Deep Vein Thrombosis or DVT is a fairly common condition in which a blood clot develops in a deep vein. DVT usually affects the deep veins of the leg. In most people, DVT occurs in the large vein that runs through the thigh and calf muscle. These blood clots that occur in veins are also called venous thrombosis.
Many people have no symptoms of DVT and do not realise anything is wrong until they develop complications. DVT can also cause swelling and pain of the leg. Deep Vein Thrombosis is a serious condition that can lead to life-threatening complications like pulmonary embolism in which the clot breaks off and travels to the lungs.
Causes of Deep Vein Thrombosis
About 1 in 1,000 people in the UK develop DVT every year, but certain groups are at a much higher risk of developing the condition. One of the biggest risk factors is age. The following are the most common causes and risk factors of Deep Vein Thrombosis.
The risk of developing Deep Vein Thrombosis increases with age. DVT usually occurs in people over 40 but the risk increases further past the age of 60 — especially for people who have another health condition that increases the risk like mobility issues, heart disease, or obesity.
If you are admitted to hospital, you may be at an increased risk of Deep Vein Thrombosis. DVT often happens when you are inactive, after an illness or injury, or after surgery.
The type of treatment you receive affects your risk of DVT. The following treatments in hospital may put you at risk of a blood clot:
- You cannot walk or are confined to a bed for 3 or more days
- You are having surgery that takes more than 90 minutes, or a procedure on your abdomen, hip, or leg that takes 60 minutes or more.
- You are having surgery for an abdominal or inflammatory condition.
Inactivity after a serious injury or surgery also increases the risk.
Damage to Blood Vessels
Chemotherapy, varicose veins, vasculitis (an inflammatory condition of the blood vessels) and other conditions may cause damage to the walls of blood vessels. This can cause the vessel to become blocked or narrowed which increases the likelihood of a clot developing. Some blood clots also develop due to an injury or surgery that damages a blood vessel in the leg.
Blood clots are naturally more common during pregnancy and the postpartum period as it’s the body’s way to reduce blood loss during delivery. Some pregnant women also experience reduced blood flow to the legs in the third trimester as blood vessels in the pelvis are compressed. Women who are pregnant are up to 10x more likely to develop a blood clot than women who aren’t pregnant.
The risk of blood clots during pregnancy increases for women who:
- Have severe varicose veins
- Recently had a C-section
- Have been immobile or on best rest for an extended period of time
- Have a BMI of 30 or more
- Are Over 35 years old
Hormone Replacement & Oral Contraceptives
Hormone replacement therapy (HRT) and the combined contraceptive both contain oestrogen which makes blood clot more easily. These hormone treatments won’t dramatically increase the risk of DVT, however.
Inactivity causes blood to collect in the lower legs. This is normal and typically no cause for concern as blood flow increases and improves when you get up and move. Inactivity for a long period of time, however, can significantly slow blood flow and make it easier for a clot to form.
People who have been inactive due to an injury or surgery are at an increased risk of DVT. Extended sitting, especially in a cramped aeroplane, can also increase the risk for DVT. It’s believed that flights that last more than eight hours pose the greatest threat for travellers at risk of DVT.
The best way to combat this risk is by moving as much as possible. On a flight, get up and move every 30 to 60 minutes. After surgery, follow the physician’s advice and get up for even the shortest walks as soon as you are able.
Genetics & Health Conditions
There are a number of health and genetic conditions that make the blood clot more easily than normal. Common conditions linked to Deep Vein Thrombosis include:
- Cancer. Cancer can damage tissue in the body which causes swelling and may trigger blood clots. Radiotherapy and chemotherapy also increase the risk of a deep vein clot.
- Lung disease and heart disease.
- Certain inflammatory diseases like rheumatoid arthritis (RA)
- Antiphospholipid syndrome, an autoimmune disorder that can cause blood clots
- Thrombophilia, a genetic disorder that makes the blood more likely to clot
Other Common Causes of DVT
There are other risk factors of DVT that include:
- Being overweight or obese
Treatment of Deep Vein Thrombosis
The standard treatment for Deep Vein Thrombosis involves anticoagulant medication to prevent an existing clot from getting larger and reduce the blood’s clotting ability. Anticoagulant medications won’t dissolve or break up a clot, but they will stop it from worsening as the body naturally absorbs the clot over a period of time. They work by changing proteins in the blood that stops clots from forming easily.
The two most common anticoagulants to treat DVT are:
- Heparin which is often prescribed first as it works very quickly to prevent further clotting action.
- Warfarin which is usually prescribed after heparin to prevent new blood clots.
Direct acting oral anticoagulants (DAOCs) can also be used to treat Deep Vein Thrombosis. Apixaban and rivaroxaban are as effective as warfarin and heparin and may produce less serious side effects in many patients.
Medication isn’t the only treatment for DVT. Reducing the risk of complications and helping the body absorb blood clots may also involve the following treatment solutions.
While it isn’t established whether compression stockings can truly reduce the risk of DVT or prevent post-thrombotic syndrome, compression stockings may still be recommended by your physician.
Inferior Vena Cava (IVC) Filters
An IVC filter may be used instead of anticoagulant medication, usually when medication doesn’t work or needs to be discontinued due to side effects. An IVC filter is a tiny mesh device that’s installed in a vein to catch pieces of a blood clot and prevent it from travelling to the lungs or heart. An IVC filter is placed in a simple procedure under local anaesthesia through a catheter.
Staying active with low intensity exercise like walking can reduce the symptoms of DVT and may reduce your risk of complications.
Elevating Your Leg
You will probably be advised to elevate your leg when you rest to relieve pressure on the veins in the calf. This also reduces fluid and blood accumulating in the lower legs. Your foot should be elevated higher than your hip to help blood return from the lower leg.
Complications of Deep Vein Thrombosis
The greatest threat of DVT is not the pain and swelling it can cause but the life-threatening complications that may result from untreated DVT.
Pulmonary Embolism (PE)
When DVT isn’t treated, about 10% of people develop a very serious and life-threatening condition called a pulmonary embolism or PE. A pulmonary embolism is a medical emergency.
A pulmonary embolism happens when a deep vein clot dislodges and travels into the lung. PE can cause symptoms such as:
- Difficulty breathing
- Sharp chest pain, especially when taking a deep breath
- Heavy sweating
- Racing heart rate
- Feeling light-headed, dizzy, or faint
- Coughing up blood or a foamy pinkish mucus
About one-third of people who have an untreated, un-diagnosed pulmonary embolism die. The fatality rate drops significantly with prompt treatment, however.
A pulmonary embolism can also lead to another complication called pulmonary hypertension. This happens when the blood pressure in the lungs and right side of the heart is too high. This forces the heart to work even harder to pump blood through an obstruction in the artery of the lung which can weaken the heart.
Post-Thrombotic Syndrome (PTS)
PTS is a fairly common consequence of Deep Vein Thrombosis and it happens when DVT weakens or damages the veins in the lungs. Post-thrombotic syndrome can happen weeks or even months after developing DVT.
Veins in the leg are responsible for transporting oxygen-poor blood and waste to the heart while arteries deliver oxygen-rich blood to the body. The veins have small valves that keep blood moving toward the heart, but DVT can damage these valves and make them weak or even leaky. This allows blood to pool in the legs and cause PTS symptoms.
Symptoms of post-thrombotic syndrome may be very mild or severe depending on the person. These symptoms can include:
- Leg pain that gets worse with standing but better during rest
- Swelling of the leg
- Cramping, tingling, or itching of the leg
- A sense of heaviness of the leg
- Discolouration of the skin of the leg
Chronic Venous Insufficiency
Venous insufficiency happens after DVT when a vein in the leg no longer works as it should. This is a chronic condition that causes blood to stay in the vein rather than moving back to the heart. This increases pressure in the leg veins and causes damage to the lower leg, especially around the ankle.
Prevention of Deep Vein Thrombosis
There are many strategies to prevent the development of Deep Vein Thrombosis, but the best preventative measures will depend on your unique risk factors.
If you are undergoing surgery or you will be in hospital and unable to walk or get out of bed for an extended period of time, your doctor may recommend medication to reduce the risk of blood clots. You may need to take these medications before and after surgery. Inflatable compression devices may also be used. These devices inflate at regular intervals and squeeze the legs to improve blood flow. As soon as you are able, get up and walk after your procedure.
Ahead of a long trip, there are several ways to reduce the risk of DVT, especially if you are considered high-risk.
- Get up to walk and stretch often. Make frequent stops when travelling by car. During air travel, get up to walk down the aisle and stretch as often as possible.
- Wear loose-fitting clothing and especially avoid trousers that may cut off circulation to the legs.
- Drink plenty of water.
- Wear compression stockings after speaking with your doctor.
Your doctor may recommend medication and other treatments if you are pregnant and at high risk of DVT. This may be the case if you need bed rest, have inherited thrombophilia, have a family history of DVT, or you are likely to have a C-section.
There are also ways to reduce your risk of Deep Vein Thrombosis by making lifestyle changes:
- Quit smoking. Smoking makes platelets in the blood “sticky” and damages the lining of the blood vessels. Both of these factors make clots more likely to develop.
- Exercise regularly. An exercise regimen can improve your cardiovascular health and reduce the risk of DVT or PE from happening again. Make a goal to walk for 30 minutes about five times per week, starting with short five-minute walks several times a day.
- Eat a healthy diet. High cholesterol is a risk factor for hardening of the arteries and it can cause blood clots by allowing plaque in the arteries to rupture or tear. When the fatty material in plaque is exposed, it triggers a blood clot to form. Work on adopting a healthy diet rich in whole-grain wheat, fresh fruit and vegetables, and lean meats.
- Maintain a healthy weight. Being overweight or obese increases the risk of DVT for several reasons. People who are obese tend to be less active than people at a healthy weight. Obesity can also trigger inflammation that makes blood more likely to clot. Being overweight can also increase the risk of type 2 diabetes which is linked to blood clots.
Deep Vein Thrombosis FAQs
Q: Does a pulmonary embolism have symptoms?
A: Unfortunately, many people do not realise they have Deep Vein Thrombosis until a clot dislodges and travels to the lung, a serious condition called a pulmonary embolism. If you have a pulmonary embolism, you may experience shortness of breath, chest pain when you inhale deeply, the sensation that your heart is beating very fast, a cough, or a fever. You may also get dizzy as your blood pressure drops. Some people cough up blood as well.
Q: How is Deep Vein Thrombosis diagnosed?
A: After reviewing your medical history and conducting an exam, your physician will verify DVT by performing a non-invasive ultrasound that evaluates deep veins for clots.
Q: How common is Deep Vein Thrombosis?
A: DVT occurs in nearly 1 out of every 1,000 people in the general population of the UK each year. About 1 out of every 100 people aged 80 and older develop DVT.
Q: What are the risk factors for DVT?
A: While DVT is most common in older adults, it can also occur in younger people. There are several risk factors that can make you more likely to develop Deep Vein Thrombosis:
- Genetics. People with a family history of blood clots or an inherited tendency to clot are more likely to develop DVT.
- Age. DVT usually occurs in people over 40. The risk of DVT increases with age.
- Hormonal changes. Women are at an increased risk of DVT while taking hormone therapy or oral contraceptives and while pregnant or after recently giving birth.
- History of DVT. People who have a history of DVT or pulmonary embolism are at an increased risk of developing the condition again.
- Recent surgery. DVT often occurs in people who recently underwent surgery, especially surgery on the knees, hips, pelvis, or legs.
Q: What is Post-Thrombotic Syndrome?
A: Post-Thrombotic Syndrome (PTS) happens when DVT causes damage to the legs or veins. This condition often develops over a long time and causes swelling, discolouration of the skin, pain, and ulcers of the skin. About 40% of people with DVT develop PTS which varies in severity.
Q: How can I reduce the swelling and pain of DVT?
A: If you have been diagnosed with DVT, it’s important to keep your leg elevated when lying down or sitting. Walking, swimming, and other forms of gentle exercise can also help. It’s important to wear graduated compression hosiery to reduce the risk of post-thrombotic syndrome.
Q: When will the clot and symptoms go away?
A: Blood thinners are a standard part of treatment for DVT, but these medications will not actually dissolve the clot in your leg. Instead, the body will absorb the clot over a period of weeks or months. As this occurs, your symptoms will improve gradually.
While most patients recover from DVT without long-term effects, about 50% of DVT patients have a residual clot. This will be confirmed about 6 months after the acute clot is detected. The good news is this clot will not break off as it’s scar tissue in the vessel. Other blood vessels will bypass the damaged or narrowed veins and you may have no remaining symptoms. Unfortunately, some patients experience long-term problems due to damage from clot formation and chronic obstruction from the residual clot. This is called post-thrombotic syndrome.
- How to Reduce Appearance of Varicose Veins
- What is Chronic Venous Insufficiency?
- Should I have my Varicose Veins Treated?
- Will Varicose Veins Disappear after Pregnancy?
- Varicose Veins Diagnosis & Management Guidelines by NICE