of therapy

Clinical Outcomes of Venous Stenting for MTS

Growing evidence supports endovascular management:

Technical Success

• Procedural success rates: 95-100% in most series
• Immediate hemodynamic improvement: Normalization of pressure gradients
• Rapid symptom relief: Often within 24-48 hours
• Low periprocedural complication rates: 1-3%

Patency Rates

• Primary patency:
• Non-thrombotic MTS: 90-95% at 1 year, 85-90% at 3 years

• Post-thrombotic MTS: 70-85% at 1 year, 60-75% at 3 years

• Secondary patency (after reintervention):

• Non-thrombotic MTS: 95-100% at 3 years

• Post-thrombotic MTS: 85-95% at 3 years

• Factors affecting patency:

• Thrombotic vs. non-thrombotic presentation
• Stent type and sizing
• Extension into inferior vena cava
• Inflow and outflow status
• Anticoagulation regimen

Clinical Improvement

• Symptom resolution:
• Edema improvement: 70-90% of patients
• Pain reduction: 65-85% of patients

• Venous claudication: 80-95% improvement

• Quality of life outcomes:

• Significant improvements in venous disease-specific QOL measures
• Return to normal activities in majority of patients

• High patient satisfaction rates

• Ulcer healing:

• 60-80% healing rates for venous ulcers
• Reduced recurrence compared to conservative therapy

Komplikace a jejich řešení

• Early complications:
• Access site issues (1-3%)
• Bleeding (1-2%)
• Early thrombosis (2-5%)

• Stent malposition (rare)

• Late complications:

• In-stent restenosis (5-15%)
• Stent fracture (rare with dedicated venous stents)
• Contralateral DVT (1-2%)

• Recurrent symptoms despite patent stent

• Management of complications:

• Surveillance protocols with duplex ultrasound
• Early reintervention for restenosis
• Catheter-directed thrombolysis for acute thrombosis
• Extension stenting for edge stenosis

Zvláštní ohledy

Pregnancy and MTS

Important considerations for women of childbearing age:

• Pregnancy risk:
• Increased DVT risk during pregnancy and postpartum
• May unmask previously asymptomatic MTS

• Management challenges due to radiation concerns

• Pre-pregnancy stenting:

• Consider for women with symptomatic MTS planning pregnancy
• Reduces risk during pregnancy

• Requires careful anticoagulation planning

• Management during pregnancy:

• Conservative approach preferred when possible
• Intervention reserved for severe cases
• LMWH anticoagulation when indicated

Pediatric MTS

Rare but important considerations:

• Presentation: Often with extensive DVT
• Diagnostic challenges: Radiation concerns, vessel size
• Treatment: Similar principles but size-appropriate devices
• Long-term considerations: Growth, future pregnancies

Bilateral Iliac Vein Compression

Management of complex cases:

• Diagnostic challenges: Determining clinical significance
• Intervention approach: Often staged procedures
• Stenting considerations: Kissing stents vs. sequential approach
• Outcomes: Generally good but less data than unilateral cases

Budoucí směry

The field continues to evolve:

• Dedicated venous stent development:
• Optimization of radial force and flexibility
• Improved delivery systems

• Potential for drug-eluting technology

• Improved diagnostic modalities:

• Advanced IVUS capabilities
• Functional assessment tools

• Predictive modeling for intervention

• Standardized management protocols:

• Consensus guidelines for intervention
• Optimal anticoagulation regimens

• Surveillance recommendations

• Long-term outcome data:

• Ongoing registries and trials
• Quality of life assessments
• Analýzy nákladové efektivity

Zřeknutí se lékařské odpovědnosti

Důležité upozornění: This information is provided for educational purposes only and does not constitute medical advice. May-Thurner Syndrome can range from an incidental finding to a serious medical condition requiring intervention. The management approaches discussed should only be implemented under the guidance of qualified healthcare professionals after appropriate diagnostic assessment. Venous stenting procedures should be performed by specialists with specific training and experience in venous interventions. If you are experiencing symptoms such as leg swelling, pain, or have been diagnosed with deep vein thrombosis, please consult with a healthcare professional for proper evaluation and treatment recommendations. This article is not a substitute for professional medical advice, diagnosis, or treatment.

Závěr

May-Thurner Syndrome represents an important anatomical variant that can lead to significant venous morbidity when symptomatic. Modern diagnostic approaches, particularly intravascular ultrasound, have dramatically improved our ability to accurately identify and characterize iliac vein compression. Endovascular intervention with dedicated venous stents has emerged as the treatment of choice for symptomatic patients, with excellent technical success rates and durable clinical outcomes. While management challenges remain in certain populations and complex presentations, the overall prognosis for patients with May-Thurner Syndrome has improved substantially with contemporary approaches. Ongoing advances in stent technology, diagnostic capabilities, and management protocols continue to refine our approach to this important clinical entity.