Thrombophilia / DVT / HITUrgent

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Unilateral leg swelling/pain

Calculators:
  1. Best initial: Lower-extremity duplex ultrasound
  2. Treat DVT: DOAC first-line — apixaban 10 mg BD ×7 d → 5 mg BD, or rivaroxaban 15 mg BD ×21 d → 20 mg OD (no LMWH bridge). LMWH→warfarin (INR 2–3) if DOAC unsuitable (antiphospholipid syndrome, mechanical valve, severe renal failure CrCl <15–30); 3 mo if provoked, then reassess (ASH 2020; AHA/ACC 2026)
  3. HIT (platelets ↓>50% day 5–10 + thrombosis) → STOP all heparin → Argatroban/fondaparinux; a DOAC (rivaroxaban/apixaban) is an accepted alternative in stable HIT (ASH 2018)

Order set

  • Duplex ultrasound
  • D-dimer (if low pretest)
  • FBC (platelet trend)
  • Baseline coags

Criteria

AdmitExtensive VTE, PE, or HIT with thrombosis
ICUMassive PE
DischargeAnticoagulated, HIT agent if applicable, duration defined

Never

  • Order thrombophilia workup for a first clot
  • Give warfarin alone in acute HIT (→ skin necrosis)
  • Thrombophilia testing during the acute event or on anticoagulation (unreliable)
Clinical detail — differentials, red flags, pitfalls, disposition
Red flags
  • Signs of PE
  • Phlegmasia
  • HIT with thrombosis
Differentials
  • Cellulitis
  • Ruptured Baker cyst
  • Post-thrombotic syndrome
Common mistakes
  • Thrombophilia testing for first provoked clot
  • Warfarin alone in acute HIT
Disposition & follow-up

Anticoagulate; HIT → non-heparin agent; provoked VTE 3 months.

Discharge package
MedicationsAnticoagulation (duration per provocation); non-heparin agent in HIT
Follow-upAnticoagulation clinic; review at 3 months
Warning symptomsLeg swelling, chest pain/SOB, bleeding
💊 Treatment detail — doses & preparation
EnoxaparinLMW heparin
DoseTreatment: 1 mg/kg SC q12h (or 1.5 mg/kg OD). Prophylaxis: 40 mg SC OD
PreparationPre-filled syringes 20–150 mg; inject SC abdomen, do not expel air bubble
MonitorAnti-Xa if renal failure/pregnancy; platelets (HIT); renal dosing
ApixabanDOAC (anti-Xa)
Dose5 mg BD (2.5 mg BD if ≥2 of: age ≥80, weight ≤60 kg, Cr ≥133). PE/DVT: 10 mg BD ×7 d then 5 mg BD
Preparation2.5/5 mg tablets (crushable)
MonitorBleeding, renal function; no routine monitoring
RivaroxabanDOAC (anti-Xa)
DosePE/DVT: 15 mg BD ×21 d then 20 mg OD with food. AF: 20 mg OD (15 mg if CrCl 15–49)
Preparation10/15/20 mg tablets; take 15/20 mg with food
MonitorBleeding, renal function
WarfarinVKA anticoagulant
DoseLoad 5 mg OD ×2 d then INR-guided; target INR 2–3 (valves may differ)
Preparation0.5/1/3/5 mg tablets — colour-coded
MonitorINR q2–3 d until stable; diet consistency, interactions (amiodarone, antibiotics)
Argatrobandirect thrombin inhibitor
Dose2 mcg/kg/min IV, titrate aPTT 1.5–3× — HIT anticoagulation
Preparation250 mg in 250 mL NS (1 mg/mL) via pump; no bolus
MonitoraPTT q2h initially; falsely elevates INR when bridging
📖 ASH / NICE VTE; ASH HITReviewed July 2026

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