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Deep Vein Thrombosis (DVT)

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Deep vein thrombosis is the formation of a blood clot or thrombosis within the deep vein system predominantly in the legs. Deep veins pass through the legs and are surrounded by the muscle layers. Blood flow in deep veins of the legs requires some mechanical pump assistance to return to the heart, this is provided by the calf muscles contracting which compress the veins and pushes the blood upwards. Valves within the veins open and close with this pump action to keep the blood flow going in the upward direction and stop backflow. Anything that slows or allows pooling of the flow through the deep vein system can cause a DVT.

This includes long periods of sitting or lying during air or car travel, major surgery, or injury. There are also some genetic factors that can cause your blood to clot more easily that can increase the risk of DVT. Anyone can develop a DVT but the risks are increased with any of the incidences listed below; 

Increased Risk factors

  • Hospitalisation for illness or major surgery
  • Injury
  • Pregnancy and first 6 weeks post delivery
  • Hormone replacement therapy or high dose oral contraceptive pill
  • Prolonged sitting of up to 6-8 hours
  • History of active cancer and concurrent cancer treatment
  • Family history of DVT, or previous DVT
  • Smoking

Signs and Symptoms

  • Swelling in the lower affected limb
  • Pain and tenderness in the affected limb
  • A change in the colour of the skin on the affected limb for example redness and warmness


  • Anticoagulant medications including heparin and warfarin are the standard treatment for DVT. These stop the blood forming clots so easily, and stop old clots from becoming bigger.
  • Venous ultrasound to locate the clot
  • Severe case may require the use of thrombolytic medications
  • Compression stockings may need to be worn to reduce the pain and swelling and help prevent post-thrombotic syndrome when vein valves have been affected
  • Some clots may form in the superficial vein system but these are not as serious as within the deep vein system

Complications of DVT

If the DVT remains in the leg it can cause inflammation (phlebitis) and leg ulcers and long term damage to the valves in the veins as it progresses up the vein.

The real danger of DVT’s is that it may leave the vein and travel up into the circulatory system where it may become lodged in the main artery or one of the branches of the lung. This may cause difficulty breathing, rapid breathing, and chest pain on inspiration. Severe cases can lead to collapse or sudden death.

If you think you have any of these symptoms call 000 immediately for assistance or proceed straight to the emergency department of your hospital.