Last Updated on August 9, 2021
Deep vein thrombosis (DVT) is a condition in which blood clots form in one or more of the deep veins of the body. The most commonly affected deep veins are those in the legs. Besides leg veins, the disease can also affect veins in the pelvis. It is a very serious condition and can be life-threatening.
Read more about Venous Drainage of Lower Limb
A blood clot is a clump of blood that has turned into a solid state. It is also called a thrombus.
Deep vein thrombosis can cause pain or swelling in the legs. In some cases, the patient may not have any symptoms.
DVT can lead to a very serious life-threatening condition called pulmonary embolism in which the blood clot breaks away from the vein, travels through the blood stream and lodges into the lungs.
When DVT and pulmonary embolism occur together, the condition is called venous thromboembolism (VTE).
Clinical features
About half of the patients suffering from DVT may not have any signs or symptoms. Common symptoms include:
- Swelling in the affected leg. The swelling may involve the foot, ankle, or leg. In rare cases, there may be swelling in both legs.
- Pain in the leg. The pain often begins in the calf region. It can be in the form of a cramping sensation or soreness. At times, the pain may be very severe.
- In case of DVT involving the arms, the patient may have pain in the neck, shoulder or arms, swelling in the arm or shoulder.
- Red, pale or discolored skin in the affected area.
- The skin over the affected area may feel warmer as compared to the surrounding area.
Pulmonary embolism: In some cases, the blood clots can break loose and detach from the veins. These blood clots may then travel through the bloodstream and get stuck in the lungs. This is called a pulmonary embolism. It is a life-threatening condition and requires emergency care.
In addition to symptoms of DVT, the patient may have the following symptoms in case of pulmonary embolism:
- breathlessness
- chest pain
- rapid breathing
- faster heart rate
- fainting
- coughing out blood
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Causes and risk factors
- Prolonged immobility leading to slow and sluggish blood flow
- Immobility for prolonged duration prevents the calf muscles from contracting. This prevents the normal flow of blood and can lead to DVT. Prolonged immobility can occur due to the following reasons.
- Being bed-ridden (due to a medical condition or after surgery)
- Prolonged sitting, especially with crossed legs (such as going on a long journey by plane, car or train)
- Paralysis
- Immobility for prolonged duration prevents the calf muscles from contracting. This prevents the normal flow of blood and can lead to DVT. Prolonged immobility can occur due to the following reasons.
- Damage to a vein
- Severe muscle injury
- Fractures
- Major surgery (involving the abdomen, pelvis, hip, or legs)
- Increased level of hormone estrogen in the body
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- Oral contraceptive pills
- Hormone replacement therapy
- Pregnancy, for up to 3 months after giving birth
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- Certain medical diseases:
- Heart disease
- Lung disease
- Inherited clotting disorders
- Cancer and its treatment- chemotherapy
- Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
- Other factors:
- Increasing age
- Obesity
- Smoking
- Varicose veins
- Personal history of DVT or pulmonary embolism.
- Family history of DVT or pulmonary embolism.
- Genetic factor: Some people inherit factor V Leiden which is a mutation of one of the clotting factors in the blood. This mutation can increase the chance of developing abnormal blood clots.
- No known risk factor
- At times, an abnormal blood clot may occur without any apparent underlying risk factor.
Complications
Pulmonary embolism
It is a life-threatening complication associated with DVT. It occurs when blood clots break loose from the veins, travel through the bloodstream and get stuck in a blood vessel in the lung.
It requires immediate medical treatment or can be fatal.
Postphlebitic syndrome
Blood clots can cause damage to the veins resulting in leg pain, swelling, skin discoloration, skin sores or leg ulcers (venous stasis ulcers).
Treatment complications
Anticoagulants or thrombolytic drugs used in the treatment of DVT can cause bleeding as a side effect.
It is important to have regular blood tests (such as INR ) while taking such medications.
Read more about Prothrombin time and international normalised ratio or PTI/INR
Prevention of deep vein thrombosis
Avoid prolonged immobility
In case you have had surgery or have been on prolonged bed rest for any reason, it is important to try and start moving as soon as possible.
In case of long distance traveling by car, it is better to take frequent breaks by stopping every hour or so and walking around for a few steps.
If traveling by train or plane, you can stand or walk occasionally.
If you need to sit for a long time, do not cross your legs, as it can block blood flow.
Don’t wear tight clothes as they can restrict blood flow.
Another way to prevent slowing of blood due to prolonged sitting is by exercising your lower legs while remaining seated. This can be done by raising and lowering the heels while keeping the toes on the floor. Also you can raise your toes while keeping the heels on the floor.
Maintain ideal body weight
Regular exercise, eating healthy food and adopting a healthy lifestyle can help to prevent obesity which is an important risk factor for DVT. It also prevents heart diseases, another risk factor for blood clots.
Judicious use of hormone therapy
Exogenous hormones in the form of oral pills for contraception or hormonal therapy for post-menopausal patients should be avoided in persons who are having other risk factors for DVT.
Adopt healthy lifestyle
This includes quitting smoking and consuming a healthy diet.
Diagnosis
Signs and symptoms, personal and family history and a thorough physical examination are all essential for the proper diagnosis of deep vein thrombosis. In addition, the following tests may be carried out to confirm the diagnosis.
D-dimer test
D-dimer is a protein fragment that is present in blood after a blood clot is lysed. A high level of d-dimer indicates a possible blood clot. D-dimer levels may also be raised due to trauma, certain inflammatory conditions, and after recent surgery.
In DVT, d-dimer levels remain elevated for about 7 days. In later course of the disease, the levels may be low.
Coagulation studies
These are done to evaluate for a hypercoagulable state. A prolonged prothrombin time or activated partial thromboplastin time is not indicative of a lower risk of thrombosis.
Duplex ultrasound
It is the most common test used to diagnose DVT. It shows the blood flow in the veins and detects any blood clots. It can also detect any alterations in blood flow, and whether the clot has developed recently or is an old one. In this procedure, pressure is applied on the arm or leg. If the pressure does not cause the vein to compress, it could indicate the presence of a blood clot.
Venogram
In this test a dye is injected into a vein in the leg. X-ray images are taken which can track the dye. Any blood clot or blockage in blood flow can thus be seen.
Other imaging scans
Magnetic resonance imaging (MRI)
It shows images of organs and other body structures.
Magnetic resonance venography (MRV)
It shows images of blood vessels within the body.
Computed tomography (CT) scan
It can help to identify blood clots in the abdomen, pelvis or lungs (pulmonary embolism).
Genetic testing
In case of suspicion of a genetic disorder, blood tests may be carried out to detect the specific gene mutation.
Treatment
Anticoagulants
They are also called blood thinners. They can prevent clots from getting bigger and also reduce the risk of developing more clots. They however, don’t break up existing blood clots.
Anticoagulants can be taken orally, intravenously or subcutaneously.
Two types of anticoagulants are most commonly used: heparin and warfarin. Heparin is given by intravenous route while warfarin is taken orally.
Other commonly used anticoagulants are enoxaparin, fondaparinux, apixaban, betrixaban, dabigatran, edoxaban, rivaroxaban, etc.
Anticoagulants may need to be taken for three months or longer. For recurrent DVT, life-long treatment may be required.
Patients on warfarin require regular blood tests such as INR to check how long it takes for blood to clot.
Thrombolytic drug
These are medicines that break down clots. They are required for patients with more severe DVT or pulmonary embolism who need immediate medical care.
Tissue plasminogen activator (TPA) is a commonly used thrombolytic drug. It is administered through a small catheter or tube, directly within the clot.
Excessive bleeding is a common side effect of these drugs. Hence, it is administered only in emergency situations.
Inferior vena cava filter
A tiny device is inserted into the inferior vena cava (a large vein that sends blood from the lower part of the body back to the heart). This device acts as a filter, catching and preventing the blood clots from traveling to the lungs while allowing the blood to flow normally.
Compression stocking
Compression stockings or special knee socks prevent swelling associated with deep vein thrombosis and also protect from post-thrombotic syndrome. They also prevent the pooling of blood and the tendency to clot.
To be effective, these should be worn at all times for at least 2 years.
Mechanical venous thrombectomy
This is a relatively new technique in which a deep vein clot is cut out.
It uses a catheter and a clot-removing device. Under imaging guidance, the catheter is inserted towards the clot. The clot-removing device is directed through the catheter towards the clot which then removes it using aspiration or a stent. This helps to reestablish blood flow.
References
- Buller HR, Ten Cate-Hoek AJ, Hoes AW, et al. Safely ruling out deep venous thrombosis in primary care. Ann Intern Med. 2009 Feb 17. 150(4):229-35.
- Tapson VF. Acute pulmonary embolism. N Engl J Med. 2008 Mar 6. 358(10):1037-52.
- Meignan M, Rosso J, Gauthier H, et al. Systematic lung scans reveal a high frequency of silent pulmonary embolism in patients with proximal deep venous thrombosis. Arch Intern Med. 2000 Jan 24. 160(2):159-64.
- Haeger K. Problems of acute deep venous thrombosis. I. The interpretation of signs and symptoms. Angiology. 1969 Apr. 20(4):219-23.
- McLachlin J, Richards T, Paterson JC. An evaluation of clinical signs in the diagnosis of venous thrombosis. Arch Surg. 1962 Nov. 85:738-44.
