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Deep Vein Thrombosis

PNS SHIFA

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Syed Intisar Hussain

Overview

Deep vein thrombosis (DVT) is a blood clot in a vein located deep within the body, usually in the leg, thighs, or pelvis. However, the clot can form in any other vein of the upper and lower extremities. DVT occurs when a blood clot forms in one or more veins in the body. It usually occurs in the legs and may cause pain or swelling. DVT may sometimes not show any noticeable symptoms. In addition, DVT can be secondary to certain medical conditions that affect the clotting of blood or can also develop if you don&rsquo;t move your legs for a very long time. For example, in case of a lack of movement because of an illness or accident, when you are on bed rest because of surgery, or during long-haul traveling.&nbsp;

Deep vein thrombosis can be a life-threatening condition because the blood clots in the veins can dislodge, travel through the bloodstream, and block blood flow in the lungs, also called pulmonary embolism. When DVT and pulmonary embolism (PE) occur together, it is referred to as venous thromboembolism. As many as half the people with DVT present with symptoms of intermittent leg pain and swelling, occurring over months to years.&nbsp;

&nbsp;

The symptoms are known as post-thrombotic syndrome and occur because of damage to the valves and inner lining of the veins which leads to &ldquo;pooling&rdquo; of blood. This leads to an increase in pressure inside the veins, resulting in pain and swelling. In the United States, 1 &ndash; 3 adults per 1,000 are diagnosed with DVT or pulmonary embolism annually<a href="#accordion">[1]</a>. Whereas up to 300,000 people die because of DVT/PE each year<a href="#accordion">[1]</a>. After heart attacks and strokes, it is the third most common vascular disease in the world. DVT can occur at any age but is more common in people over the age of 60<a href="#accordion">[1]</a>. However, it is less common in children and adolescents. In addition, more than half the cases of DVT are reported following a medical illness or surgery, as a result of a hospital stay or lying in bed most of the time. This increases pressure inside the veins, causing pain and swelling. Other characteristics of the condition include pooling of blood, swelling in the legs, increased pressure in the veins, leg ulcers, and discoloration or increased pigmentation of the skin. 
&nbsp;

Deep vein thrombosis can be of two types:&nbsp;

<ul>
	<li>Acute Deep Vein Thrombosis: Acute deep vein thrombosis is a common condition that may occur in women and men of all ages. It can cause swelling, pain, and limited movement.&nbsp;&nbsp;</li>
	<li>Chronic Deep Vein Thrombosis: A chronic DVT is one where the clot has been present for over a month or two. Over time the clot hardens and scars the veins, resulting in ineffective blood flow and pain.&nbsp; 
	&nbsp;</li>
</ul>

The severity of the disease can be classified as:&nbsp;

<ul>
	<li>Provoked: DVT can be triggered due to surgery, cancer, <a href="https://www.merisehat.pk/disease/obesity" target="_blank">obesity</a>, immobility, trauma, and oral contraceptives.</li>
	<li>Unprovoked:&nbsp;Unprovoked DVT can be because of idiopathic (relating to any spontaneous disease or condition for which the cause is unknown) or endogenous (internal cause or origin) reasons. In addition, patients are more likely to suffer from this severity of DVT if anticoagulants (drugs used to reduce the risk of blood clots) are discontinued.</li>
	<li>Proximal: Proximal DVT occurs above the knee and affects the femoral or iliofemoral veins. It is much more likely to lead to complications such as pulmonary emboli.&nbsp;</li>
	<li>Distal: In this type of DVT, the clot is located below the knee. 
	&nbsp;</li>
</ul>

Signs And Symptoms

Deep vein thrombosis usually forms in the veins of the legs, thighs, or pelvis. However, according to the CDC, the symptoms only occur in half the people with this condition<a href="#accordion">[1]</a>. Most people with DVT either don&rsquo;t have any symptoms or the symptoms are very mild and not a cause of concern. Classic symptoms of DVT are swelling, warmth, pain, tenderness to touch, and redness in the affected leg. The symptoms commonly associated with DVT include:&nbsp;

<ul>
	<li>One-sided swelling in the leg, foot, or ankle</li>
	<li>Pain, tenderness, or cramping in the affected leg that usually begins in the calf</li>
	<li>Severe, unexplained pain in the foot or ankle</li>
	<li>An area of the skin feels warmer than the skin in the surrounding areas</li>
	<li>Bluish or red discoloration, or skin turning pale (depending on the skin tone)&nbsp;over the affected area 
	&nbsp;</li>
</ul>

People with a blood clot in the upper extremity (arm) may not present with any symptoms, but it is possible to present with the following symptoms:&nbsp;

<ul>
	<li>Neck pain&nbsp;</li>
	<li>Shoulder pain&nbsp;</li>
	<li>Swollen arm or hand&nbsp;</li>
	<li>Blue or darker discoloration of the skin&nbsp;</li>
	<li>Pain that radiates from the arm to the forearm</li>
	<li>Weakness in the hand 
	&nbsp;</li>
</ul>

In many cases, people may not find out that they have DVT till they have undergone treatment for pulmonary embolism (blood clot in the lung). A pulmonary embolism occurs when the blood clot has moved from the arm or leg into the lungs. This is a life-threatening condition and may cause blockage of an artery in the lungs.&nbsp;

&nbsp;

Causes

DVT is caused by a blood clot that prevents blood from properly circulating in the body. This may occur because of several reasons, including:&nbsp;

<ul>
	<li>Damage To A&nbsp;Blood Vessel &ndash; Damage to a blood vessel because of an injury can cause it to narrow or block blood flow. As a result, a blood clot may form.&nbsp;</li>
	<li>Surgery &ndash; Blood vessels can get damaged during surgery which may lead to the development of a blood clot. In addition, bed rest with restricted movement or no movement at all may also increase the risk of developing a blood clot.&nbsp;</li>
	<li>Reduced Mobility &ndash; Sitting frequently can cause blood to collect in the legs, especially the lower parts. If you don&rsquo;t move for long periods, the blood flow in your legs can slow down and cause a clot to develop.&nbsp;</li>
	<li>Certain Medications &ndash; Some medications put you at a higher risk of developing a blood clot e.g. oral contraceptive pills.&nbsp;&nbsp; 
	&nbsp;</li>
</ul>

Other conditions that may increase the risk of deep vein thrombosis include:&nbsp;

<ul>
	<li>Inherited or genetic conditions, e.g. Factor V Leiden thrombophilia that increase the risk of blood clots</li>
	<li>Cancer or cancer treatment, for example, chemotherapy&nbsp;</li>
	<li>Previous diagnosis or a family history of deep vein thrombosis</li>
	<li>Limited blood flow in the deep vein either because of immobilization, surgery, or injury</li>
	<li>Immobility for long periods, for example, sitting for a long time on an airplane, train, bus, truck, or car, and immobility after a serious injury or surgery</li>
	<li>Being pregnant&nbsp;</li>
	<li>Being older than 40 years; however, DVT can affect people of all ages</li>
	<li>Being overweight or obese&nbsp;</li>
	<li>Autoimmune diseases, for example, inflammatory bowel disease, vasculitis, or <a href="https://www.merisehat.pk/disease/systemic-lupus-erythematosus" target="_blank">lupus</a></li>
	<li>Use of tobacco products</li>
	<li>Varicose veins&nbsp;</li>
	<li>Use of birth control pills or hormone therapy&nbsp;</li>
	<li>Having a pacemaker or central venous catheter&nbsp;</li>
	<li>History of <a href="https://www.merisehat.pk/disease/covid-19" target="_blank">COVID-19</a></li>
</ul>

&nbsp;

DVT can often be difficult to diagnose because it may be confused with other conditions with similar signs and symptoms, such as inflammation of the veins, cellulitis, bacterial skin infection, and muscle injury. Moreover, DVT is also often misdiagnosed as <a href="https://www.merisehat.pk/disease/myocardial-infarction" target="_blank">heart attack</a> and <a href="https://www.merisehat.pk/disease/pneumonia" target="_blank">pneumonia</a>. Thus, it is important to look for clots in the veins or lungs using imaging tests needed to diagnose DVT. 
&nbsp;

<ul>
	<li>D-Dimer &ndash; D-dimer is a protein fragment in the blood that is made when a blood clot dissolves in the body. The level of D-dimer is often increased in people with DVT or pulmonary embolism. The test is useful for people with DVT. If the test results are negative, then you have a low risk of DVT. D-dimer test has poor specificity. Hence, it is typically used as an initial screening test, rather than to provide a confirmed diagnosis. The D-dimer test, in particular, is most reliable in individuals who have a low likelihood of pulmonary embolism/deep vein thrombosis.</li>
</ul>

&nbsp;

Diagnosis

If the history, symptoms, and tests including D-dimer and physical examination suggest DVT, Duplex ultrasonography, and compression ultrasonography of the leg veins are advised to confirm the diagnosis. If the patient with DVT also has signs and symptoms of a pulmonary embolus, further testing for Pulmonary embolism may additionally be needed.&nbsp; 
&nbsp;

<ul>
	<li>Duplex Ultrasonography &ndash; Duplex ultrasonography is a standard imaging test for DVT that looks at the flow of blood in the veins using sound waves. The test can help detect blockages and blood clots deep in the veins.&nbsp;</li>
	<li>Contrast Venography &ndash; Contrast venography is a special X-ray in which a dye or contrast material is injected into a large vein, either in the foot or ankle, to see the deep veins in the leg and hip.&nbsp;</li>
	<li>Magnetic Resonance Imaging (MRI) &ndash; An MRI is an imaging test that uses radio waves and a magnetic field. It helps doctors diagnose a variety of medical conditions.</li>
	<li>Compression Ultrasonography &ndash; Compression ultrasonography is a commonly used medical ultrasound technique that uses sound waves to generate pictures of the structures inside the leg. In this type of examination, you lie on your back and a probe is placed on the skin. Sound waves are used to form an image of the tissue beneath. This is the test of choice in most circumstances for patients suspected of DVT.&nbsp;</li>
	<li>Other Imaging Tests &ndash; Imaging tests are done if ultrasonography is not possible to perform for some reason. The tests include MRI, CT scan, and contrast venography in which a dye is injected into a vein and an X-ray is done.</li>
	<li>Cause Of The Blood Clot &ndash; After the diagnosis of DVT is confirmed, the clinician will test for possible causes of DVT. Some obvious risk factors of DVT include recent surgery or immobility. Whereas, in some cases, the clinician may test for thrombophilia (a blood disorder that causes the blood in your veins and arteries to clot) and other conditions that increase the risk of DVT, such as cancer.&nbsp;</li>
</ul>

&nbsp;

Treatment

People with certain acquired and inherited abnormalities may require additional preventive measures and treatment to reduce the risk of DVT. The goal of treatment for DVT is to prevent the clot from becoming larger, new blood clots from forming, and prevent long-term complications. The primary approach of treatment for DVT is anticoagulation to reduce the risk of clot formation.&nbsp;

&nbsp;

Anticoagulation&nbsp;

The primary treatment approach for DVT is anticoagulation. Whereas other treatment options for specific situations may include thrombolytic therapy or placing a filter in a major blood vessel. Anticoagulants are medications that are commonly referred to as &ldquo;blood thinners&rdquo;, these medications do not dissolve the clot but prevent other clots from forming. There are several different anticoagulants that may be given for the diagnosis of DVT, including:&nbsp;

<ul>
	<li>Direct oral anticoagulants: these are anticoagulants available in pill form.&nbsp;</li>
	<li>Low molecular weight (LMW) heparin: LMW heparin is injected under the skin.&nbsp;&nbsp;</li>
	<li>Unfractionated heparin: this type of anticoagulant is given intravenously (into a vein), or as an injection under the skin. Unfractionated heparin is often a medication of choice for certain circumstances, for example, if a person requires dialysis for kidney failure.&nbsp;</li>
</ul>

&nbsp;

The choice of anticoagulants depends on several different factors, such as the patient&rsquo;s preference, cost considerations, and what the doctor recommends based on the patient&rsquo;s medical history. The duration of treatment for anticoagulation is a minimum of three months in patients with DVT. If there are reversible risk factors contributing to DVT, for example, surgery, trauma, or being confined to a bed for a long period, the doctor will likely recommend anticoagulation therapy for three months or until the risk factors have resolved.&nbsp;

Researchers suggest that people with DVT, who do not have a known risk factor, may not require treatment with anticoagulation for an indefinite time. However, the doctor will reassess the situation regularly and continue anticoagulation if needed. Some people may prefer to continue treatment with anticoagulation, though, this carries a risk of bleeding.&nbsp;Whereas others may prefer to stop their treatment with anticoagulants, however, this may increase the risk of recurrence of DVT.&nbsp;

Most experts recommend continuing anticoagulation indefinitely in case of two or more episodes of DVT or if there is a risk factor for clotting, for example, cancer.&nbsp;

&nbsp;

Walking With DVT

Once anticoagulation therapy has been started and symptoms such as pain and swelling are under control, it is recommended that patients get up and walk around periodically. Studies have further shown that there is no increased risk of complications in people who walk. Waking may help patients feel better sooner.&nbsp;

&nbsp;

Thrombolytic Therapy&nbsp;

In severe life-threatening cases, medication is recommended to dissolve blood clots. This is known as thrombolytic therapy. This medication can be given through an IV (called systemic thrombolysis) or via a catheter navigated to the site of the clot (called catheter-directed thrombolysis) Thrombolytic therapy is prescribed for patients with serious complications related to DVT.&nbsp;

&nbsp;

Inferior Vena Cava (IVC) Filter&nbsp;

An inferior vena cava filter is a device used to block the circulation of clots in the bloodstream. The device is placed in the inferior vena cava, the large vein that leads from the lower body to the heart. The filter is typically inserted in the leg vein through a small incision using a local anesthetic. An IVC filter is recommended for people who cannot use anticoagulants because of a high risk of bleeding. However, IVC filters can increase the risk of blood clots in the long term. IVC filters do not protect against DVT, rather they offer protection against life-threatening pulmonary embolism in DVT patients.&nbsp;

&nbsp;

Compression Stockings&nbsp;

Elastic compression stockings are useful for improving and completely getting rid of leg swelling, which is often caused because of damage to the small valves inside the veins. The swelling may also be caused because of the DVT blocking the flow of blood in your vein. Most of the compression stockings are worn just below the knee and are tight at the ankle, which causes gentle compression on the leg. Some people may need to wear the stocking for a year or more. Several clinical studies have shown that the daily use of compression stockings improves leg pain and swelling by at least 50%. However, the socks do not need to be worn overnight.

In some cases, such as after surgery, compression devices are also used to put pressure on the calves while lying in bed. The devices help prevent DVT if you are in the hospital. However, they are not prescribed outside the hospital.&nbsp;

&nbsp;

Complications from deep vein thrombosis can be quite serious, including:&nbsp;

<ul>
	<li>Pulmonary Embolism &ndash; A pulmonary embolism occurs when a part of the clot separates from the vein and travels to the lungs. The blood clot cuts off the flow of blood to the lungs and is a medical emergency that can cause death.&nbsp;</li>
	<li>Chronic Venous Insufficiency &ndash; Chronic venous insufficiency may occur following a deep vein thrombosis of a leg vein. It is a long-term condition in which the vein fails to function and the blood stays in the vein, instead of going back to the heart. Common symptoms of chronic venous insufficiency include pain and swelling.&nbsp;</li>
	<li>Post-Thrombotic Syndrome &ndash; Post-thrombotic syndrome may also happen secondary to deep vein thrombosis. The symptoms of post-thrombotic syndrome include pain, swelling, redness, and ulcers. In addition, ulcers and sores may also happen if the condition is not treated early.&nbsp;</li>
</ul>

&nbsp;

Several factors increase the risk of developing deep vein thrombosis, including:&nbsp; 
&nbsp;

<ul>
	<li>Age&nbsp;&ndash;&nbsp;While DVT can occur at any age, being older than 60 years increases the risk of DVT.&nbsp;</li>
	<li>Lack Of Movement&nbsp;&ndash; Muscle contraction helps with blood flow, but when the legs don&rsquo;t move for a long time, the muscles don&rsquo;t contract, which increases the risk of developing DVT. Sitting for a long time, for example, when flying, driving, and a lengthy hospital stay can increase the risk of DVT.</li>
	<li>Injury Or Surgery&nbsp;&ndash;&nbsp; Injury to the veins increases the risk of developing DVT.&nbsp;</li>
	<li>Pregnancy&nbsp;&ndash;&nbsp; The risk of blood clots increases in pregnancy, because of an increase in pressure in the veins and the pelvis. This may continue for up to 6 weeks after giving birth. In addition, people with an inherited clotting disorder are at a higher risk of developing blood clots.&nbsp;</li>
	<li>Hormone Replacement Therapy Or&nbsp;Birth Control Pills &ndash; Both hormone replacement therapy and birth control pills increase the risk of developing blood clots.&nbsp;</li>
	<li>Being Overweight Or <a href="https://www.merisehat.pk/disease/obesity" target="_blank">Obese</a><a href="https://www.merisehat.pk/disease/obesity" target="_blank"> </a>&ndash; Being overweight increases pressure in the pelvis and legs and the risk of developing DVT.&nbsp;</li>
	<li>Smoking &ndash; Smoking affects the flow of blood and can increase the risk of DVT.&nbsp;</li>
	<li>Cancer &ndash; Cancers and cancer treatments increase the risk of blood clots.</li>
	<li>Heart Failure &ndash; Heart failure increases the risk of DVT&nbsp;because the heart and lungs are not working well.&nbsp;</li>
	<li>Inflammatory Bowel Disease &ndash; <a href="https://www.merisehat.pk/disease/ulcerative-colitis" target="_blank">U</a><a href="https://www.merisehat.pk/disease/ulcerative-colitis" target="_blank">lc</a><a href="https://www.merisehat.pk/disease/ulcerative-colitis" target="_blank">erative colitis</a> and Crohn&rsquo;s disease increase the risk of DVT.&nbsp;</li>
	<li>Previous history or family history of DVT or PE; if you have a family history of DVT or PE, you may be at a higher risk of developing DVT.&nbsp;</li>
	<li>Genetics &ndash; Certain DNA changes may cause the blood to clot more easily, for example, V Leiden, which is an inherited disorder that changes clotting factors (factors that are involved in the clotting of blood) in the blood. However, inherited disorders alone may not cause blood clots, unless combined with other risk factors.</li>
</ul>

&nbsp;

People with acquired and inherited abnormalities are at a higher risk of developing DVT and may require additional preventive measures and treatment. Experts recommend that people with a family history of DVT, a history of inherited blood disorders, or genetic conditions should be screened for DVT. Below are some measures through which deep vein thrombosis can be prevented:&nbsp;

<ul>
	<li>People With Cancer &ndash; In some cases, such as in people undergoing cancer treatment who are at an increased risk of DVT, anticoagulation may be considered.&nbsp;</li>
	<li>During Hospitalization &ndash; People who are in the hospital either because of surgery, such as joint or cancer surgery, or a serious medical illness may also be given anticoagulants for decreasing the risk of blood clots. Anticoagulants can also be given to women who are at a high risk of developing deep vein thrombosis after pregnancy.</li>
	<li>Other Preventive Measures &ndash; In people who have a moderate to low risk of developing blood clots or in people who are hospitalized, preventive measures such as the use of fitted and inflatable compression devices may be used. The compression devices are inflatable and are worn around the legs to apply gentle pressure to improve circulation. However, walking as soon as possible after surgery in all cases can decrease the risk of blood clots and chronic swelling in the legs.&nbsp;</li>
	<li>Prolonged Travel &ndash; In case of prolonged travel, for example, on a car ride that is longer than 5 hours or airplane flight, the risk of developing blood clots increases. 
	&nbsp;</li>
</ul>

Below are a few tips that may help prevent swelling and deep vein thrombosis:&nbsp;

<ul>
	<li>Standing up and walking every hour or two</li>
	<li>Wearing loose, comfortable clothing</li>
	<li>Flexing the knees and ankles frequently, avoiding sitting with crossed legs and changing positions while seated</li>
	<li>Knee-high compression stockings</li>
</ul>

&nbsp;

Key Points

<ul>
	<li>Deep vein thrombosis is a potentially dangerous condition, characterized by a blood clot in a vein, usually in the legs, thighs, or pelvis. However, the blood clot can form in any other vein in the upper extremities as well.</li>
	<li>Deep vein thrombosis can be of two types: acute or chronic.</li>
	<li>DVT can often be difficult to diagnose because it may be confused with other conditions with similar signs and symptoms, such as inflammation of the veins, cellulitis or bacterial skin infection, and muscle injury. Similarly, it is often misdiagnosed as a <a href="https://www.merisehat.pk/disease/myocardial-infarction" target="_blank">heart attack</a> or <a href="https://www.merisehat.pk/disease/pneumonia" target="_blank">pneumonia</a>.&nbsp;</li>
	<li>The purpose of treatment in DVT is to prevent the clot from becoming larger, new blood clots from forming, and preventing long-term complications.</li>
</ul>

&nbsp;