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The Dangers Of DVT: Don't Ignore These Signs

Medically reviewed by Carmen Fookes, BPharm. Last updated on July 12, 2022.

Pain Or Cramping

A deep vein thrombosis (DVT) is a blood clot that occurs in a deep vein. Deep veins lie deep within the body and carry the vast majority of blood back to the heart, in contrast to superficial veins that are sited close to the skin's surface and carry minimal blood.

A clot in a deep vein can partially or totally obstruct blood flow. This causes the blood to pool and stagnate, stretching tissues and causing symptoms such as pain, cramping, and swelling.

DVTs that form in lower leg veins cause lower calf pain. DVTs can also form in other places in the body such as the arms (symptoms include arm pain) or in the abdomen and pelvis (causing lower back pain).

Skin Reddening Or Feeling Of Warmth

Blood clots prevent the free-flow of blood around the body. Blood pooling can cause color changes in the overlying skin, giving it a bluish, purplish or reddish tinge. This color change usually happens over an area of skin, not just one localized point (as an example, for DVTs in the lower leg, a significant portion of the skin on the lower calf area changes color). The skin may also feel warm to the touch.

Pain or swelling located in just one small area is more likely to be a superficial clot, especially if you can feel a bump under the skin with your fingers.

Another condition that may resemble a DVT is a Baker's cyst. These are fluid-filled lumps that occur behind your knee. Symptoms include:

  • Pain
  • Stiffness
  • Limited range of motion and ability to bend your knee
  • Swelling of your knee and/or leg. Baker's cysts can also rupture causing swelling and redness in the lower leg.

Sometimes Fever

Some people develop a slight fever when they have a DVT; however, having a fever does not definitely mean you have a DVT as a fever can be caused by other factors such as an infection.

Fever has been associated with an increased risk of complications in people with a DVT. One study found pulmonary embolisms (when a bit of the DVT breaks off and lodges itself in the lungs) or infections more common in DVT patients with fever, leading to worse outcomes.

Sudden Breathlessness, Coughing Up Blood

A real concern with DVTs is their ability to enlarge or to fragment and break apart. Fragmentation sends smaller satellite clots into the bloodstream.

A pulmonary embolism (PE) is the name given to a blood clot that wedges in an artery in the lungs. PEs can occur as a complication of a DVTs. Other causes of PE include bone injury, cancer, and air emboli. Blockages of small arteries in the lungs starve lung tissue of oxygen. Symptoms vary depending on the extent of the area affected, and range from mild, barely noticeable chest discomfort and mild breathlessness, to sharp, severe chest pain, sudden breathlessness, a rapid heart beat, and coughing up blood.

Post-thrombotic Syndrome: Chronic Swelling, Discoloration And Pain

When a clot completely blocks a deep vein, our body tries to compensate by using neighboring, smaller veins to bypass the obstruction. These collateral veins enlarge as they try to cope with more blood flow than normal. Some become quite large and reasonably effective at returning blood back to the heart. Others remain small and are ineffective, and as a result, blood pools in the tissues causing chronic swelling, pressure and pain. In addition to skin discoloration, texture changes - such as dryness and thickening - occur.

Doctors use several different terms to describe this symptom complex including post-thrombotic syndrome, post-phlebitic syndrome, or venous insufficiency syndrome.

May Increase Risk Of Heart Attack And Stroke Years Later

Even though a DVT occurs in a deep vein, and heart attacks and strokes occur in arteries, a Danish study found a 60% increased risk of heart attack and a more than doubling of the risk of stroke within one year of a DVT episode.

The news was worse for people who had suffered a PE. Those with a history of PE were twice as likely to have a heart attack and three times more likely to have a stroke in the first year after a PE than people who had never had a PE.

What Are My Risks Of Getting A DVT

People who are obese, smoke, or have a previous personal or family history of a DVT are more at risk.

Prolonged immobility also increases risk, for example, being bedridden following surgery, injury, illness, stroke, or long periods of sitting. Whether "Economy Class Syndrome" - the reported increased risk of DVT following long distance air travel - exists or not is contested - most experts believe the risk lies with prolonged immbolization that can occur with any type of travel - bus, boat, train, or car, rather than just the air cabin environment.

The CDC recommends:

  • Calf muscle exercises and sitting in an aisle seat so you can walk up and down the aisle frequently
  • People at risk of blood clots should consider properly fitted compression stockings to wear during travel and talk to their doctor about taking medications to reduce their risk of blood clots.

Conditions that slow blood flow (such as heart failure, varicose veins, and phlebitis), make the blood more likely to clot. Cancer, inherited clotting disorders, pregnancy, or estrogen-containing medicines also increase the risk.

Lowering Your Risk Of A DVT

Every hospital should focus on preventing DVTs in the first place. This means identifying at-risk patients before surgery or during their hospital stay and implementing measures such as mobilization, compression stockings, or use of medications in an attempt to reduce the risk of a DVT forming.

Sometimes this can be challenging, particularly if a person also has factors that increase their risk for bleeding, such as kidney disease, clotting disorders, or a spinal lesion.

Losing weight if you are overweight, stopping smoking, keeping certain conditions (such as heart failure or atrial fibrillation) under good control as well as regular exercise can all help to reduce the risk of a DVT.

Managing A DVT

If you have been diagnosed with a DVT your doctor is likely to put you on an anticoagulant.

Anticoagulants reduce the ability of your blood to clot, in effect "thinning" the blood. This helps prevent the DVT from getting bigger, reduces the risk of additional clots developing, and gives your body time to dissolve the clot. Treatment is usually required for at least three months. Examples of anticoagulants include:

"Clot busters" (such as Tissue Plasminogen Activator, or TPA) may also be used in intensive care situations to break up severe clots.

Finished: The Dangers Of DVT: Don't Ignore These Signs

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  • Barba R, DeMicco P, Blanco-Molina A, et al. Fever and deep venous thrombosis. Findings from the RIETE registry. J Thromb Thrombolysis. 2011 Oct;32(3):288-92. doi: 10.1007/s11239-011-0604-7.
  • NHS. Deep Vein Thrombosis. Symptoms.
  • Baker's Cyst. Cleveland Clinic. 09/04/2020.
  • Reyes N, Beckman M, Abe K. Deep Vein Thrombosis & Pulmonary Embolism. CDC Yellowbook

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.