Overview Symptoms Complications Treatment</aDiagnosis

Deep Vein Thrombosis (DVT)

What is Deep Vein Thrombosis (DVT)?

DVT is the formation of a blood clot (thrombus) within the deep veins. The most common site for their formation is the legs thought it could take place in any vein of the body.

How does it present?

  • Leg swelling mainly on one side. Both legs may be involved in the main vein in the abdomen is blocked. (Picture 1)
  • Pain in the leg which may be soreness or cramp-like.
  • A patient may be totally asymptomatic
Swelling of the right leg
Picture 1 – Swelling of the right leg

Is DVT a matter of concern?
Most patients are not aware of having this problem. DVT itself is not life-threatening but the leg clots may break and pass via the blood to the lungs where they may cause blockage of the vessels causing acute lung failure. This is a life-threatening condition. Should one become breathless with leg swelling one should go to the casualty to exclude pulmonary embolism? (picture 2)

Pulmonary embolism
Picture 2 – Pulmonary embolism

What are the warning signs of Pulmonary Embolism (PE)?

  • Unexplained sudden onset of shortness of breath.
  • Chest pain or discomfort that worsens when you take a deep breath or cough.
  • Lightheadedness, fainting or dizziness.
  • Rapid pulse
  • Coughing up blood

Why does it happen?
These clots in the deep veins form due to any reason that prevents your blood from circulating properly or there is a breakdown in the cotting mechanism of the blood.
Who is more prone?
There are many factors that increase the risk of developing DVT and the more the factors you possess the higher the risk.

  • Inheriting a blood clotting disorder – Many people possess the factors that can cause DVT but mostly they are asymptomatic with normal clotting of blood until it is combined with another risk factor.
  • Prolonged bed rest like prolonged hospital stay or paralysis. In both these conditions the calf muscles, which are also called external hearts, as they pump the blood back to the heart against gravity. When there is no movement as in paralysis or prolonged hospital admission there is a very high chance of developing DVT.
  • Injury or surgery – Injury to the veins during an accident or surgery increases the chances of blood clot formation.
  • Pregnancy – This compresses the pelvic veins causing stagnation of the venous blood in the legs. Women with inherited clotting disorders are at increased risk. This risk continues for 6 weeks after delivery.
  • Birth control pills or hormone replacement therapy – they both increase your blood ability to form clots.
  • Obesity – this increases the pressure on the pelvic veins and limb veins.
  • Smoking – Affects blood clotting and circulation with an increased risk of DVT.
  • Cancer – some cancers increase certain substances in the blood that cause clot formation. Some types of cancer treatment also increase the risk of blood clot formation.
  • Heart failure –these patients have a greater risk of DVT. In such patients, even a small PE is very noticeable.
  • Inflammatory bowel disease – Crohn’s and ulcerative colitis increase the risk.
  • A family or personal history of DVT or PE increase the risk.
  • Age – over 60 increases the risk though no age is immune.
  • Sitting for long periods like driving or flying – The calf muscles stay stagnant for long promoting blood clot formation in the sinuses oft he calf muscles.

What are the complications of DVT?

The two major complications or DVT are:
1. Pulmonary Embolism (PE) which increases the mortality
2. A post-phlebitic syndrome which increases the morbidity.

Why is pulmonary embolism such a lethal problem?

In PE clots travel tot he lungs and block its blood supply. The patients present with:

  • Unexplained sudden shortness of breath
  • Chest pain or discomfort worse on taking deep breath or coughing
  • Feeling light-headed or dizzy
  • Rapid pulse
  • Coughing blood.

What is post-phlebitic syndrome?

It is a common complication of DVT and is a collection of symptoms. It takes place many years later. The common complaints are:

  • Leg swelling
  • Leg pain
  • Leg discolouration
  • Leg ulcers.
Post Phlebitic Syndrome
Picture 3 – Post Phlebitic Syndrome

There is damage to the vein from blood clots reducing the flow in the affected areas.

How is the condition diagnosed?

  • History and examination are fairly conclusive in most cases helping us to reach a provisional diagnosis.
  • Colour Doppler study – This shows dilated veins with a sluggish flow or no flow. You can see a blood clot making the veins not compressible.(Picture 4)


Clot seen in the vein
Picture 4 –Clot is seen in the vein
  • Blood tests – Most routine tests are normal but the D-dimer is elevated. D-dimer is a clot-dissolving substance.
  • Venography – The dye is injected into the foot vein and images of the dye in the veins of the leg are recorded. A filling defect denotes the occluded vein. (Picture 5)
venography showing clot in the vein
Picture 5 – venography showing clot in the vein
  • CT or MRI scans – show the clots in the veins. (Picture 6)
DVT on MRI and colour Doppler (B)
Picture 6 – DVT on MRI and colour Doppler (B)

What are the aims of the treatment?

  • Preventing clot from increasing in size
  • Preventing clot from breaking loose and causing PE
  • Reducing your chances of having DVT again.

How is it treated?

This includes:

  • Leg elevation at night. (Picture 7)
  • Mid-thigh stockings during the day. (Picture 8) These stockings are put for 2-3 years.
  • Anticoagulation for clot dissolution and prevention of Pulmonary embolism.
leg elevation
Picture 7 – leg elevation
mid thigh stocking

Picture 8 – mid-thigh stocking

What are blood thinners?

These are drugs that reduce the ability of the blood to clot. They cannot dissolve the existing organized clot but they prevent a fresh clot from forming and thus reduce the chances of old from extending.

How are blood thinners given?

The first injection of heparin is given for a few days. This is a Low Molecular Weight Heparin (LMWH) followed by oral drugs (Warfarin or Xarelto). These blood thinners are given for at least 3 months. They have serious side effects if the dose becomes excessive and therefore they have to be regularly monitored by blood tests.

What are the side effects of these blood thinners?

Bleeding which can be involving any organ of the body.

  • Brain – stroke
  • Skin – Bruising
  • Kidneys – bleeding with urine.

How can I be careful?

  • Watch for bleeding from the gums while brushing your teeth daily
  • Watch for bruising with a minor injury
  • Watch for bleeding in the urine
  • Do regular blood tests as prescribed by your doctor.
  • Avoid blood thinners during pregnancy

Is there any other way to dissolve clots?

There are clot-busters (Thrombolysis) that act fast and immediately but are very dangerous and can cause serious extensive bleeding which could be life threating and so have to be given with a lot of caution. They are administered only in if all other treatment options have failed.
They are given intravenous or directly within the clot. It has to be administered in the ICU.

How can clots be prevented from going to the lungs?
This is achieved by introducing IVC filters which are introduced from the groin and placed in the large vein in the abdomen just below the kidneys. These veins take the blood back to the heart and then go to the lungs. (Picture 9)


IVC filter
Picture 9 – IVC filter

What is your routine lifestyle once you are on long term blood thinners?

  • Watch for any signs of bleeding.
  • Regular blood tests as prescribed by your doctor.
  • Take your medication without fail in the same dose as prescribed by your doctor. It is generally once a day dose and should be taken for over 3-6 months and only stopped once your colour doppler study shows no clots in the veins.
  • Alcohol a green leafy vegetables (Contain Vitamin K) have to be avoided. Consult your doctor.
  • Physical activity is a must which prevents more clots from forming. After about 10 days clots organise and there is a very small possibility of them detaching and passing to the lungs.
  • Wear stockings regularly during the day and elevate your legs at night.

How can I prevent DVT?

1. Avoid sitting still by:

  • Move your legs in bed even if you have had surgery. Your doctor will try to mobilise you as soon as it is safe.
  • Avoid sitting cross-legged as it limits blood flow.
  • During long travel walk regularly by stopping the car every hour and taking a little walk or walking on the aisle during the long flight.
  • If waking is not possible then move your ankles regularly by raising your heels with toes fixed on the ground and then raise your toes with your heel stuck tot he ground.

2. Make lifestyle changes – lose weight, quit smoking as they enhance the chances of having DVT.

3. Regular exercises – This is very essential to reduce the risk of developing DVT in those who sit long hours during work or frequent travel. (Picture 10)


regularly daily exercise
Picture 10 – regularly daily exercise