Veins can be thought of as the ‘return’ side of the circulation pathway. Their job is to return blood flow from the organs and limbs back to the heart.

Within the venous system there are superficial veins and deep veins. The deep veins are blood vessels that lie deeper within the muscles and are responsible for about 90% of the drainage of blood from the legs. 

When a blood clot forms inside the deep vein blood vessel, it is called a deep vein thrombosis (DVT). A DVT can cause damage to the deep veins but the bigger worry is if some of the blood clot dislodges and travels to other parts of the body thereby restricting blood flow to the affected area.

The below are risk factors for deep vein thrombosis:

• Obesity
• Smoking
• Age over 50 years old
• Prior history of DVT
• Family history of DVT
• Having a thrombophilia (condition that makes you more likely to clot)
• Having varicose veins (chronic venous insufficiency)
• Having phlebitis (clots in your surface veins)
• Surgical procedures (especially orthopaedic)
• Being very unwell with other illness
• The risk of deep vein thrombosis in pregnancy is increased. Pregnant women have a 1-2 chance in 1000 of developing a DVT.
• Being immobile for long periods due to injury, illness or travel
• Being on hormone replacement therapy (HRT) or the oral contraceptive pill (birth control pills)
• Having cancer carries a higher risk

A deep vein thrombosis may be entirely asymptomatic, or it may cause symptoms including: pain in the lower leg or calf muscle, redness or warmth in the calf, and lower leg swelling.

If a DVT blood clot travels to the lungs it can cause a pulmonary embolism. This serious condition can also be asymptomatic, or it may cause symptoms such as chest pain or tightness, a cough, coughing of blood, and feeling short of breath. A pulmonary embolism requires urgent medical attention as more severe cases may be fatal.

A blood test called a d-dimer can screen for the presence of a DVT. This blood test does not make a definitive diagnosis though, it just indicates a likelihood of the diagnosis. If the result is negative then you can be assured you don’t have a DVT, if the result is positive, then you need an ultrasound to confirm the diagnosis.

The diagnosis of DVT is made by doppler ultrasound at Palm Clinic in Auckland, NZ. The ultrasound can visualise the deep veins and see if there is any thrombus (clot) inside.

Given that the symptoms and signs can be mild, it is important to have a high index of suspicion and a low threshold for ultrasound checks. Given the risk of serious complications such as a pulmonary embolism, it is better to be safe than sorry.

If a pulmonary embolism is in question, you will be referred to the hospital for a CT scan called a CTPA (CT Pulmonary Angiogram), which specifically looks at the lungs.

Treatment at Palm Clinic in Auckland, NZ is aimed at minimising the chance of the clot growing and/or moving to other parts of the body. Treatment can vary depending on the size and position of the clot.

Treatment options are:

• Medications
• Anticoagulants: These are blood thinners which affect the blood’s natural ability to clot. They can stop an existing clot from getting bigger and thereby reduce the risk of it breaking off and travelling to other parts of the body.
• Thrombolytic drugs: Less commonly, thrombolytic drugs are used to help dissolve the DVT. These can have serious side effects such as severe bleeding, and so are only ever used when the benefits outweigh the risks. These are only given in a hospital setting.
• Compression stockings: Compression stockings provide external support to the lower leg, which improves flow within the deep veins. The better the flow, the less the chance of a blood clot increasing in size and the less retention of fluid in the tissues. At Palm Clinic in Auckland, NZ we can fit you for the appropriate compression stockings. Wearing compression stockings for two years after the diagnosis of a DVT reduces the chance of developing post thrombotic syndrome (discussed below).

Prevention involves addressing the risk factors mentioned above. These include quitting smoking, attaining a healthy body weight and staying active and avoiding prolonged immobility.

For those who are prone to DVT for medical reasons, a prophylactic dose of anticoagulant medicine may be indicated. Other factors that reduce the risk of DVT are wearing compression stockings on the lower extremity when you expect to be immobile or have had a procedure.

Treatment of varicose veins will also reduce your risk of DVT in the long term as the presence of varicose veins carries a risk of DVT. After an initial DVT has resolved we will usually recommend having your varicose veins treated to lessen your long term risk of future DVTs.

Potential complications of having a deep vein thrombosis are failure of either the surface veins (chronic venous insufficiency or varicose veins) or deep veins (post thrombotic syndrome). Symptoms of either can include aching, swelling, and pigmentation of the lower legs.

If some of the DVT clot breaks off and travels it can block circulation to the organ that it arrives and stops at. The most likely organ to be affected is the lungs – this is known as a pulmonary embolism and can result in heart failure and/or be fatal.

A deep vein thrombosis is often not visible however it can cause leg swelling and varicose veins, pictured below.