Post-thrombotic syndrome prevention important for quality of life
Pediatrics
MTS in adolescents and young adults
Epidemiology
Increasingly recognized in adolescents, particularly female with OCP use or pregnancy
Median time from DVT to MTS diagnosis 0.65 months in adolescent series (Cohen 2021)
Accounts for significant proportion of unprovoked DVTs in young females
Clinical presentation
Left lower extremity swelling most common; may be attributed to musculoskeletal causes
High index of suspicion warranted in adolescent females with left-sided DVT
OCP initiation 5 weeks prior is a key trigger
Anticoagulation in pediatrics
LMWH preferred initially; dosing weight-based
Enoxaparin under 2 months: 1.5 mg/kg every 12 hours; adjust to anti-Xa 0.5-1.0 IU/mL
Enoxaparin 2 months and older: 1 mg/kg every 12 hours
DOACs: rivaroxaban and apixaban emerging options in adolescents; limited pediatric data
Duration: minimum 3-6 months; longer if persistent risk factors
Endovascular intervention in adolescents
Iliac vein stenting technically feasible and clinically effective
Primary patency 84-94% at 12 months in adolescent/young adult series (Bertino 2023)
One-stop mechanical thrombectomy plus stenting preferred to reduce PTS burden
Pediatric-specific stent sizing: use IVUS guidance; allow for growth in young adolescents
Background
Epidemiology
Prevalence and demographics
MTS accounts for 2-5% of all lower extremity DVTs
Likely underdiagnosed due to non-specific presentation and limited iliac vein visualization on routine ultrasound
Asymptomatic iliac vein compression present in approximately 22% of cadaveric studies
Female predominance: 78% of MTS patients in RIETE registry (Varona 2025)
Mean age 42 years vs 62 years in non-MTS DVT patients
Estrogen-exposed young women at highest risk
OCP use: DVT onset approximately 5 weeks after initiation (Murphy 2009)
Peripartum period represents peak risk window
RIETE registry findings
MTS independently predicts recurrent DVT: aHR 2.26 (95% CI 1.02-5.01)
Despite aggressive anticoagulation and endovascular therapy
Chronic thromboembolic pulmonary hypertension (CTEPH) association
MTS anatomy disproportionately identified in CTEPH patients (Al-Otaibi 2021)
Pathophysiology
Anatomical basis of MTS
Compression mechanism
Left common iliac vein compressed between overlying right common iliac artery and L5 vertebral body
Pulsatile arterial compression causes intimal injury and reactive intimal hyperplasia
Results in venous spur (Cockett spur) formation: intraluminal adhesion at compression site
Hemodynamic consequences
Venous outflow obstruction from the left lower extremity
Elevated left iliac vein pressure promotes venous stasis
Virchow's triad activation: stasis + endothelial injury + hypercoagulable state
Thrombosis cascade
Intimal hyperplasia and spur create nidus for thrombus formation
Compounding hypercoagulable states (OCP, pregnancy, thrombophilia) lower threshold for DVT
Thrombus propagates distally into femoral and popliteal veins
Chronic changes
Recurrent DVT leads to post-thrombotic syndrome via valvular incompetence
Persistent venous hypertension causes skin changes, ulceration, and pain
Collateral venous channels develop around obstruction (pelvic, retroperitoneal)
Anatomical variants
Right-sided compression (right iliac vein compressed by right internal iliac artery): rare
Atypical compression sites reported at L4 level or with accessory arteries
Therapeutic Considerations
Anticoagulation versus endovascular therapy
Anticoagulation alone is often insufficient
Mechanical compression persists; high recurrence risk without anatomical correction
aHR for recurrent DVT 2.26 despite anticoagulation in MTS (RIETE registry)
Endovascular intervention evidence
One-stop mechanical thrombectomy plus stenting: 81.5% vs 32% 6-month patency (Shao 2026)
PTS incidence 11% vs 76% with CDT alone in one-stop procedure cohort
ACR Appropriateness Criteria: CDT usually appropriate for symptomatic iliofemoral DVT
SIR Position Statement: endovascular stenting recommended for chronic iliofemoral obstruction (Vedantham 2023)
Post-thrombotic syndrome prevention
Graduated compression stockings reduce PTS risk after DVT
AHA Scientific Statement (Li 2025): open vein hypothesis supports early thrombus removal
ATTRACT trial: pharmacomechanical CDT did not reduce overall PTS but reduced severe PTS
Endovascular therapy for established PTS
NEJM RCT (Vedantham 2026): endovascular therapy for PTS under active study
Stent patency associated with improved PTS scores and quality of life
DOAC vs warfarin for long-term anticoagulation
DOACs preferred for convenience, predictable pharmacokinetics, fewer drug interactions
Warfarin preferred in antiphospholipid syndrome, significant renal impairment, or valvular disease
Antiplatelet therapy for stent patency
Antiplatelet agents associated with improved venous stent patency
Aspirin 81-100 mg daily added post-stenting in most protocols
Patient Discharge Instructions
copy discharge instructions
Discharge instructions for May-Thurner Syndrome
What is May-Thurner Syndrome
A vein in your pelvis called the left common iliac vein is squeezed between an artery and your spine
This compression slows blood flow and can cause blood clots in your left leg
You will need blood thinners and possibly a procedure to fix the compressed vein
Your medications
Take your blood thinner exactly as prescribed; do not skip doses
If on warfarin (Coumadin): follow-up for INR blood test as directed; target INR 2.0-3.0
If on rivaroxaban (Xarelto) or apixaban (Eliquis): take with food; do not stop without doctor's advice
Do not take aspirin, ibuprofen, or naproxen unless your doctor approves while on blood thinners
Activity and lifestyle
Walk regularly; avoid prolonged sitting or lying still (especially on flights or long car trips)
Elevate your left leg when resting to reduce swelling
Wear your compression stocking as prescribed (put on in the morning before getting up)
Avoid hot tubs, saunas, or extreme heat which can worsen swelling
Contraceptive and hormonal advice
Stop taking estrogen-containing birth control pills immediately; speak to your doctor about alternatives
Do not use hormone replacement therapy without discussing with your vascular specialist
Follow-up appointments
Return to your vascular surgeon or interventional radiologist within 1-2 weeks
Duplex ultrasound surveillance of your stent at 1, 3, 6, and 12 months if a stent was placed
IVC filter removal appointment at approximately 4 weeks if a filter was placed
Return to the emergency department immediately for
Worsening leg swelling, pain, or skin turning blue or purple
Shortness of breath, chest pain, or coughing up blood (possible blood clot in the lung)
Leg becomes cold, numb, or loses sensation
Unusual bleeding: blood in urine or stool, vomiting blood, or uncontrolled bleeding from cuts
Extreme weakness, dizziness, or fainting
References
Guidelines and Key Sources
Primary references
Chopard R, Albertsen IE, Piazza G. Diagnosis and Treatment of Lower Extremity Venous Thromboembolism: A Review. JAMA. 2020
Comprehensive review of DVT diagnosis and treatment; foundational evidence
Mousa AY, AbuRahma AF. May-Thurner Syndrome: Update and Review. Annals of Vascular Surgery. 2013. PMID 23850314
Epidemiology: approximately 22% cadaveric prevalence; 2-5% of DVTs attributed to MTS
Varona JF, et al. Clinical Characteristics and Impact of May-Thurner Syndrome in Patients With Proximal DVT: RIETE Registry. Angiology. 2025. PMID 41263573
78% female; mean age 42 years; aHR 2.26 for recurrent DVT
Murphy EH, et al. Symptomatic Iliofemoral DVT After OCP Use in Women With May-Thurner Syndrome. J Vasc Surg. 2009. PMID 19135831
Mean 5 weeks from OCP initiation to DVT onset
Cohen CT, et al. Diagnosis and Treatment of Adolescent May-Thurner Syndrome DVT. J Pediatr Hematol Oncol. 2021. PMID 33093351
Adolescent-specific data; 0.65 months median delay to diagnosis
Bertino FJ, et al. Iliac Vein Stent Placement in Adolescents and Young Adults With May-Thurner Syndrome. Cardiovasc Intervent Radiol. 2023. PMID 38097769
84-94% primary patency at 12 months in adolescent/young adult cohort
Shao T, et al. One-Stop AngioJet Mechanical Thrombectomy Combined With Iliac Vein Stenting in MTS. Medicine. 2026. PMID 41995556
81.5% vs 32% 6-month patency; PTS 11% vs 76%
Vedantham S, et al. SIR Position Statement on Endovascular Stenting for Chronic Iliofemoral Venous Obstruction. JVIR. 2023
Supports stenting for symptomatic chronic iliofemoral obstruction
Li W, Vedantham S, et al. AHA Scientific Statement: Revisiting the Open Vein Hypothesis. Circulation. 2025
Updated evidence supporting early thrombus removal to prevent PTS
Vedantham S, Kahn SR, Marston WA, et al. Endovascular Therapy for Post-Thrombotic Syndrome. NEJM. 2026
RCT evaluating endovascular therapy for established PTS
Guidance on imaging approach for chronic venous disease including MTS
Harbin MM, Lutsey PL. May-Thurner Syndrome: History of Understanding and Need for Defining Population Prevalence. J Thromb Haemost. 2020. PMID 31821707
Population prevalence challenges; importance of advanced imaging
Kahn SR, et al. AHA Scientific Statement on Post-Thrombotic Syndrome. Circulation. 2014
Evidence-based prevention and treatment of PTS
Al-Otaibi M, et al. May-Thurner Anatomy in CTEPH Patients. JACC Cardiovasc Interv. 2021. PMID 34503745
Association between MTS anatomy and chronic thromboembolic pulmonary hypertension
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