Deep Vein Thrombosis (DVT)

What is Deep Vein Thrombosis?

Deep vein thrombosis (DVT) occurs when a thrombus or blood clot forms in a deep vein inside our body [1]. It commonly affects the thighs or legs but it can occur elsewhere in the body [2].


A blood clot forms when blood becomes thick and starts clumping together [2]. This blood clot becomes dangerous when it breaks off from the vein and travels in the bloodstream to the lungs [5], which in this case, it will be called embolism [1].

When this happens, major complications such as pulmonary embolism can happen, which is far more dangerous and life threatening because it may lead to lung damage. Furthermore, it blocks the transport of oxygen to the blood, thus all together affects not only the heart but also the other parts of the body.

Picture 1 : Pathogenesis of Deep Vein Thrombosis
Image Source: sirweb.org

There are two types of veins in the legs, the superficial vein and the deep vein [4]. Superficial veins are located just beneath the skin and can be visibly seen. Meanwhile, as its name suggests, deep veins are located deep within the legs and cannot be seen.

The condition is thus called “deep vein” thrombosis because only thrombosis that occur in the deep vein may lead to pulmonary embolism because blood flowing through the deep veins lead directly to the heart while superficial veins lead to perforated veins, which act like sieve to clots, before it even reach the deep veins.

Deep Vein Thrombosis Causes

Blood clots occur normally in our bodies. Microscopic clots are naturally present in our bodies, mainly as a result of physiological repairs, but are routinely broken down too.

If the balance between its formation and breakdown is altered, larger clots occur, which then combine to be a thrombus when different risk factors are present [4].

Blood clots can be caused by various reasons, mainly factors that alter blood flow in the vein; when the blood flow slows down or become stagnant.

Risk Factors

Injury/Trauma/Surgery

  • Injury to the vein after surgery decreases blood flow and increase risk of blood clots.
  • General anaesthetics increases vein diameter, which slows blood flow.
  • Surgery to the hip, knee and female pelvis more commonly develop DVT.
  • Fracture to the leg
  • Pacemaker catheter passed through the vein (mostly in the groin) irritate blood vessel wall and decrease blood flow.

Inactivity

  • Sitting for long periods of time (travelling by land or plane, driving)—blood clots may form when calve muscles of the leg don’t contract. Lack of movement means lesser blood circulation.
  • Bed rest—may be due to hospitalization or paralysis.

Genetics

  • Coagulation defects (Hypercoaguability – coagulation is faster than usual) Factor V Leiden – main hypercoaguability disorder. This factor cannot be inactivated by activated protein C which results to abnormal coagulation process.
  • Family history of blood clots — inherited disorder highly causes DVT if combined with other factors
  • Polycythemia – increased number of blood cells. May be caused by over production in the bone marrow.
  • Causes the blood to be thicker which results to slower blood flow.
  • Tallness – Taller men have better risk of developing blood clots than women.

Other diseases

  • Cancer — may increase substances that cause blood to clot; cancer treatments have the same effect.
  • Ulcerative colitis (a form of inflammatory bowel disease) – increases risk of DVT
  • Heart failure — ineffective pumping of the blood alters blood flow, thus increasing risk of DVT
  • Lupus — autoimmune disease; leads to inflammation.

Lifestyle

  • Cigarette smoking — smoking have effects on blood clotting and circulation.
  • Age — people aging over 50 increases risk of DVT, however, it can occur at any age.
  • Overweight or obesity – excess body fat increases pressure in the veins in the pelvis and legs
  • Taking birth control or hormonal pills — increases the blood’s ability to clot.

Pregnancy

  • Results to increase in blood pressure on the pelvis and legs. Risk of blood clots may continue six to eight months after childbirth.

If you have previous experience of having DVT before, there is a higher risk you’ll have it again. And also a higher risk of developing pulmonary embolism. [1, 3, 4]

Symptoms

Because a clot cuts down the blood supply, usually on the lower leg or thigh, a person with DVT mainly have the following symptoms:

  • Swelling of the leg
  • Redness or discoloration of the leg
  • The leg feels warm to the touch
  • Pain or tenderness in the leg

Picture 2 : Deep Vein Trombosis
Image Source: stoptheclot.org

These symptoms mimic other conditions such as cellulitis, so diagnosis for DVT is sometimes difficult [4].

Diagnosis of Deep Vein Thrombosis (Tests)

First and foremost, your doctor will perform a physical examination on you wherein he will assess swelling, tenderness or discoloration of the affected area. After that, he may require you to have further diagnostic test such as [3]:

  • Ultrasound – uses sound waves that may be reflected by the clot and show on the imaging machine.
  • Bloodtest – its purpose is to check if you have an elevated blood level of D-dimer, a clot dissolving substance. This is an indicator of DVT occurrence.
  • Venography – a dye will be injected in your vein and an x-ray test will be performed. The dye will serve as a contrasting agent to see if clots had developed in your vein.
  • CT or MRI scans – creates image if your veins to spot clots.

Complications

Some people are not aware that they even have DVT unless they experience symptoms of pulmonary embolism which include [2]:

  • Sudden shortness of breath
  • Coughing up blood
  • Pain when deep breathing
  • Dizziness
  • Fainting
  • Rapid heart rate
  • Anxiety

Treatment of Deep Vein Thrombosis

The first aid for deep vein thrombosis, or if it is just superficial, is warm compresses, taking anti-inflammatory drugs such as ibuprofen and leg compressions [4].When diagnosed with DVT, certain medications that will decrease your blood’s ability to clot, called blood thinners will be administered and prescribed by your doctor. Such as:

  • Heparin – given initially and given as an injection or through an IV tube, which means you will have to be admitted to the hospital.
  • Warfarin – may be administered together with heparin. Warfarin takes longer to have an effect, up to 2 or 3 days. But once warfarin starts to work, heparin medication is stopped. Warfarin is much preferred because it is taken by mouth. Note: Warfarin is dangerous during pregnancy [2].

Treatment of DVT by blood thinners usually lasts for 6 months. This may be changed if other conditions are concerned, like cancer and surgery.Blood thinners have a side effect of bleeding [2]. When blood than thinned so much, it results to bleeding because of the depleted ability to clot, which is essential in repair of wounds. This side effect can be life threatening. Bleeding can sometimes be internal, so people who take blood thinners must have regular blood tests to regulate the blood’s ability to clot.

Other treatments include thrombolytics, thrombin inhibitors, surgery, and pressure stockings.

  • Thrombolytics – used to dissolve large blood clots. Only used in life threatening situations because it causes sudden bleeding.
  • Thrombin inhibitors – interfere with blood clotting process. Inhibit blood clotting.
  • Vena Cava Filter (surgery) – a filter will be inserted inside the vena cava (a large vein). This filter will serve as a sieve for blood clots so that it will be prevented from entering to the lungs, so them pulmonary embolism may also be prevented. However, this filter does not stop new blood clots from developing [2].
  • Blood clot removal surgery – performed when there is obstruction of almost all blood return on a certain area, leading to total compromise on blood supply. Usually occurs in the iliac vein of the pelvis and femoral vein of the leg [4].
  • Compression stockings – tight to the ankle and looser as it reaches the leg. Creates a gentle pressure in the legs so that blood will continue flowing [3].

Prevention of Deep Vein Thrombosis

  • Prevention is a prime importance for all illnesses. As for DVT, minimizing risk factors is also the key.
  • First and foremost, if you are under medication for DVT, you must take the prescribed medication as directed.
  • Regulate your vitamin K intake because it has an effect on the drug warfarin [3]. Food rich in vitamin K include green leafy vegetables and soybean oils. And of course, have your regular check-ups to regulate your DVT.
  • During long hours of travel, you must move your legs whilst sitting or take a walk when break is allowed.
    When you have just undergone surgery, if possible, get out of your bed and take walks.
  • Stop smoking, and for women taking pills, it is imperative to really stop smoking.
  • And last but not the least, a healthy lifestyle is not at all bad and hard for you to prevent DVT. Loosen your weight and stay fit, control your blood pressure, and again, just quit smoking.

References:

  1. http://www.nlm.nih.gov/medlineplus/ency/article/000156.htm
  2. http://www.nhlbi.nih.gov/health/health-topics/topics/dvt/
  3. http://www.mayoclinic.com/health/deep-vein-thrombosis/DS01005.
  4. http://www.medicinenet.com/deep_vein_thrombosis/article.htm
  5. http://www.webmd.com/dvt/tc/deep-vein-thrombosis-topic-overview

Published on by under Diseases and Conditions.
Article was last reviewed on September 6th, 2016.



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