Deep Venous Thrombosis (DVT)
AUTHOR: Ravi S. Sidhu MD, MEd, FRCS(C), FACS
What is Deep Venous Thrombosis?
Deep venous thrombosis (DVT) means formation of a blood clot in the deep veins of the legs. Veins are the 'pipes' that bring blood back to the heart. In the legs, there are superficial veins (close to the skin) and deep veins (between the muscles). When the blood clots in these deep veins, it is called a DVT.
What causes Deep Venous Thrombosis?
There are many risk factors for DVTs. These can be grouped into one of three categories. These categories and the corresponding risk factors include:
What are the symptoms of Deep Venous Thrombosis?
The most common symptoms of DVT are calf pain and swelling. It is well established that patients with these symptoms may not have a DVT and that patients with a DVT may have few symptoms. The first presentation might be of a pulmonary embolism. These symptoms include shortness of breath, chest pain, and palpitations.
Diagnosis and tests for Deep Venous Thrombosis
The most commonly used test for DVT is the duplex ultrasound. In this test, the veins of the leg can be directly visualized and assessed for the presence of clot. Other tests are only rarely used. These include CT scans, MRI, and contrast venography. In some settings, a physician may order a blood test called a D-dimer test. If this is negative, then it is unlikely that the patient has a DVT. However, a postive (or high value) has multiple causes hence further tests would be required in order to make the diagnosis of a DVT.
Lifestyle modification for Deep Venous Thrombosis
As noted above, the risk factors for DVT include immobility, trauma and disorders of blood that cause it to clot too quickly. Apart from encouraging early activity after surgery and avoidance of bedrest, there are few lifestyle changes that can prevent DVTs.
Non-surgical and medical management for Deep Venous Thrombosis
Prevention: Patients at high risk for DVT include those undergoing surgery, hospital inpatients, trauma patients, and cancer patients. The use of blood thinners (oral or injectable) have been shown to reduce the risk of DVT and pulmonary embolism in these patients. Mechanical devices such as calf compression pumps can also be used to prevent DVT.
Guidelines for Intervention for Deep Venous Thrombosis
In patients who have a DVT but cannot be on blood thinners because of active bleeding or recent surgery, a mechanical filter can be placed in the major vein draing the lower body. These filters are placed via the groins using a large 'I.V' tube. Most modern filters are designed to be removed once it is safe to thin the patient's blood again.
Surgical treatment for Deep Venous Thrombosis
Surgical treatment for DVT is very rare. In some patients, clot in the veins of the upper leg and pelvis cause so much back pressure in the leg that the tissues cannot receive adequate oxygen and nutrients. Under these circumstances, surgery is performed to physically remove the clot.
Endovascular Treatment for Deep Venous Thrombosis
Endovascular treatment for DVT was discussed above under indications for intervention.
When should I see my doctor?
If you have risk factors for DVT and have any symptoms, you should consult your physician. He / she will consider your particular case and proceed with investigations if necessary. If you have have a DVT in the past and now have symptoms of leg aching and heaviness, you may be experiencing post-thrombotic syndrome. Your physician would be able to advise treatment or arrange for appropriate referral.
References and Resources
Rutherfords Vascular Surgery. 7th Edition
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CSVS Guidelines for Abdominal Aortic Aneurysm screening
“The 2018 CSVS guidelines suggest all men 65-80 and all women who have smoked or have heart disease and are between the ages of 65-80 should have an abdominal ultrasound (US) to rule out an abdominal aortic aneurysm (AAA).
Those older than 80 can be considered for screening, but it is important to talk to your doctor. Speak to your primary care physician or vascular surgeon to ensure you have been screened.