Venous thromboembolism (VTE)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Venous thromboembolism (VTE) refers to the formation of a blood clot within a vein, which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). It can lead to significant morbidity and mortality if untreated.

Aetiology

  • Deep vein thrombosis (DVT): clot formation in the deep veins, commonly in the lower limbs.
  • Pulmonary embolism (PE): occurs when a thrombus dislodges and travels to the pulmonary arteries.
  • Virchow’s triad: stasis, endothelial injury, and hypercoagulability contribute to clot formation.

Pathophysiology

  • Venous stasis, endothelial injury, or hypercoagulability triggers thrombus formation.
  • If the clot remains localised, it leads to DVT symptoms.
  • If embolisation occurs, the clot lodges in the pulmonary vasculature, causing PE.
  • Large PE can obstruct pulmonary circulation, leading to right heart strain and haemodynamic instability.

Risk Factors

  • Immobility (hospitalisation, long-haul flights).
  • Recent surgery or trauma.
  • Active malignancy.
  • Pregnancy and postpartum period.
  • Use of hormonal contraceptives or hormone replacement therapy.
  • Thrombophilia (e.g., Factor V Leiden, antiphospholipid syndrome).

Signs and Symptoms

  • DVT: unilateral leg swelling, pain, erythema, warmth.
  • PE: sudden onset dyspnoea, pleuritic chest pain, tachycardia, haemoptysis.
  • Hypoxia and hypotension in massive PE.

Investigations

  • D-dimer: elevated in VTE but non-specific.
  • Compression ultrasound: diagnostic for DVT.
  • CT pulmonary angiography (CTPA): gold standard for PE diagnosis.
  • ECG: may show S1Q3T3 pattern in PE.
  • ABG: may reveal hypoxia or respiratory alkalosis.

Management

1. Immediate Management:

  • Oxygen therapy if hypoxic.
  • Anticoagulation initiation (LMWH or DOACs such as rivaroxaban/apixaban).
  • Haemodynamically unstable PE requires thrombolysis (alteplase).

2. Long-Term Management:

  • Continue anticoagulation for at least 3 months (longer if unprovoked or recurrent VTE).
  • Compression stockings for post-thrombotic syndrome prevention.

3. Referral:

  • Haematology: for thrombophilia screening in unprovoked or recurrent VTE.
  • Respiratory: if chronic thromboembolic pulmonary hypertension suspected.
HaematologymypanotesVenous thromboembolism (VTE)