Deep vein thrombosis (DVT) is a type of venous thrombosis in which a blood clot forms in a deep vein most commonly in the legs or pelvis. DVT, less commonly can also occur in the arms, the mesenteric and cerebral veins.

This happens when a deep vein becomes damaged or if the blood flow within a deep vein slows down or stops, which encourages the formation of clots.

Deep venous thrombosis (DVT) is the third most common cardiovascular disease. Two-thirds of patients are first-timers, and the rest are recurrences.

Several risk factors make you prone to developing DVT. The two most common are an injury to your lower body and surgery that involves your hips or legs.

In most cases, DVT does not show any noticeable symptoms, which makes it difficult to detect. When symptoms do occur, they can include pain, swelling, redness, and enlarged veins in the affected limb.

DVT can have serious complications. The most common life-threatening danger is pulmonary embolism (PE). PE develops when the blood clot breaks free from the wall of the veins, travels as an embolus to the right side of the heart, and gets lodged in the pulmonary artery that supplies blood to the lungs. An embolus in the pulmonary vein almost most certainly leads to death, if not treated promptly.

Even if the blood clot does not break free and cause embolism, it can permanently damage the valves in the vein of the legs. This can lead to pain, swelling, and leg sores in the affected leg.

DVT is venous thromboembolism disorder and is the third most common cause of death from cardiovascular disease after heart attacks and stroke. Even in patients who do not get pulmonary embolism, recurrent thrombosis is a major cause of morbidity.

DVT should be treated promptly to prevent its serious complications. Treatments include medicines for a few months, wearing compression stockings for two years, and surgery.

Your doctor will take preventive measures if you have undergone surgery in the lower part of your body, including total hip or total knee replacement.

Causes and risk factors

Several factors can adversely affect blood flow in the deep veins and increase the risk of developing blood clots. These include:

  • Increasing age. More common after the age of 40 years
  • Having an inherited condition that increases your risk of blood clots
  • Having cancer
  • Some cancer treatments like chemotherapy
  • Having a history of DVT
  • Having a family history of DVT
  • Injury to vein due to fractures, severe muscle injury, or major surgery especially involving the abdomen, pelvis, hip, or lower limbs. A fractured hip or leg, or a major surgery on your hip, knee, or lower leg can disrupt normal blood flow. At such times, blood clots in the veins develop due to impaired blood flow, hypercoagulation, and damage to the veins.
  • Having restricted blood flow in a deep vein due to injury or surgery
  • Paralysis
  • Prolonged immobilization like sitting for extended periods such as on long trips in a car, bus, train, or airplane
  • Prolonged confinement to bed after surgery or a serious injury
  • Being pregnant or having recently delivered a baby
  • Being overweight or obese
  • Having an autoimmune disease, like lupus or inflammatory bowel disease
  • Having varicose veins
  • Increased estrogen levels caused by birth control pills, hormone replacement therapy, during pregnancy, and for up to 3 months after giving birth
  • Having a pacemaker
  • Having COVID-19

What are the symptoms of DVT?

Up to 30%of people with a DVT don’t have symptoms and some people experience very mild symptoms, which may not raise concern. A DVT usually forms in the veins of your legs or arms. The symptoms associated with acute DVT include:

  • Swelling of your leg or arm, which can sometimes develop suddenly.
  • Pain or tenderness in your leg or arm on standing or walking.
  • The swollen area may be warmer to the touch than usual.
  • The skin over the affected area becomes red or discolored.
  • The veins below the skin over the affected area become engorged
  • Abdominal pain or flank pain when the mesenteric veins are affected
  • Severe headaches of sudden onset and seizures when blood clots affect the cerebral veins.

A pulmonary embolism develops when the clot moves from the vein of the leg or arm and travels to the lung. This is a very serious condition and should be promptly treated.

Symptoms of acute PE include:

  • chest pain
  • shortness of breath
  • hemoptysis (cough with blood)
  • lightheadedness, and
  • fainting.


Complications from DVT can be very serious, even fatal. They can include pulmonary embolism (PE), chronic venous insufficiency, and post-thrombotic syndrome.

Pulmonary Embolism (PE)

A pulmonary embolism, as mentioned above, develops when the blood clot breaks free from the affected vein travels toward the heart, proceeds through the right part of the heart, and gets lodged in the pulmonary artery in the lungs.

The timeline for this differs. It can happen immediately after the formation of the blood clot or it can happen after days. Once it gets lodged in the pulmonary artery, it can block the blood flow to the lungs and heart.

Due to obstruction of the pulmonary vascular bed, PE can cause acute right ventricular failure, which can be fatal. Most patients with PE die within the first hours of its development.

Chronic venous insufficiency

In chronic venous insufficiency, the affected vein no longer functions properly. It’s a long-term condition where blood stagnates in the vein instead of flowing back to the heart. Pain and swelling in the leg are the common symptoms of this condition.

Post-thrombotic syndrome

Some people with DVT develop a condition called post-thrombotic syndrome. Post-thrombotic syndrome results in venous hypertension due to damage to the involved vein.

This increased pressure in the vein can damage the valves that are responsible for venous blood flow upwards toward the heart. Valve damage results in blood pooling in the vein and this can be long-lasting.

Patients with post-thrombotic syndrome may experience symptoms of pain, swelling, skin changes, the development of new varicose veins or spider veins, and leg sores.

How is DVT diagnosed?

Your healthcare provider will take your medical history to find out whether you have had a fracture or surgery. He will then do a physical examination to look for signs of DVT.

Duplex venous ultrasound.

This is the standard imaging test to diagnose DVT. It uses two types of ultrasound techniques to create images or videos of the veins and the blood flowing through them. The Doppler ultrasound shows how the blood flows in vessels, and the real-time ultrasound imaging displays the vein’s anatomy, which reveals blockages, if present.

If the results of the duplex ultrasound are not satisfactory, your health provider may ask for further tests.


This is an invasive test, in which your provider uses a catheter to inject a special dye (contrast material) into your veins to see if any blood clots are blocking blood flow inside your veins. Venography is rarely used nowadays.

Computed tomography (CT) scan

CT scan is a type of X-ray that shows images of the structures inside your body. It helps to find a DVT in your abdomen, pelvis, or brain, as well as blood clots in your lung (pulmonary embolism).

Magnetic Resonance Imaging (MRI) or Magnetic Resonance Venography (MRV)

MRI shows images of the structures inside your body. Magnetic resonance venography is a non-invasive diagnostic imaging procedure that creates detailed images of the veins

MRV shows pictures of the veins in specific locations in your body. MRI and MRV can offer more information than a duplex ultrasound or CT scan.

D-dimer blood test

A D-dimer blood test measures the amount of D-dimer, a protein your body makes to break down blood clots. A negative D-dimer test means that the patient probably does not have a blood clot.

Management and treatment of DVT

A blood specialist called a hematologist treats DVT if you keep getting DVT or if you have a blood clotting disorder. A vascular surgeon may be asked to treat you if you need surgery to get rid of a blood clot.

The aim of DVT treatment is threefold:
  • Prevent the clot from increasing in size.
  • Prevent the clot from dislodging and traveling to the lungs.
  • Prevent the development of another DVT.

DVT treatment options include:


These medicines are also called blood thinners. They help to reduce the risk of developing more clots and prevent existing blood clots from getting bigger. They can be given orally or by intravenous route. Your healthcare provider will prescribe them for three months or longer. They can have serious side effects and therefore, take them as prescribed.

Clot busters (thrombolytics)

Your healthcare provider will prescribe these drugs for more serious cases of DVT or if pulmonary embolism has developed, or if other medications aren’t working. Thrombolytics are given through an IV in your arm or a catheter placed directly into the clot. They can cause serious bleeding.


If for some reason, you can’t take medicines to thin your blood, a filter may be placed into the inferior vena cava in your abdomen. This vena cava filter aims to trap the clots and prevent them from traveling to the lungs.

Support stockings (compression stockings)

You have to wear these stockings on your feet. They extend to the level of your knees. These are special knee socks that help prevent blood from pooling in the legs. They also help to reduce swelling in the legs. For DVT, you will be advised to wear these stockings during the day for a few years.

General activity guidelines

  • If your legs are swollen, lie in bed with your heels resting on some platform and raised about 5 to 6 inches. This will help improve circulation and decrease swelling.
  • If you sit for long periods as during a long flight or road trip, exercise your calf muscles, stand up, and walk for a few minutes every hour.
  • Avoid activities that may cause serious injury.
  • Stay well hydrated.