2 The condition, current treatments and procedure
2.1 Deep vein thrombosis (DVT) is a blood clot that develops within a deep vein, usually in the leg. It can cause pain, swelling, tenderness and red skin but sometimes there are no symptoms. Risk factors for DVT include surgery, immobility, malignancy, hypercoagulability, pregnancy and dehydration.
2.2 DVT may lead to complications because the blood flow in the leg is being affected. Chronic venous insufficiency can cause post‑thrombotic syndrome in the affected leg with pain, swelling, and sometimes chronic ulceration. Raised venous pressure can rarely cause phlegmasia cerulean dolens with oedema of the leg, cyanosis, blistering and ischemia. If the clot becomes dislodged it can travel through the veins to the lungs and cause a pulmonary embolus, which is potentially life‑threatening.
2.3 A DVT is usually treated with anticoagulation. Extensive DVT is sometimes treated with systemic thrombolysis, or by endovascular interventions such as catheter‑directed thrombolysis. Thrombolysis is associated with a risk of haemorrhagic complications including stroke. Surgical thrombectomy is an option when a DVT is refractory to thrombolytic therapy, or in people for whom thrombolysis is contraindicated, but it is rarely used.
2.4 Percutaneous mechanical thrombectomy for acute DVT of the leg is usually done together with direct infusion of a thrombolytic drug into the thrombus. However, it can be done by itself if thrombolytic drugs are contraindicated. It can also be done before thrombolysis to reduce the size of the clot, or after thrombolysis if the thrombus persists.
2.5 The procedure is done using local anaesthesia. Imaging is used to determine the appropriate venous access, which is usually the popliteal or femoral vein. A catheter is advanced through the vein into the thrombus using fluoroscopic guidance. There are a range of mechanical thrombectomy devices that use different principles. The objective is mechanical disruption and aspiration of the thrombus. A temporary inferior vena cava filter may be used during the procedure to reduce the risk of pulmonary embolism from a displaced clot.
2.6 Anticoagulant drugs are usually taken for at least 3 months after the procedure and sometimes longer if clinically indicated, to prevent recurrence. Early ambulation and use of compression stockings are advised.
2.7 Adjuvant angioplasty or stenting of the vein may be needed if thrombus removal reveals an anatomical lesion that contributed to the formation of the DVT or that increases the risk of recurrence.