What is Deep Vein Thrombosis?
Deep vein thrombosis is a health condition in which clotting of blood occurs in a deep vein inside the body. It usually develops in a vein of a thigh or leg, but it can develop in other parts of the body too. DVT can cause serious disability and can result in the death of a person. But if detected early, it is treatable and can be prevented by reducing the risk factors for its development.
It is however possible to have deep vein thrombosis without any symptoms.
Common symptoms produced by DVT
- Swelling of one or both legs.
- Cramping pain in the affected leg.
- Swollen veins that are tender to touch and feel hardened on palpation.
- Increased temperature of the affected region of the skin.
- Red discoloration of the affected region and the surrounding skin.
Common risk factors for DVT
Although deep vein thrombosis can develop in anybody regardless of age, gender, and race, certain factors increase the likelihood of developing deep vein thrombosis. These factors do not cause deep vein thrombosis and it is possible to have one or two of these risk factors and not develop DVT. Sometimes DVT develops in absence of any of the following risk factors.
- If the person is over 60.
- If the person has a smoking history or is a current smoker.
- If the person is overweight.
- If there is a family history of deep vein thrombosis.
- If there is a previous history of deep vein thrombosis.
- If there is a history of varicose veins.
- If the person has an inherited tendency of increased chances of developing blood clots.
- If a person has a chronic illness like cancer, heart failure, lung disease, and inflammatory bowel disease.
Certain other situations can also increase the chances of one developing deep vein thrombosis. These are:
- Prolonged stay in hospital particularly immobility for a long time.
- Prolonged bed rest.
- Recent surgery.
- Long travel.
- If a woman has had a baby in the last 6 weeks.
How is deep vein thrombosis diagnosed?
Different tests can be used to diagnose deep vein thrombosis. These tests are described below:
- Duplex ultrasonography: It is the standard test for diagnosing DVT and it is also the first test used. This test detects blood clots in deep veins by using sound waves to estimate the direction of blood flow in the veins. It is a very useful test to diagnose blood clots in veins above the knee but its ability to detect blood clots below the knee is not as good.
- D-dimer test: this test measures a degradation product that is released in the bloodstream when a clot is broken down. When a clot is formed in a vein, a process ensues simultaneously that involves the breakdown of that clot. During that breakdown, many substances are released and dimer measures one of those substances. If the d-dimer is negative, it is very unlikely that the person has had blood clots or currently has blood clots in his/her veins.
- Contrast venography: in this test, a contrast material (that illuminates the veins) is injected into the veins and then, an x-ray is taken of the relevant area of the body, and veins are visualized on x-ray and the presence or absence of blood clots in veins is established. It is the most accurate test for diagnosing deep vein thrombosis. As this test is invasive and can be painful for the patient, it has been largely replaced by duplex ultrasonography and its utility is significant in some patients only.
- Magnetic resonance imaging: MRI can also be used to diagnose deep vein thrombosis. A particular benefit of MRI is that there is no need to compress veins and it can be performed if a patient has a cast on their legs. MRI uses radio waves and magnetic fields to provide images of the body from various angles. This test can be used to visualize veins and clots in them.
Treatment options for deep vein thrombosis
Deep vein thrombosis is treated using different types of medications. Most commonly, anticoagulants are used to treat DVT.
- Anticoagulants: These drugs work by reducing the ability of blood to form clots. So, they prevent the clot to increase its size and facilitate reabsorption of clots. They also decrease the chances of the development of further clots. Anticoagulants can be injected or taken orally. Anticoagulants that are commonly injected are low molecular weight heparin, unfractionated heparin, and fondaparinux. Some anticoagulants that are taken orally are Rivaroxaban, warfarin, and dabigatran. An invariable side effect that is caused by almost all anticoagulants is bleeding. So, it is very important to monitor bleeding and clotting status while a person is taking anticoagulants.
- Thrombolytics: Thrombolytics are drugs that dissolve the clot. They have an increased risk of bleeding, so they are given only in severe cases involving some form of clotting crisis.
- Inferior vena cava filter and thrombectomy: Inferior vena cava filter is used when the clotting crisis is not responding to anticoagulants. In this, a filter is placed in the inferior vena cava which traps the coming clot from deep veins of the leg and prevents its entry into the heart, lungs, and brain. Thrombectomy means surgical removal of the blood clot. This is rarely performed.
How can deep vein thrombosis be prevented?
It can be prevented by decreasing the same risk factors which are involved in increasing the likelihood of developing DVT. Although reducing these risk factors does decrease the chances of developing deep vein thrombosis, it is very much possible to develop DVT despite the absence of these risk factors.
Following are some of the factors that play a role in the prevention of deep vein thrombosis:
- Maintaining a healthy weight by eating healthy foods and by doing regular physical activity.
- Drinking plenty of fluids to avoid dehydration.
- Avoiding staying still for longer durations.
- Avoiding smoking and heavy alcohol drinking.
Some other specific preventive strategies include:
- Starting physical activity as soon as possible after surgery.
- Using a pneumatic compression device during or after the surgery.
- Using elastic stockings to keep the blood flowing in the veins.
NHS, DVT (deep vein thrombosis), Accessed April 16, 2021, https://www.nhs.uk/conditions/deep-vein-thrombosis-dvt/
Centers for disease control and prevention, Venous thromboembolism, Accessed April 16, 2021, https://www.cdc.gov/ncbddd/dvt/index.html
Stanford Healthcare, Deep vein thrombosis, Accessed April 16, 2021, https://stanfordhealthcare.org/medical-conditions/blood-heart-circulation/deep-vein-thrombosis.html
Medicine plus, Deep vein thrombosis, Accessed April 16, 2021, https://medlineplus.gov/deepveinthrombosis.html