Deep vein thrombosis (DVT) is a condition resulting from the formation of a blood clot inside a deep vein, commonly located in the calf or thigh.
DVT occurs when the blood clot either partially or completely blocks the flow of blood in the vein. When the blood flow slows down due to illness, injury, or immobility, there is a tendency for blood to accumulate or "pool." A stagnant pool of blood begins to clot and poses a potential risk for DVT.
In most situations, blood clots are a natural part of the healing process. They enable the injured tissue to begin to repair itself without excessive blood loss. In the case of deep vein thrombosis, however, the body signals the clotting process to occur unnecessarily at the wrong time and in the wrong place.
Will I get a DVT?
DVT can strike almost anyone at with the necessary risk factors. Factors and conditions that may increase the risk of DVT include:
Because immobility slows down the circulation of blood, anyone who sits immobile for hours at a stretch is at risk for DVT. This includes patients who are paralysed by a stroke, patients who are confined to bed after operations or illness, and passengers on long haul flights.
Blood vessels may be injured in a variety of ways including fractures and surgery or radiotherapy for cancer.
Inherited Clotting Disorders If blood clots run in your family, you may have an inherited clotting disorder. Among people of European descent, the most common genetic mutations that encourage clotting are the factor 5(V) Leiden and the prothrombin gene mutation. Individuals who inherit one of these mutations from either parent may experience recurrent episodes of DVT, but the risk is highest if both parents were affected.
Pregnant women are 5 times more likely to develop DVT than non-pregnant women. Cases occur most often in the third trimester and immediately following delivery. There is often a history of a minor clotting disorder on one side of the family.
Oral Contraceptives Hormonal preparations such as oral contraceptives or hormone replacement therapy may also increase the risk of clotting, particularly when combined with other risk factors like smoking.
Some cancers release substances that increase the blood's tendency to clot. Cancers of the ovaries and pancreas are particularly likely to provoke DVT.
Tobacco smoke reduces the amount of oxygen carried in the blood and may damage vessel walls, potentially leading to clot formation. It is one of the most modifiable risk factors for cardiovascular disease.
How will I know if I get a DVT?
DVT is notoriously difficult to diagnose just by looking. It may occur without any symptoms in up to 50% of cases. Contact your doctor if you notice:
- Pain, tenderness, or sudden swelling in the leg
- Discoloration or visibly large veins
- Skin that is warm to the touch
- What tests will I need?
Because several other conditions such as muscle strains, skin infections and phlebitis display symptoms similar to DVT, the condition may be difficult to diagnose without doing specific imaging studies. These are some of the tests that are used.
Doppler (Duplex Venous) Ultrasound - This is the most popular method for diagnosing DVT. It is it painless, fast and easy to perform, although it is not quite as accurate when looking for clot below the knee.
Venography - In this study, contrast is injected into a large vein in the foot or ankle. An x-ray image is then taken to reveal the location of possible clots. Venography is one of the most accurate ways to identify deep vein thrombosis, but it may be uncomfortable. Occasionally it may cause phlebitis, an inflammation of the superficial veins.
Is DVT dangerous?
Yes. It has life and limb threatening effects. Additionally, it can be a source of great long-term misery for some. The most dangerous complication of DVT is the development of pulmonary embolism (PE). A pulmonary embolism occurs when a blood clot breaks loose from the wall of a vein and travels to the lungs, blocking the blood flow from the heart. This may be life threatening. Symptoms of a pulmonary embolism may include:
- Shortness of breath
- Rapid pulse
- Excessive sweating
- Sharp chest pain
- Cough that may produce a bloody discharge
If you have experienced these symptoms and you are known to have a DVT, you should seek medical advice immediately. In some patients, a very large DVT may completely block the blood flow out of the leg or arm. Gradually the leg becomes swollen and then gangrene will set in.
This massive DVT (also known as phlegmasia cerulea dolens) is very rare and most often seen in patients with terminal cancer. It can be treated if diagnosed early enough. DVT can produce long-lasting damage to the venous valves and in some cases residual scarring and partial blockages. These can result in the formation of varicose veins as well as skin changes in the ankle area of the foot. These patients are at high risk of leg ulcers and recurrent DVT. Your surgeon will tell you more about this condition called the post phlebitic limb.
What treatments are there for DVT?
In most cases, once a DVT has formed it cannot be removed. Drugs are used to prevent it from spreading or breaking loose into the circulation.
Medications - Drugs generally used to treat deep vein thrombosis fall into 2 basic categories: anticoagulants and thrombolytic Agents. All of these drugs may cause bleeding and should only be taken under medical supervision. While taking these medications: Always read the product label and discuss potential side effects with your doctor. Take only the amount of medication prescribed, and do not change the dosage unless you have been instructed to do so. Do not take these medications with any over-the-counter medicines without checking with your doctor.
Anticoagulants Anticoagulants do not dissolve clots but prevent them from growing and new ones from forming. These medications include:
- Heparin - Given by skin injection or into a vein heparin thins the blood to prevent further blood clot forming over the DVT. In the meantime, the body's own mechanisms begin to dissolve the DVT. Prior to and after any major operation, you will be given a low molecular weight heparin to reduce your risk of developing a DVT in hospital. In patients with a new diagnosis of DVT, low molecular weight heparin is given as the blood levels are more stable, and you will not require frequent testing and monitoring.
- Warfarin - This is an oral anticoagulant. Warfarin therapy overlaps with low-molecular-weight heparin at the beginning. This is because it needs time to take effect - usually 3 to 5 days. Once blood tests confirm that warfarin is working adequately, the heparin can usually be stopped.
- Thrombolytic Agents - These drugs will dissolve clots. Administered through a vein or directly into the clot via catheter, they make the clot disintegrate. These are very potent drugs and can only be prescribed in hospitals. Close monitoring is required because the risk of bleeding complications is high. The main drug used is tissue plasminogen activator (TPA). At present, thrombolytic therapy is reserved for patients with new large clots and those who are at high risk of long-term complications due to a clotting disorder or other predisposing condition.
- Surgical Procedures - Patients who are unable to take anticoagulants (due to allergy or excess bleeding) or who develop pulmonary emboli while on therapy may require insertion of a filter or surgery to remove the clot.
DVT and flying
Don't let cramped conditions put you at risk of DVT. Keep your body moving - even when travelling by airplane. Take proper precautions to reduce the risk of "Economy Class Syndrome."
- Ankle Circles: Lift your feet off the floor and twirl your feet as if you're drawing circles with your toes. Continue this for 15 seconds, then reverse direction. Repeat as desired.
- Foot Pumps: Keep your heels on the floor and lift the front of your feet toward you as high as possible. Hold for a second or two, then flatten your feet and lift your heels as high as possible, keeping the balls of your feet on the floor. Continue for 30 seconds, and repeat as desired.
- Knee Lifts: Keeping your leg bent, lift your knee up to your chest. Bring back to normal position and repeat with your other leg. Repeat 20 to 30 times for each leg.
- Shoulder Roll: Lift your shoulders upward, then pull them backward, downward, and forward, creating a gentle circular motion. Continue for 30 seconds. Then reverse direction if desired.
- Arm Curl: Start with arms on chair rests, bent at a 90-degree angle. Raise one hand up to your chest and back down. Alternate hands and continue for 30 seconds. Repeat as desired.
- Knee to Chest: With both hands clasped around your right knee, bend forward slightly and pull your knee to your chest. Hold the stretch for 15 seconds; then slowly let your knee down. Repeat the same stretch with your left knee. Perform 10 stretches for each leg.
- Forward Flex: Keep both feet on the floor and slowly bend forward, reaching for your ankles. Hold the stretch for 15 seconds and slowly return to a normal seated position.
- Overhead Stretch: Raise both hands straight up over your head. Use one hand to grab the wrist of the opposite hand and gently pull to one side. Hold the stretch for 15 seconds, and repeat with the other arm.
- Shoulder Stretch: Bring your right hand over your left shoulder. Then place your left hand behind your right elbow and gently pull your elbow toward your body. Hold the stretch for 15 seconds and repeat with the other arm.
- Neck Roll: Relax your neck and shoulders. Then drop your right ear to your right shoulder and gently roll your head forward and to the other side, holding each position about 5 seconds. Repeat 5 times.
Try to keep your feet elevated by using the leg rests at the highest elevation. Rest your feet on your carry-on luggage if necessary.
If you have an opportunity to move around the cabin, walk to the restroom and back.
Drink plenty of fluids, preferably water, to avoid dehydration.
Walk for 30 minutes before boarding the plane.