Deep vein thrombosis is defined as the formation of a thrombus within a deep vein.
Presentation
The following classical signs and symptoms appear in the lower limbs of around 50% of the patients with deep vein thrombi [7] [8].
- Swelling of the leg
- Pain or tenderness which may be associated with walking or standing
- Erythema or discolored skin
- Dilated superficial veins
- Low grade fever with increased pulse
- Calf tenderness
Phlegmasia alba dolens (white leg): This condition is characterized by pain, pitting edema and blanching. There is no associated cyanosis. The condition occurs because of obliteration of the major deep venous channels with relative sparing of collateral veins. As a result, swelling occurs but there is no cyanosis.
Phlegmasia cerulea dolens (Blue leg): The condition occurs when the thrombi involve the deep veins as well as the collateral channels. Thus all the venous outflow is blocked and there is massive fluid sequestration and significant edema. The affected limb in phlegmasia cerulea dolens is extremely painful, edematous and cyanotic and may be associated with arterial insufficiency and compartment syndrome. If untreated venous gangrene ensues which may even require amputation.
Signs
- Homan’ s Test: Forcible dorsiflexion of foot results in severe pain in the calf region. It is not used commonly now.
- Moses Test: In this test, tenderness over the calf muscles is elicited on squeezing the muscle from side to side. Ideally, it should not be performed as there is risk of embolization.
Workup
The investigations that are necessary to diagnose deep vein thrombosis include:
- Duplex ultrasound: Duplex ultrasound is the test of choice to diagnose deep vein thrombosis as it is non-invasive, hazard-free and reliable.
- Contrast venography: Radio-opaque dye is injected into dorsal venous arch and an x-ray radiograph is taken. A clot if present appears as a filling defect.
- Blood tests: People with severe deep vein thrombosis have an elevated level of a clot-dissolving substance called D-dimer. Many inherited and acquired causes of hypercoagulability such as anti-thrombin III, protein C or protein S deficiency can also be detected by blood test.
- CT scan or MRI scans: These investigations are helpful as they can provide visual images of veins and may show a clot.
Treatment
The treatment options for deep vein thrombosis include the following.
- Elevation of limb: This is essential to regulate unidirectional flow of blood.
- Compression stockings: These help prevent the swelling associated with deep vein thrombosis. These are worn on the legs from feet to above the level of knees.
- Filters: A filter may be inserted into a large vein (such as the vena cava) that prevents clots that break loose from lodging into lungs [9].
- Blood thinners: The anticoagulants used to treat deep vein thrombosis include heparin and warfarin. Intravenous heparin is given according to weight of patient. Generally 10,000 units intravenous bolus with continuous infusion of 30,000 to 45,000 units per day is given. Warfarin is started 2-3 days before withdrawal of heparin because of its slow onset of action.
- Venous thrombectomy: Thrombus can be removed by opening the femoral vein via incision in the groin.
- Thrombolysis: This is a modern technique. Catheter is passed in the vein and streptokinase is infused locally to cause thrombolysis [10].
Prognosis
Many individuals who have a first episode of deep vein thrombosis will have a recurrent event. The risk of recurrence may be reduced by the use of compression stockings. Untreated cases of deep vein thrombosis can lead to pulmonary embolism which is one significant causes of death in these patients [6].
Etiology
The various factors responsible for deep vein thrombosis include the following:
- Trauma: This leads to the injury to vessel wall. A broken hip or leg and subsequent surgeries are the common causes for the development of venous thrombi [1].
- Hormones: Oral contraceptive pills and the current use of hormone therapy especially in postmenopausal women can contribute to this condition.
- Road traffic accidents: Accidents causing trauma can also reduce blood flow to any part of the body leading to thrombosis.
- Operations: Surgical procedures such as cholecystectomy and splenectomy can be a common cause of deep vein thrombosis.
- Malignancy: People with cancer or a malignant mass have an increased risk for the development of deep vein thrombosis.
- Blood disorders: Conditions such as thrombophilia that cause the blood to clot more easily than normal can increase the risk [2] [3].
- Obesity: Obesity, especially in older people over 60 years of age, is closely linked with the development of deep vein thrombosis.
- Stroke: Conditions like stroke and heart failure increase the risk of deep vein thrombosis.
- Immobilization: Any illness or injury that causes immobility predisposes the person to the formation of deep vein thrombi [4]. Long travel is often a risk factor [5].
- Male gender: Deep vein thrombosis is more common in men as compared to women.
Epidemiology
Deep vein thrombosis is more common in men than in women. The incidence is four times higher in the elderly over the age of 60 years.
In the United States, it is estimated that about 1 in 1,000 people have a deep vein thrombosis each year. On average, one in every 20 people develops deep vein thrombosis at least once in the course of his or her lifetime.
Pathophysiology
The pathophysiology of thrombus formation in deep vein thrombosis is explained by Virchow’s triad.
- Endothelial injury: Endothelial damage in the blood vessel that may be intrinsic or due to external trauma leads to rupture of the vessel wall. This reduces the blood flow to a particular part, which activates certain biochemical pathways, leading to thrombus formation. The factors causing endothelial injury include hypertension, endotoxin, trauma, smoking and antiphospholipid syndrome.
- Venous stasis: Certain conditions like cardiac arrhythmias, aneurysms and prolonged period of rest after surgery lead to stasis or turbulence of blood flow. Lack of motion can cause sluggish blood flow causing thrombus formation.
- Blood hypercoagulability: Blood may become thick and clot easily in certain inherited conditions like antithrombin III deficiency and protein C or S deficiency. Hormone therapy and birth control pills also can increase the risk of clot formation.
Prevention
Deep vein thrombosis can be prevented by ensuring of a healthy life style, proper diet and regular exercise. Long periods of immobility must be avoided after major surgical procedures or on long travels.
People who are overweight must reduce their weight to prevent the risk of deep vein thrombosis. Regular checking of blood pressure with plenty of fluids intake and avoid smoking may also help prevent the risk of deep vein thrombosis.
Summary
Deep vein thrombosis is a condition in which there is formation of blood clots in the deep veins. These blood clots are known as thrombi and they can form in veins anywhere in the body; however, the large veins in legs and thighs are most frequently involved.
The condition is characterized by swelling, pain and tenderness, often in the legs. Risk factors for the formation of thrombi include immobility, hormone therapy and pregnancy. Deep vein thrombosis are most common in the elderly over 60 years of age; however, no age is immune.
A thrombus in a deep vein can break off and travel to lungs through bloodstream, leading to pulmonary embolism.
Patient Information
Deep vein thrombosis is a blood clot that usually forms in the deep veins of the lower leg and thigh. The patients usually develop swelling and pain of the leg and changes in the color of the overlying skin. Sitting for long periods when travelling can increase the risk of deep vein thrombosis. With proper medications and regular exercise, the disease has a good prognosis.
References
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- Dahlback B. Inherited thrombophilia: resistance to activated protein C as a pathogenic factor of venous thromboembolism. Blood. Feb 1 1995;85(3):607-614.
- Jensen R, Ens GE. Resistance to activated protein C: a major cause of inherited thrombophilia. Clinical laboratory science : journal of the American Society for Medical Technology. Jul-Aug 1997;10(4):219-222.
- Slipman CW, Lipetz JS, Jackson HB, Vresilovic EJ. Deep venous thrombosis and pulmonary embolism as a complication of bed rest for low back pain. Archives of physical medicine and rehabilitation. Jan 2000;81(1):127-129.
- Arfvidsson B. Risk factors for venous thromboembolism following prolonged air travel: a prospective study. Cardiovascular surgery. Apr 2001;9(2):158-159.
- Tapson VF. Acute pulmonary embolism. The New England journal of medicine. Mar 6 2008;358(10):1037-1052.
- McLachlin J, Richards T, Paterson JC. An evaluation of clinical signs in the diagnosis of venous thrombosis. Archives of surgery. Nov 1962;85:738-744.
- Haeger K. Problems of acute deep venous thrombosis. I. The interpretation of signs and symptoms. Angiology. Apr 1969;20(4):219-223.
- Jaff MR, McMurtry MS, Archer SL, et al. Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association. Circulation. Apr 26 2011;123(16):1788-1830.
- Todd JL, Tapson VF. Thrombolytic therapy for acute pulmonary embolism: a critical appraisal. Chest. May 2009;135(5):1321-1329.