วันพฤหัสบดีที่ 14 พฤษภาคม พ.ศ. 2569

May-Thurner Syndrome (MTS)

May-Thurner Syndrome (MTS)

Overview

May-Thurner syndrome (MTS) =
iliac vein compression syndrome

เกิดจาก:

  • extrinsic venous compression
    ใน iliocaval territory

Classic lesion:

  • left common iliac vein
    ถูกกดโดย
  • right common iliac artery
    against lumbar vertebra

Clinical importance

สัมพันธ์กับ:

  • left iliofemoral DVT
  • chronic venous hypertension
  • post-thrombotic syndrome (PTS)

ควรคิดถึงเสมอเมื่อ:

  • young female
  • unilateral left leg swelling
  • extensive proximal DVT

Pathophysiology

Chronic pulsatile arterial compression →

  • endothelial injury
  • venous spur formation
  • venous stenosis
  • venous stasis
  • thrombosis

Classic anatomy

Left common iliac vein compression by right common iliac artery

Epidemiology

  • many patients asymptomatic
  • significant iliac stenosis (>50%) พบได้ ~25% ในบาง imaging studies
  • symptomatic MTS ประมาณ 1–5% ของ venous disorders

Risk factors

  • female sex
  • postpartum/multiparity
  • oral contraceptives
  • dehydration
  • hypercoagulable state
  • scoliosis
  • radiation exposure

Clinical presentations

1. Acute DVT presentation

Typical:

  • acute unilateral left leg swelling
  • pain
  • extensive iliofemoral DVT

2. Chronic venous hypertension

  • chronic edema
  • heaviness
  • venous claudication
  • skin discoloration
  • venous ulcer

3. Pelvic congestion syndrome

โดยเฉพาะใน female patients

Venous claudication

Definition:

  • thigh/leg pain and tightness with exercise
  • improves with rest/elevation

พบได้ถึง:
Venous claudication prevalence 85%

Important clinical clues

ควรสงสัย MTS หากมี:

  • left-sided proximal DVT
  • whole-leg swelling
  • recurrent ipsilateral DVT
  • persistent symptoms despite anticoagulation
  • post-thrombotic syndrome
  • visible abdominal/groin collaterals

Diagnosis

Initial approach

ประเมิน DVT ก่อน:

  • Wells score
  • D-dimer
  • duplex ultrasound

Duplex ultrasound

Useful for:

  • proximal DVT
  • iliocaval obstruction clues

Suggestive findings:

  • absent respiratory variation
  • narrowed iliac vein
  • sluggish flow
  • poor augmentation

Peak vein velocity (PVV)

Significant stenosis if:

PVV gradient >2.0

CT/MR venography

Sensitivity/specificity:

95%

Useful for:

  • anatomy
  • collaterals
  • alternative causes of compression

Gold standard

Intravascular ultrasound (IVUS)

Sensitivity/specificity:

98%

Advantages:

  • defines spur morphology
  • accurate stenosis severity
  • guides stenting
  • evaluates stent expansion

Hemodynamic confirmation

Iliac vein pressure gradient significant if:

Pressure gradient > 2 mmHg

Differential diagnosis

  • uncomplicated DVT
  • chronic venous insufficiency
  • lymphedema
  • pelvic mass
  • retroperitoneal fibrosis
  • uterine enlargement
  • aneurysm
  • osteophyte compression

Treatment overview

Depends on:

  • presence of DVT
  • severity of symptoms

Nonthrombotic MTS

Mild symptoms (CEAP 1–3)

Conservative:

  • compression stockings

Moderate/severe symptoms (CEAP 4–6)

Preferred:

  • angioplasty + stenting

Important:

  • angioplasty alone insufficient
  • recurrence high without stent

Thrombotic MTS

Initial treatment

  • full anticoagulation

then:

  • catheter-directed thrombolysis (CDT)
    หรือ
  • pharmacomechanical thrombectomy

Key principle

หลัง thrombus removal:
ต้องค้นหา underlying stenosis ด้วย IVUS

ถ้ามี stenosis:
→ angioplasty + stenting

Outcomes with treatment

Successful treatment:
PTS <10%

Without treatment:
PTS ประมาณ

Untreated PTS risk approx 80-90%

Contraindication to thrombolysis

ใช้:

  • mechanical thrombectomy

Options:

  • rheolytic thrombectomy
  • rotational thrombectomy
  • suction thrombectomy

Surgery

Reserved for:

  • failed endovascular therapy
  • unsuitable anatomy
  • severe chronic occlusion

Examples:

  • Palma-Dale bypass
  • venous reconstruction

Post-procedure management

Compression stockings

Recommended:

  • 30–40 mmHg

Anticoagulation

Follow standard VTE guidelines

After stenting

reasonable to add:

  • antiplatelet therapy
    หาก bleeding risk ต่ำ

Complications of intervention

  • stent migration
  • restenosis
  • iliac vein rupture
  • contralateral iliac vein thrombosis
  • arterial erosion

Evidence summary

CDT + stenting

Benefits:

  • improved venous patency
  • reduced PTS
  • better symptom relief
  • improved quality of life

ATTRACT trial pearl

Routine CDT for all proximal DVT:

  • not beneficial overall

แต่ subgroup:

  • iliofemoral DVT
    อาจ benefit มากกว่า

Patency rates after stenting

Primary patency:
~61–92% at 1 year

Secondary patency:
up to 98%

Clinical pearls

  • think MTS in young female with left iliofemoral DVT
  • whole-leg swelling + proximal DVT strongly suggestive
  • IVUS = current diagnostic standard
  • angioplasty alone inadequate → stenting usually required
  • anticoagulation alone often suboptimal in thrombotic MTS
  • untreated MTS → very high PTS risk
  • successful stenting markedly improves symptoms/patency
  • persistent unilateral symptoms after DVT treatment → reassess for MTS
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