What is Deep Venous Thrombosis (DVT)? Blood Clot in Leg Vein

Deep venous thrombosis or DVT is a condition where a blood clot forms in one of the major deep veins, usually of the lower leg, thigh or pelvis. It can cause pain and swelling of the affected leg and its most dangerous consequence is the development of pulmonary embolism (blood clot in the lung). Rarely, DVT may occur in a deep vein in the arm.

There are two types of veins in the leg – superficial and deep. The deep veins lie under the muscles while the superficial veins lie just under the skin. Blood clots may sometimes form in the superficial veins but cause milder problems than when the deep veins are involved.

What causes deep vein thrombosis?

Causes of DVT

A blood clot or thrombosis may form within a blood vessel due to the following causes :

• Damage to the inner lining of the blood vessel due to any cause.
• Stagnation or slowing of blood flow within the vessel in case of a block.
• Increased turbulence of blood flow.
• Increased coagulability of blood.

Under these conditions, the clotting factors and other components of the blood may be activated. This mechanism is designed to seal and breaks in a blood vessel and prevent blood loss but in DVT, it is prematurely activated. The blood clot builds up within the vein and gradually grows in size.

Who is at risk of deep vein thrombosis?

Risk Factors for DVT

DVT is more likely to occur  in a who has one or more risk factors. Despite a known list of risk factors, DVT may occur in a person who is at low risk.

• Obesity
• Prolonged immobilization – as after major surgery (especially orthopedic, gynecologic or heart surgery), severe illness, fracture or injury.
• Immobility during a long journey, either by car or plane.
• Pregnancy
• Recent childbirth
• Oral contraceptives or hormone replacement therapy (HRT)
• Extremely high altitudes
• Age over 60
• Smoking
• Heart attack
• Family history
• Cancer
• Past history of DVT
• Disseminated intravascular coagulation (DIC)
• Chronic inflammatory diseases
• Genetic or inborn error in the clotting mechanism

What are the symptoms of deep vein thrombosis?

Signs and Symptoms of DVT

Some patients may be asymptomatic. Once the clot is large, it significantly hampers the blood flow returning to the heart. Deoxygenated blood pools in the leg, distending the limb and starving the tissue of a good supply of oxygenated blood carried by the arteries. The leg is prone to ulcers and infections. It may present with one or more of the following symptoms in the affected leg

• Swelling
• Redness
• Warmth
• Pain or tenderness, especially on standing or walking
• Leg cramps

What are the long term effects of deep vein thrombosis?

Complications of DVT

• Pulmonary embolism is the most serious complication of DVT. It may occur when a clot breaks loose and embeds in a blood vessel in the lung. This can cause symptoms such as shortness of breath, coughing up blood, rapid heart rate, and pain on deep breathing. Pulmonary embolism may become fatal in some cases.
• Post-thrombotic syndrome is a condition that occurs when the valves in the deep veins are damaged as a result of DVT causing blood to stagnate in the limbs instead of flowing upwards. This can result in pain, swelling and leg ulcers.
• Limb ischemia is a rare complication that arises with pressure in the veins. The arterial blood supply to the leg is compromised thereby leading to pain, ulcers and even gangrene of the leg.

How is deep vein thrombosis diagnosed?

Diagnosis of DVT

Tests and investigations help to identify hypercoagulability of the blood, visualize the blood clot and assess the flow of blood through the vein. These tests work hand-in-hand in reaching the final diagnosis. In addition, the tests may also indicate some underlying disorders, like a clotting disorder, which may be responsible for clot formation.

• D-Dimer blood test
• Doppler ultrasound
• Venogram

How is deep venous thrombosis treated?

Treatment of DVT

• Medication
  • Anticoagulants, such as heparin and warfarin, to stop formation of blood clots. Thrombolytics work by dissolving clots but are generally not used since it may cause severe bleeding.
• Graduated compression stockings may help to reduce pain and swelling, and may also prevent post-thrombotic syndrome.
• A vena cava filter may be used where anticoagulants cannot be given or if it is not effective.
• Surgery is rarely indicated when anticoagulants are contraindicated or are ineffective.

Dr. Maya Patel

She is a renowned neurologist, illuminates the path to optimal brain health. Her expert insights guide individuals to understand and nurture their brain, ensuring mental clarity, resilience, and well-being.