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cardio.dvt.may-thurner.v1

May-Thurner syndrome (left iliac vein compression DVT)

cardiologyacuteadultacuteinpatienttransitionoutpatient
Start encounter →Print handoutPRODUCTION

Phase E variant of cardio.dvt.core.v1 — narrowed to May-Thurner syndrome (anatomic compression of left common iliac vein by right common iliac artery against L5). Inherits diagnostic arc and DOAC chronic regimen from parent via routing; specializes for the combined treatment paradigm: AC + catheter-directed thrombolysis (within 14 d) + iliac venous stenting under IVUS guidance per Hofmann 2024. Manifest pointer reuses cardio.dvt.core.v1 manifest. Design-brief pointer reuses parent (MTS-specific differences documented inline). Distinguishing features vs generic proximal DVT: young woman with left-sided iliofemoral DVT (often "unprovoked" or with minor trigger like OCP / post-partum); mandatory venography + IVUS for stenosis grading; iliac venous stent placement (Wallstent or Vici / Venovo / Abre); lifetime duplex US for stent patency; chronic AC duration debated — ≥3 mo if provoked + patent stent vs indefinite if unprovoked or persistent stenosis; OCP discontinuation key. Status INTEGRATED. Authored 2026-05-14 by shard-06-cardio-acute as MTS variant.

Entry points (4)

  • symptom
    Left whole-leg swelling + thigh/groin pain in young woman (age 20–45) — pretest probability for May-Thurner is high; right-side DVT in this demographic should not assume MTS
    left_sided_iliofemoral_swelling_young_woman
  • imaging
    Compression US shows non-compressible left common iliac / external iliac / common femoral vein → confirm proximal DVT and proceed to venography for MTS evaluation
    us_left_iliofemoral_thrombus
  • history
    Left iliofemoral DVT with minor or no provoking factor (OCP, post-partum, recent surgery, immobility) — anatomic substrate (Cockett lesion) likely contributing; mandate venography + IVUS during CDT
    unprovoked_or_minor_trigger_left_dvt
  • symptom
    Recurrent left-sided DVT despite therapeutic AC — strong suspicion of underlying iliac compression requiring stent
    recurrent_left_lower_extremity_dvt

Required inputs (9)

  • agerequired
    demographic • used at CONTEXT
    Young women (20–45) have highest MTS prevalence; older patients may have additive degenerative compression
  • sexrequired
    demographic • used at CONTEXT
    Female:male prevalence ~3-4:1; OCP and post-partum hormone milieu compounds anatomic substrate
  • leg_swelling_leftrequired
    symptom • used at ENTRY
    Left-side predilection is the MTS hallmark; right-side DVT lowers anatomic suspicion (consider IVC compression, retroperitoneal mass, or generic DVT)
  • compression_usrequired
    imaging • used at INITIAL_WORKUP
    Initial confirmation of iliofemoral DVT; US has limited iliac visualization → triggers venography or MRV for stenosis grading
  • venography_or_mrvrequired
    imaging • used at BRANCHING_WORKUP
    Venography (gold standard) or MRV grades the iliac stenosis; IVUS during venogram is now considered the most accurate intra-procedural sizing tool (CIRSE 2014; Hofmann 2024)
  • creatininerequired
    lab • used at TREATMENT
    eGFR for DOAC dosing + contrast load during venography; CKD-EPI 2021 race-free preferred
  • cbcrequired
    lab • used at INITIAL_WORKUP
    Baseline Hgb + platelet for AC + thrombolytic-bleed risk
  • hormone_userequired
    history • used at CONTEXT
    OCP, hormone replacement, recent pregnancy/postpartum compound MTS risk; OCP discontinuation is a key non-pharm intervention
  • bleed_riskrequired
    history • used at RED_FLAGS
    HAS-BLED + recent surgery + falls history determines AC + CDT eligibility

12-phase flow (11)

  1. 1FRAME
    May-Thurner = anatomic compression of left common iliac vein by overlying right common iliac artery; presents as left iliofemoral DVT in young women; treatment requires AC + thrombus removal (CDT) + venous stent to address substrate; route to cardio.dvt.core.v1 for diagnostic arc + DOAC chronic regimen
    inputs: leg_swelling_left
    advance: left iliofemoral DVT confirmed
  2. 2ENTRY
    Wells score → US directly if high pretest probability; if left-sided + young woman + minor/no provoker, anatomic suspicion is high
    inputs: age, sex
    advance: pretest probability assigned and laterality confirmed
  3. 3CONTEXT
    Hormone use (OCP, post-partum), recent surgery, prior left-side DVT, family hx, thrombophilia history; lifetime activity (athletes can have additive compression syndromes)
    inputs: hormone_use, creatinine
    advance: context complete
  4. 4RED_FLAGS
    Phlegmasia cerulea dolens from acute occlusive iliofemoral DVT; concurrent PE; absolute AC contraindication; severe pain or compartment syndrome features
    inputs: bleed_risk
    actions: phlegmasia_pathway, concurrent_pe_screen
    advance: limb-threatening features screened
  5. 5INITIAL_WORKUP
    Compression US (femoral + popliteal) confirms thrombus location; CBC + BMP + INR/PTT; D-dimer if pretest probability low-intermediate; CT abdomen/pelvis with contrast can demonstrate iliac compression incidentally
    inputs: compression_us, cbc, creatinine
    actions: panel.cardiac, panel.renal
    advance: imaging confirms left iliofemoral DVT
  6. 6BRANCHING_WORKUP
    Catheter venography (gold standard for stenosis grading) + IVUS during CDT for accurate iliac sizing (CIRSE 2014; Hofmann 2024); MRV non-invasive alternative; document compression severity, presence of collaterals, and contralateral patency
    inputs: venography_or_mrv
    advance: iliac stenosis graded and stent plan documented
  7. 7RISK_STRATIFICATION
    HAS-BLED for AC + thrombolytic bleed risk; iliofemoral severity for CDT prioritization (ATTRACT iliofemoral subgroup PMID 29211671); HERDOO2 for women with first unprovoked VTE to inform extended-AC after stent
    inputs: bleed_risk
    actions: calc.has_bled
    advance: CDT + stent + AC duration plan documented
  8. 8TREATMENT
    Combined treatment: (1) AC initiated immediately (DOAC apixaban 10/7/5 or enoxaparin bridge); (2) CDT within 14 d via pharmacomechanical thrombolysis (alteplase 0.5–1 mg/h ×12–24 h, mechanical thrombectomy adjunct); (3) iliac venous stent (Wallstent or Vici/Venovo/Abre) across the Cockett lesion under IVUS guidance; chronic AC ≥3 mo if provoked + stent patent, indefinite if unprovoked or persistent stenosis (Hofmann 2024)
    inputs: creatinine, bleed_risk
    advance: AC + CDT + stent decisions documented
  9. 9DISPOSITION
    ICU during/after CDT for limb perfusion + bleed monitoring; step-down to floor when thrombolytic complete + stent placed + AC stable; outpatient when oral DOAC + stent patency confirmed
    advance: unit assigned + post-stent AC plan documented
  10. 10MONITORING
    Stent patency surveillance via duplex US at 1, 3, 6, 12 mo then annually (in-stent re-thrombosis is the main long-term concern); compression stockings 30–40 mmHg for PTS prevention; PTS Villalta scale
    actions: panel.cardiac
    advance: stent surveillance schedule documented
  11. 11FOLLOWUP
    Lifetime stent surveillance; AC duration reassessment based on stent patency + provoking-factor reversibility; OCP discontinuation discussion; pregnancy planning counseling (LMWH bridge if pregnancy desired)
    advance: extended-AC + lifestyle plan documented