2 Indications and current treatments
2.1 Deep vein thrombosis (DVT) occurs most commonly in the deep veins of the legs. Signs and symptoms include pain, swelling, tenderness and colour change, but some DVTs cause no symptoms. Risk factors for DVT include surgery, immobility (caused by acute illness such as stroke), malignancy, acquired or inherited hypercoagulable states, pregnancy and dehydration.
2.2 DVT is associated with the risk of potentially life‑threatening pulmonary embolism (PE) and in the longer term with post‑thrombotic syndrome caused by chronic venous insufficiency, which is associated with pain, swelling, and sometimes chronic leg ulcers.
2.3 A DVT is normally treated with unfractionated or low molecular weight heparin, followed by oral anticoagulants (typically warfarin). The newer factor X inhibitors may be used without preliminary heparin. Extensive DVT is sometimes treated by systemic thrombolysis or by endovascular interventions such as catheter‑directed thrombolysis and percutaneous mechanical thrombectomy. Thrombolysis is associated with a risk of haemorrhagic complications including stroke. Surgical thrombectomy is an option in patients with DVT that is refractory to thrombolytic therapy, or for whom thrombolysis is contraindicated, but it is rarely used.