Deep vein thrombosis

Epidemiology & Risk Factors

Virchow’s Triad

1. Hypercoagulability: increased platelet adhesion, thrombophilia (e.g., factor V Leiden mutation), use of oral contraceptives, pregnancy, malignancy c
2. Endothelial damage: Inflammatory or traumatic vessel injuries can lead to activation of clotting factors through contact with exposed subendothelial collagen.
3. Venous stasis: varicosis, external pressure on the extremity, immobilization (e.g., hospitalization, bed rest, long flights or bus rides), local application of heat 

Subtypes and variants

Upper extremity deep vein thrombosis

• Etiology & Risk Factors:
  • Secondary (>80%): Central venous catheters (CVCs), PICC lines, pacemaker/ICD leads, active malignancy.
  • Primary (<20%): Paget-Schroetter syndrome (effort thrombosis from repetitive overhead arm exertion in young athletes) or Thoracic Outlet Syndrome (TOS).
• Clinical Features:
  • Acute unilateral arm swelling, heaviness, and dull ache.
  • Pitting edema, cyanosis/erythema, and dilated superficial chest wall collaterals (Urschel sign).
• Diagnosis:
  • Initial test: Compression Duplex Ultrasonography with Doppler.
  • Central/Innominate/SVC involvement: CT Venography (CTV) or MR Venography (MRV) (clavicle creates acoustic shadow on U/S).
  • Gold standard: Conventional catheter venography (reserved for planned interventions).
• Management:
  • First-line: Anticoagulation for ≥ 3 months (DOACs preferred; LMWH for malignancy/pregnancy).
  • Catheter handling:
    • Keep CVC in situ if functioning, uninfected, and clinically necessary; treat with anticoagulation.
    • Remove CVC only if: Infected (CRBSI/sepsis), malfunctioning, no longer needed, or failing AC therapy.
  • Thrombolysis (CDT): Indicated for limb-threatening ischemia (phlegmasia cerulea dolens) or acute Paget-Schroetter syndrome (< 14 days).
  • Surgical decompression: First rib resection/scalenectomy (elective, for Paget-Schroetter after thrombolysis/AC to prevent recurrence).
• Complications:
  • Pulmonary embolism (5–10% incidence).
  • Post-thrombotic syndrome (chronic pain/edema).
  • Loss of central venous access.

Management

• First-line (Hemodynamically Stable, No Contraindications):
  • DOACs (Apixaban, Rivaroxaban): First-line over Warfarin/LMWH (immediate onset, no routine coagulation monitoring, lower intracranial bleed risk). c
  • LMWH (Enoxaparin) or Fondaparinux bridged to Warfarin:
    • Overlap for $\ge 5$ days and until INR is therapeutic ($2.0–3.0$) for $\ge 24$ hours.
• Special Populations:
  • Severe Renal Impairment (CrCl < 30 mL/min): UFH bridged to Warfarin (DOACs and LMWH are renally cleared).
  • Pregnancy: LMWH throughout pregnancy and $\ge 6$ weeks postpartum (Warfarin and DOACs contraindicated).
  • Active Malignancy: DOACs (Apixaban, Rivaroxaban) or LMWH monotherapy (avoid DOACs in GI/GU luminal malignancies due to bleeding risk).
• Duration of Anticoagulation (AC):
  • Provoked DVT (transient risk factor: surgery, trauma, OCP): 3 months.
  • Unprovoked DVT / Recurrent DVT: $\ge 3–6$ months, followed by indefinite AC if bleeding risk is low.
  • Active Malignancy: Continue AC indefinitely or until cancer resolves/chemotherapy concludes.
• Second-line / Specific Interventions:
  • Inferior Vena Cava (IVC) Filter:
    • Indications: Absolute contraindication to AC (e.g., active major bleeding, recent hemorrhagic stroke) OR recurrent PE/DVT despite therapeutic AC. c
    • Must retrieve filter once AC contraindication resolves. Although IVC filters protect against PE (relative risk ~0.5), they increase the long-term risk of recurrent DVT (relative risk ~2).
  • Catheter-Directed Thrombolysis (CDT) / Thrombectomy:
    • Indication: Phlegmasia cerulea dolens (limb-threatening ischemia) or extensive proximal clot failing AC.