General Information
- Venous Thromboembolism is a common and potentially fatal condition
- “Deep Vein Thrombosis” is the diagnosis of having a blood clot develop in your venous circulation
- Blood clots develop due to stagnation of blood and hypercoagulable states
- Blood clots can mobilise (become emboli) from the deep veins and travel through the right side of the heart and into the lungs (becoming pulmonary embolisms)
- If the patient has a hole in their heart (i.e. a ventricular septal defect) the blood clot can pass through to the left side of the heart and get sent to the systemic circulation – typically causing a large stroke (this is a common exam question)
N.B. See Respiratory Section for Pulmonary Embolism notes
Risk factors
- Immobility
- Recent surgery
- Long haul flights
- Pregnancy
- Hormone therapy with oestrogen (combined oral contraceptive pill and hormone replacement therapy for postmenopausal women)
- Malignancy
- Polycythaemia
- Systemic lupus erythematosus
Wells Score
- Predicts risk of DVT and pulmonary embolism
- Use online calculators to calculate score
Presentation
- Unilateral
- Calf/leg swelling (measure circumference of the calf 10cm below the tibial tuberosity, >3cm difference is significant)
- Dilated superficial veins
- Tenderness to the calf (particularly over the site of the deep veins)
- Oedema
- Colour changes to the leg
N.B. Always ask questions and examine with the suspicion of a potential P.E. as well
Diagnosis
- D-Dimer is sensitive (95%), but not specific (it will go up if there is a DVT, but if it is raised, it could be due to other factors like a pneumonia, DVT, malignancy, rheumatoid arthritis etc)
- If a D-Dimer is positive and Doppler negative, repeat the doppler after 6-8 days
- Confirm the diagnosis with a ultrasound Doppler of the leg
- Patients should have this within 4 hours or receive LMWH whilst waiting
- Both should be negative to exclude a DVT in patients with a high Wells score
Management
- Analgesia.
- Treatment dose LMWH (i.e. enoxaparin 1.5mg/kg) for >5 days (or until INR 2-3 if on warfarin).
- Long term anticoaguation with a NOAC (first line), warfarin (second line) or LMWH(third line)
- Target INR for warfarin is 2-3.
- NOAC options include apixaban, dabigatran and rivaroxaban.
- Continue anticoagulation for:
- 3 months if obvious reversible cause
- Indefinitely if cause unclear / underlying irreversible cause (e.g. cancer) / recurrent VTE
Prevention
- Every admission to hospital should be assessed for venous thromboembolism (VTE) risk.
- If at increased risk of VTE they should receive prophylaxis
- If no contraindications, this should be 40mg of enoxaparin
- If eGFR <30, 20mg enoxaparin
- If risk of bleeding, then use compression stockings