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cardio.dvt.factor-v-leiden.v1

Factor V Leiden thrombophilia DVT (heterozygous or homozygous)

cardiologyacuteadultacuteinpatienttransitionoutpatient
Start encounter →Print handoutPRODUCTION

Phase E variant of cardio.dvt.core.v1 — narrowed to Factor V Leiden heritable thrombophilia (G1691A point mutation; APC resistance phenotype). Inherits diagnostic arc and DOAC chronic regimen from parent via routing; specializes for the zygosity-driven AC-duration decision, family-screening pathway, and pregnancy implications. Manifest pointer reuses cardio.dvt.core.v1 manifest. Design-brief pointer reuses parent (FVL-specific differences documented inline). Distinguishing features vs generic DVT: testing indication per ASH 2018 (young <45, unprovoked, recurrent, strong family hx, unusual site); thrombophilia panel timing matters (send BEFORE first AC dose or off AC at 3 mo); zygosity drives duration — heterozygous + provoked = 3 mo then stop; heterozygous + unprovoked = individualized lean indefinite if low bleed (HAS-BLED 0-1); homozygous = indefinite. DOACs first-line for FVL alone (AMPLIFY/EINSTEIN/Hokusai subgroups). Warfarin preferred if concurrent APS triple-positive (TRAPS 2018). Pregnancy: heterozygous alone low-risk (no LMWH unless prior VTE/family hx); homozygous high-risk (antepartum + 6-wk postpartum LMWH per ASH 2018). Family screening for first-degree relatives only if result will change management (ACMG / ASH 2018) — typical triggers are pre-OCP, pre-pregnancy, pre-high-risk-surgery. Status INTEGRATED. Authored 2026-05-15 by shard-06-cardio-acute as Factor V Leiden thrombophilia DVT variant.

Entry points (4)

  • symptom
    Unilateral leg swelling or proven DVT in patient with strong family history of VTE (first-degree relative under 50) — pretest probability for heritable thrombophilia including FVL is elevated
    unilateral_leg_swelling_with_family_history_vte
  • history
    First VTE under age 45 with no provoking factor — ASH 2018 indication to consider heritable thrombophilia testing including FVL PCR
    first_vte_under_45_unprovoked
  • history
    Recurrent VTE with minor or no provoking factors — strong indication for thrombophilia evaluation and likely indefinite AC
    recurrent_vte_with_minor_or_no_triggers
  • history
    Cerebral venous, splanchnic, or upper-extremity thrombosis without obvious cause → broader thrombophilia panel including FVL
    unusual_site_thrombosis_with_thrombophilia_suspicion

Required inputs (11)

  • agerequired
    demographic • used at CONTEXT
    Age at first VTE drives testing indication (ASH 2018: under 45 with unprovoked); younger patients also have more lifetime AC exposure if indefinite AC chosen
  • sexrequired
    demographic • used at CONTEXT
    Female heterozygous FVL with OCP use has multiplicative risk; pregnancy planning is a major management decision point
  • family_vte_historyrequired
    history • used at CONTEXT
    First-degree relative with VTE under 50 strongly suggests heritable thrombophilia; informs first-degree relative screening counseling
  • provoking_factor_statusrequired
    history • used at CONTEXT
    Provoked (reversible) vs unprovoked drives AC duration even with FVL — provoked + heterozygous can stop at 3 mo if low-bleed-risk; unprovoked + heterozygous is debated
  • leg_swellingrequired
    symptom • used at ENTRY
    Cardinal symptom of proximal DVT
  • compression_usrequired
    imaging • used at INITIAL_WORKUP
    Initial confirmation of DVT location (proximal vs distal)
  • fvl_pcrrequired
    lab • used at BRANCHING_WORKUP
    Factor V Leiden PCR for G1691A point mutation; result determines zygosity (heterozygous vs homozygous) which drives AC duration and pregnancy plan
  • thrombophilia_panelrequired
    lab • used at BRANCHING_WORKUP
    Comprehensive thrombophilia panel: prothrombin G20210A, antiphospholipid antibodies (lupus anticoagulant + anti-cardiolipin + anti-β2-glycoprotein I, both ≥12 weeks apart), protein C, protein S, antithrombin; concurrent traits shift to indefinite AC and may change DOAC vs warfarin choice
  • creatininerequired
    lab • used at TREATMENT
    eGFR for DOAC dosing
  • cbcrequired
    lab • used at INITIAL_WORKUP
    Baseline platelet for AC and HIT screen during heparin exposure
  • bleed_riskrequired
    history • used at RED_FLAGS
    HAS-BLED + falls + GI bleed history drives indefinite-AC eligibility

12-phase flow (11)

  1. 1FRAME
    Factor V Leiden = G1691A → APC resistance phenotype; heterozygous ~5% European descent (3-8× VTE risk), homozygous ~0.02-0.06% (80× risk). Acute treatment same as parent; AC duration decision driven by zygosity + provoking factor + concurrent thrombophilia + bleed risk
    inputs: leg_swelling
    advance: FVL phenotype framed
  2. 2ENTRY
    Wells DVT score + compression US; document family history and age at first event; testing indication per ASH 2018 (under 45 unprovoked, strong family hx, recurrent, unusual site)
    inputs: family_vte_history, age
    advance: pretest probability + testing indication documented
  3. 3CONTEXT
    Provoking factor status; OCP / hormone use; pregnancy plans; family thrombophilia history; concurrent VTE risk factors; testing-impact-on-management discussion (ASH 2018 emphasizes only test if it will change management)
    inputs: sex, provoking_factor_status
    advance: context complete
  4. 4RED_FLAGS
    Concurrent PE; phlegmasia; absolute AC contraindication; ICH; concurrent APS with triple-positive serology (changes DOAC vs warfarin); pregnant with FVL homozygous (very high-risk)
    inputs: bleed_risk
    actions: pe_full, thrombocytopenia
    advance: critical features screened
  5. 5INITIAL_WORKUP
    Compression US (proximal vs distal); CBC + BMP + INR/PTT; D-dimer if pretest probability borderline; troponin + BNP if PE confirmed
    inputs: compression_us, cbc, creatinine
    actions: panel.cardiac, panel.renal
    advance: imaging confirms DVT
  6. 6BRANCHING_WORKUP
    Thrombophilia panel timing matters: send BEFORE starting AC (DOACs and warfarin interfere with protein C/S/AT assays and lupus anticoagulant); FVL PCR is unaffected by AC and can be sent any time. If panel sent post-AC, repeat critical interfered assays 2 weeks off AC at 3-mo decision point. Document zygosity result clearly
    inputs: fvl_pcr, thrombophilia_panel
    advance: zygosity + concurrent thrombophilia documented
  7. 7RISK_STRATIFICATION
    Wells DVT, HAS-BLED, eGFR; HERDOO2 for women with first unprovoked VTE; integrate zygosity + provoking factor + concurrent traits to choose AC duration: 3 mo if provoked + heterozygous + low-bleed-risk; INDEFINITE if homozygous, unprovoked + heterozygous (debated, leaning indefinite if low bleed), unprovoked + any concurrent trait, recurrent, or unusual-site
    inputs: bleed_risk
    actions: calc.wells_dvt, calc.has_bled
    advance: AC duration plan documented with rationale
  8. 8TREATMENT
    Acute AC: DOAC first-line (apixaban 10/7/5 or rivaroxaban 15/21/20 or edoxaban after LMWH bridge); LMWH bridge if APS pending workup or pregnancy; WARFARIN preferred if APS triple-positive confirmed (TRAPS PMID 30002145). Extended-phase: apixaban 2.5 mg BID OR rivaroxaban 10 mg daily acceptable for FVL alone per AMPLIFY-EXT / EINSTEIN-CHOICE
    inputs: creatinine, bleed_risk
    advance: acute AC + extended-phase plan documented
  9. 9DISPOSITION
    Outpatient for uncomplicated proximal DVT; admit if concurrent PE intermediate-high risk, phlegmasia, or social barriers
    advance: disposition documented
  10. 10MONITORING
    CBC + creatinine at 4 weeks then quarterly during indefinite AC; bleed surveillance; PTS Villalta at 3/6/12 mo; re-evaluate AC continuation annually for indefinite patients (HAS-BLED can rise with age and creates a stop trigger)
    actions: panel.cardiac
    advance: monitoring schedule documented
  11. 11FOLLOWUP
    Genetic counseling for proband; first-degree relative screening discussion (ACMG / ASH 2018 — test only if result will change management, e.g. pre-OCP, pre-pregnancy, pre-high-risk-surgery); pregnancy planning for women (LMWH if homozygous or prior VTE); OCP discontinuation; address modifiable risk factors lifetime
    advance: genetic counseling + reproductive plan + family screening pathway documented