Deep Vein thrombosis

Question 1

Define Deep vein thrombosis

Answer 1

Development of a blood clot in a major deep vein in the leg, thigh, pelvis, or abdomen, resulting in impaired venous blood flow.

Question 2

Aetiology of deep vein thrombosis

Answer 2

Virchow’s triad: Vessel injury, venous stasis, and activation of the clotting system

Thrombophilia
- ProteinC/S/AT-III deficiency
- Factor V Leiden
- Prothrombin mutation G20210A
- Anti-phospholipid syndrome

Question 3

Risk factors for deep vein thrombosis

Answer 3

Increasing age
Pregnancy
Oestrogen products e.g. COCP, HRT
Trauma
Surgery, esp. orthopaedic
Previous DVT
Immobility: recent hospitalisation, long-haul flights
Active malignancy
Obesity

Question 4

Epidemiology of DVT

Answer 4

Relatively common, yearly incidence of 1 in every 100 adults
2/3 of all cases of VTE is DVT, 1/3 PE
300,00 deaths per year arise due to VTE (mostly PE)
Incidence increases with age
Population incidence is increasing as it ages

Question 5

Symptoms of DVT

Answer 5

Calf swelling
Tenderness (along deep venous system)
Mild fever

Question 6

Signs of DVT on examination

Answer 6

Hot, swollen, red, tender calf
- Asymmetric oedema
- Prominent superficial veins
- Calf warmth and Erythema
- Difference of calf circumference >3cm → DVT likely (measured 10cm below the tibial tuberosity + 10-15 above upper edge of patella)
Localised pain along the deep venous system from groin to adductor and popliteal fossa
- Homan’s sign: tenderness with dorsiflexion of the foot
- Pratt’s sign: calf pain on palpation

Question 7

Investigations for DVT

Answer 7

Calculate 2 level Well’s score
≥2
<4h → proximal vein US
→ +ve → start treatment
→ -ve → stop anti-coagulation → D-dimer
→ → D-dimer +ve → repeat US 1 week later

> 4h → D-dimer + start DOAC → US within 24h

<2
<4h → D-dimer + interim DOAC
→ +ve → proximal vein US (if -ve → rescan in 1 week)
→ -ve → stop DOAC, consider other diagnosis

Question 8

Management for Deep vein thrombosis

Answer 8

DOAC: dabigatran, rivvaroxaban, apixaban, edoxaban
+ warfarin
→ renal impairment/cancer/pregnancy → LMWH/unfractionated heparin + warfarin

Continue anti-coagulation:
Provoked: 3 months
Unprovoked: 6 months

Conservative: TED stockings/pneumatic compression | encourage exercise

Active bleed → IVC filter

Question 9

How are DOACs excreted and how can they be reversed

Answer 9

Excretion: DabigatRENAL, LIVERoxaban, AbPOOxaban
Dabigatran is the only reversible DOAC (with idarucizumab)

Question 10

Complications of DVT

Answer 10

Pulmonary embolism
Post-phlebitic limb (chronic venous insufficiency)

Heparin-induced thrombocytopenia (stop and start argatroban/fondaparinux)
Bleeding
Heparin resistance
Heparin → osteoporosis

Question 11

Prognosis for deep vein thrombosis

Answer 11

Most patients do not get VTE if on thromboprophylaxis.
Inadequate prophylaxis may lead to VTE
When a patient dues from DVT, it is usually from PE or from major haemorrhage as a complication of the anticoagulation.
30% of patients develop recurrent VTE between 6 months and 5 years after the initial event (off anticoagulants)