Blood Clots: Deep Vein Thrombosis
Basics
Deep vein thrombosis (DVT) is a blood clot in a deep vein of the body, usually in the thigh or leg. The deep veins are the main blood vessels returning blood from the tissues of the body back to the heart (such as the femoral vein). Figure 01.
Figure 01. Deep vein thrombosis
If a blood clot (thrombus) forms in a deep vein, it can block the flow of blood, which prevents the tissues from draining properly. This causing excess fluid accumulation, swelling, warmth, and discomfort in the leg.
A blood clot in a deep vein may also break off and travel back to the heart and into the lungs, causing a condition called pulmonary embolism. Pulmonary embolism can be minor and go unnoticed, or it can be significant and cause difficulty breathing, sharp chest pain, and even death. Less commonly, the clots can also travel through the heart back to the rest of the body, including the brain. This is called a paradoxic embolism. A blood clot that travels this way to the brain can be a cause of stroke.
DVT is different from a clot in a vein close to the surface of the body, such as a vein near the skin or in the calf. These superficial clots, while often uncomfortable, are usually not dangerous and are not treated in the same way as DVT.
DVT is treated with medications that lower the chances of new clots forming and allow the body to dissolve the clot over time.
Causes
Blood clots in the veins of the legs cause DVT.
When the bloodflow in the arteries and veins is blocked, a blood clot (thrombus) may form. A thrombus that forms in the larger veins of the legs may break off and travel through the bloodstream to become an embolus.
People who have conditions that cause blood to flow slowly in the veins, or who have a higher chance of blood clots, are at greatest risk of developing DVT.
The condition tends to occur in people who:
Symptoms
Symptoms of DVT usually occur in one leg. Pain, warmth, and swelling are just some of the symptoms. Other symptoms include tenderness, discomfort, changes in skin color (e.g. bluish skin discoloration or redness), and joint pain.
The pain often is below the knee--often in the calf--and may increase during standing or walking. However, many people with DVT may not show symptoms.
If pulmonary embolism occurs, symptoms include shortness of breath and sharp chest pain that is worse with taking a deep breath.
Risk Factors
Lack of exercise or movement may predispose people to DVT.
People who do not move for prolonged periods of time, such as during a long plane flight or a cross-country drive, are at risk for DVT. It is important to change positions often; stand up and walk around at least once every one to two hours. You can also flex your feet and leg muscles while sitting.
Most often, DVT forms when a person is hospitalized and at bedrest, such as after a hip operation or for another major illness or surgery. Ten percent to thirty percent of medical and surgical intensive care unit patients have DVT within the first week of admission. As a result, patients who are subject to bed rest should follow an exercise routine that uses active and passive motion of the arms and legs.
If you cannot exercise your legs, your doctor may recommend special treatments to lower the risk of DVT, such as compression stockings or medications.
A traumatic injury or surgery--especially to the legs or hips--may predispose people to DVT.
This risk can occur as a result of trauma to the blood vessels, or as a result of the long period of immobilization required after a major surgery or an injury such as a fracture.
Pregnancy and certain hormonal medications may predispose women to DVT.
During pregnancy and for three months following childbirth, women are at increased risk for DVT. Medications such as estrogen and birth control pills may cause women to be at increased risk of DVT, especially in women who are also smokers.
Obesity may predispose people to DVT Figure 02
Figure 02. BMI calculator
People who are obese may have other conditions that increase the risk of DVT. In addition, a large number of obese people are less active, which may also increase the risk of blood clots.
Certain inherited conditions may predispose people to DVT.
In order for blood clots to form and dissolve, certain factors in the blood are necessary. Some inherited conditions cause defects in these factors; individuals with these defects are more likely to form blood clots. The most common defect is resistance to a protein called activated protein C (factor V Leiden); people with this defect are more likely to form a DVT.
People with certain cancers such as lung or breast cancer may be at increased risk for developing DVT.
Elderly people may be predisposed to DVT.
As the condition of the heart and veins changes with age, DVT becomes more common. The blood vessels become thicker, stiffer, and less elastic. Circulation may slow and blood clots may result.
Diagnosis
Deep vein thrombosis (DVT) is a blood clot in a deep vein of the body, usually in the thigh or leg. The deep veins are the main blood vessels returning blood from the tissues of the body back to the heart (such as the femoral vein). Figure 01.
Figure 01. Deep vein thrombosis
If a blood clot (thrombus) forms in a deep vein, it can block the flow of blood, which prevents the tissues from draining properly. This causing excess fluid accumulation, swelling, warmth, and discomfort in the leg.
A blood clot in a deep vein may also break off and travel back to the heart and into the lungs, causing a condition called pulmonary embolism. Pulmonary embolism can be minor and go unnoticed, or it can be significant and cause difficulty breathing, sharp chest pain, and even death. Less commonly, the clots can also travel through the heart back to the rest of the body, including the brain. This is called a paradoxic embolism. A blood clot that travels this way to the brain can be a cause of stroke.
DVT is different from a clot in a vein close to the surface of the body, such as a vein near the skin or in the calf. These superficial clots, while often uncomfortable, are usually not dangerous and are not treated in the same way as DVT.
DVT is treated with medications that lower the chances of new clots forming and allow the body to dissolve the clot over time.
Blood clots in the veins of the legs cause DVT.
When the bloodflow in the arteries and veins is blocked, a blood clot (thrombus) may form. A thrombus that forms in the larger veins of the legs may break off and travel through the bloodstream to become an embolus.
People who have conditions that cause blood to flow slowly in the veins, or who have a higher chance of blood clots, are at greatest risk of developing DVT.
The condition tends to occur in people who:
Symptoms of DVT usually occur in one leg. Pain, warmth, and swelling are just some of the symptoms. Other symptoms include tenderness, discomfort, changes in skin color (e.g. bluish skin discoloration or redness), and joint pain.
The pain often is below the knee--often in the calf--and may increase during standing or walking. However, many people with DVT may not show symptoms.
If pulmonary embolism occurs, symptoms include shortness of breath and sharp chest pain that is worse with taking a deep breath.
Lack of exercise or movement may predispose people to DVT.
People who do not move for prolonged periods of time, such as during a long plane flight or a cross-country drive, are at risk for DVT. It is important to change positions often; stand up and walk around at least once every one to two hours. You can also flex your feet and leg muscles while sitting.
Most often, DVT forms when a person is hospitalized and at bedrest, such as after a hip operation or for another major illness or surgery. Ten percent to thirty percent of medical and surgical intensive care unit patients have DVT within the first week of admission. As a result, patients who are subject to bed rest should follow an exercise routine that uses active and passive motion of the arms and legs.
If you cannot exercise your legs, your doctor may recommend special treatments to lower the risk of DVT, such as compression stockings or medications.
A traumatic injury or surgery--especially to the legs or hips--may predispose people to DVT.
This risk can occur as a result of trauma to the blood vessels, or as a result of the long period of immobilization required after a major surgery or an injury such as a fracture.
Pregnancy and certain hormonal medications may predispose women to DVT.
During pregnancy and for three months following childbirth, women are at increased risk for DVT. Medications such as estrogen and birth control pills may cause women to be at increased risk of DVT, especially in women who are also smokers.
Obesity may predispose people to DVT Figure 02
Figure 02. BMI calculator
People who are obese may have other conditions that increase the risk of DVT. In addition, a large number of obese people are less active, which may also increase the risk of blood clots.
Certain inherited conditions may predispose people to DVT.
In order for blood clots to form and dissolve, certain factors in the blood are necessary. Some inherited conditions cause defects in these factors; individuals with these defects are more likely to form blood clots. The most common defect is resistance to a protein called activated protein C (factor V Leiden); people with this defect are more likely to form a DVT.
People with certain cancers such as lung or breast cancer may be at increased risk for developing DVT.
Elderly people may be predisposed to DVT.
As the condition of the heart and veins changes with age, DVT becomes more common. The blood vessels become thicker, stiffer, and less elastic. Circulation may slow and blood clots may result.
If you are suspected of having DVT, you may undergo several tests to evaluate your veins and the tendency of your blood to clot.
Imaging tests may locate the blood clot and confirm a diagnosis of DVT. Doctors can also analyze your blood to determine if it is likely to form clots.
Invasive tests may be used to detect DVT.
Other tests may be used to rule out other possible causes of your symptoms.
Move your legs if you sit for long periods of time.
Prolonged sitting, bed rest, and lack of movement increase the chance of blood clots forming in the deep veins of the legs. When you have to sit for long periods of time--for example, during long airline flights--move your legs, such as by flexing your ankle up and down (as though you are pressing the accelerator of a car with your foot). Repeat this exercise 20 times every one to two hours.
Walk up and down the aisle of a plane every hour or two for a few minutes. If traveling in a car, pull over at a rest stop to stretch your legs every two hours.
Increase your intake of fluids when traveling in an airplane.
People who travel in airplanes for extended periods of time have a tendency to become dehydrated. If you have a history of blood clots, dehydration may cause your blood to thicken, increasing your risk of developing DVT. To prevent dehydration, drink an eight-ounce glass of water every two hours. Avoid drinking too much alcohol and coffee when flying, as they increase dehydration.
Wear elastic compression stockings.
If you have a history of blood clots or leg swelling, elastic stockings reduce leg swelling and reduce the chance that blood clots will form in the legs. The stockings must be worn snugly in order to offer support while ensuring adequate circulation. Stockings should not be worn for more than a full day at a time. They are available over-the-counter at surgical supply stores. These elastic compression stockings work by periodically filling with air and squeezing your legs.
Small doses of aspirin may decrease surgical complications associated with the formation of blood clots and DVT. Research suggests that aspirin may reduce the risk of blood clot formation in patients who have surgery for a hip fracture. Compared to other medications used to prevent blood clot formation, aspirin is easy to take and inexpensive. Some people cannot tolerate aspirin, so you should speak with your doctor before taking it regularly.
Prevention and Screening
Move your legs if you sit for long periods of time.
Prolonged sitting, bed rest, and lack of movement increase the chance of blood clots forming in the deep veins of the legs. When you have to sit for long periods of time--for example, during long airline flights--move your legs, such as by flexing your ankle up and down (as though you are pressing the accelerator of a car with your foot). Repeat this exercise 20 times every one to two hours.
Walk up and down the aisle of a plane every hour or two for a few minutes. If traveling in a car, pull over at a rest stop to stretch your legs every two hours.
Increase your intake of fluids when traveling in an airplane.
People who travel in airplanes for extended periods of time have a tendency to become dehydrated. If you have a history of blood clots, dehydration may cause your blood to thicken, increasing your risk of developing DVT. To prevent dehydration, drink an eight-ounce glass of water every two hours. Avoid drinking too much alcohol and coffee when flying, as they increase dehydration.
Wear elastic compression stockings.
If you have a history of blood clots or leg swelling, elastic stockings reduce leg swelling and reduce the chance that blood clots will form in the legs. The stockings must be worn snugly in order to offer support while ensuring adequate circulation. Stockings should not be worn for more than a full day at a time. They are available over-the-counter at surgical supply stores. These elastic compression stockings work by periodically filling with air and squeezing your legs.
Small doses of aspirin may decrease surgical complications associated with the formation of blood clots and DVT. Research suggests that aspirin may reduce the risk of blood clot formation in patients who have surgery for a hip fracture. Compared to other medications used to prevent blood clot formation, aspirin is easy to take and inexpensive. Some people cannot tolerate aspirin, so you should speak with your doctor before taking it regularly.
Treatment
If you suspect you may have DVT , seek the attention of a doctor immediately. Go to an emergency room if you have chest pain and shortness of breath, a sign that the blood clot has traveled from your leg to your lungs, called a pulmonary embolism.
If you have DVT, you may be hospitalized for one to five days for treatment with both intravenous and oral medication. Your doctor will decide which medicine is the best for you.
You will probably need to make medication for at least 6 months following your hospital discharge. Some people take medication for the rest of their lives to prevent another DVT. Long-term anticoagulation therapy requires close monitoring of the levels of medication in your blood. You will need to follow up closely with your doctor or with another healthcare provider to make sure you are taking the correct dose of medication.
Your doctor may limit your activities until your symptoms are relieved.
When DVT is first diagnosed, your doctor may limit your activities until your symptoms are relieved, which may reduce swelling and prevent the clot from breaking off and traveling through the bloodstream.
Avoid prolonged sitting or standing in one position after being treated for DVT.
To reduce the risk of further episodes of DVT, avoid prolonged sitting or standing in one position. When you find yourself in an inactive or confined situation, flex your legs and feet periodically. Support stockings may also lower the risk of future DVT.
Apply heat to the affected area to help relieve the pain.
Your doctor is the best source of information on the drug treatment choices available to you.
Clot-trapping filters can help in some circumstances.
If you have DVT but cannot take anticoagulant medications, or if DVT occurs while you are already taking anticoagulants, a special, fine-meshed screen filter may be placed in the main vein that connects the lower body to the heart (inferior vena cava) to reduce the chances of a DVT going to the heart and lungs. This filter acts as a trap for blood clots that break off from the lower body, so that they cannot enter the heart or lungs. The filter does not reduce the chance of a DVT forming, however, so if you are able to take anticoagulant medications, you should continue to do so after the surgery.
If you are pregnant and have DVT, you will be treated with medication that is safe if pregnancy.
If you are a woman who is pregnant or has had a baby within the last few months, you may be predisposed to DVT.
If you have symptoms suggestive of DVT while pregnant or in the first few months after childbirth, contact your doctor immediately.
Do not smoke if you are taking birth control pills or estrogen.
If you are a woman who is taking birth control pills or estrogen hormone replacement therapy, you should not smoke cigarettes, as smoking will significantly increase your risk of DVT.
If you have previously had DVT, you are at increased risk of having another DVT in the future.
To reduce the chances of repeat DVT, avoid prolonged bed rest, sitting, or standing. If you find yourself in an inactive or confined situation, flex your legs and feet periodically. Compression support stockings (see above) may also lower the risk of further DVT. Your doctor may also decide to put you on anticoagulant medication such as warfarin indefinitely to lower your risk of future DVT.
In most cases, DVT can be treated with medications to prevent more clot from forming, allowing your body to dissolve the clot.
Of those people treated with anticoagulant medications for six months, about 5% to 10% have a repeat DVT after treatment. Although the best duration of anticoagulant treatment is unknown, in most cases your treatment will continue for at least three to six months for a first DVT, and perhaps longer if this is a repeat DVT.
Although most people recover after DVT, some tissue damage to the veins may remain.
After an episode of DVT, the affected veins may be damaged, even after the clot is dissolved. This may cause long-term swelling in that leg, and may increase the risk of future DVT. Compression support stockings usually help in these cases.
Age and prior medical history of blood clots are risk factors for recurrent DVT.
The majority of people with DVT are over the age of 60. As people age, the condition of their heart and blood vessels changes, which may predispose them to DVT.
Patients receiving treatment for DVT must be monitored closely by a physician.
People with DVT who are being treated with medication need regular monitoring of their blood levels of these medications. Monitoring is usually done more frequently at first, such as once or twice per week, and less frequently as medication levels and dosing stabilize.
Report any medication side effects or complications to your physician promptly.
Patients receiving anticoagulation medication are at higher risk of bleeding. If you are taking these medications and you experience significant bleeding that will not stop, go immediately to the emergency room.
Report increased leg swelling or discomfort, or new symptoms such as shortness of breath or chest pain to your physician promptly.
While treatment with medications is usually effective, in some cases the DVT may still get worse, or a pulmonary embolism may still occur. If your leg swelling or other leg symptoms are worsening, contact your doctor. If you have new symptoms such as shortness of breath or chest pain, this may represent a pulmonary embolus. A pulmonary embolus is a medical emergency, and you should contact your doctor immediately or go to an emergency room.