Venous Thromboembolism (VTE)

What is Venous Thromboembolism (VTE) and what are my risks?

This is when blood clots form in the veins of the lower limb and the calf leading to a deep vein thrombosis or DVT. The clots can break off and travel to the lungs causing a pulmonary embolism or PE. The muscles of the calf act as a pump to move the blood around and back up towards the heart. Lack of mobility during the anaesthesia or following surgery on your leg together with the use of a plaster cast will result in the blood flow through the veins to reduce and puts you at risk of VTE. Fortunately, in most foot and ankle operations the duration of surgery is short, and patients are sometimes even allowed to weight bear on the operated foot. The rates of VTE in foot or ankle surgery is low and has been found to be less than 1%.

What happens if I develop VTE?

A large proportion of patients with a DVT are asymptomatic, which means they will not know that they have a blood clot and will not be affected. However, in a proportion, calf pain, redness or swelling may occur. With treatment and over time the clots dissolve and flow return to normal however some patients may develop ongoing pain and disability and a condition referred to as post thrombotic syndrome (PTS). A more serious consequence of a DVT is the development of a pulmonary embolism (PE) that may present with chest pain, shortness of breath and with secondary pressure on the heart it can even lead to death. Fortunately, the rates of a fatal PE in patients undergoing foot and ankle surgery is extremely low.

What is VTE prophylaxis and what medications is used to thin the blood?

VTE prophylaxis is the measures taken to prevent blood clot formation. These include simple measures such as early mobilisation of patients after surgery, regular foot and ankle exercises as well as the use of stockings or foot pumps. Some medications can be used to thin the blood in cases where the risks of VTE are high and outweigh the risk of side effects from these medications. Low molecular weight heparin (LMWH) is the most used preparation, this is administered daily and by injection under the skin. It is usually done by the patients themselves at the same time of the day, every day for several days or weeks after their surgery.

What can I do to I reduce my risk of developing VTE?

• It is particularly important to avoid long periods of immobility in bed or a chair. We advise regular ankle and foot exercises especially in the first 14 days after your surgery. Although elevation of the post-surgical limb is important to reduce the swelling, this should not mean long periods in bed or confined to a chair. As a rule of thumb, we recommend 20 minutes of exercises in every hour during the waking hours of the day. If you can weight bear, then you must spend time walking around to stimulate the blood flow in you calves. 
• You must also keep well hydrated drinking adequate amounts of water.  You should avoid large volumes of alcohol which can make you dehydrated.
• The use of flight socks or TED stockings are also advised. This can be worn on the non-operated leg but also consider wearing on the operated side if the dressings or swelling allow. Please discuss this with your admitting nurse or with you surgeon.
• If you take the oral contraceptive pill or are on Hormone replacement therapy, then we advise that you stop taking these medications for 4 weeks prior to your surgery and not to restart before 2 weeks following the surgery. Please discuss this with your doctor or with your gynaecologist prior to discontinuing your medication so that alternative forms of treatment or contraception can be provided if necessary. 

What are the signs and symptoms of deep vein thrombosis (DVT) and pulmonary embolism (PE)?

Deep vein thrombosis:

• Calf pain or swelling
• One sided or unilateral Ankle swelling
• Redness, erythema or discolouration of the foot or ankle

Pulmonary Embolism:

• Chest pain
• Shortness of breath or increase breathing rate
• Palpitations or fast heartbeat
• Chest pains on breathing in
• Cough that maybe associated with pink or blood-stained sputum
• Anxiety and/or sweating

What should I do if I think I have developed a DVT or am suffering from PE?

If you develop signs of DVT or PE, you will need to seek medical attention immediately so that the diagnosis is confirmed, and treatment started on the same day. If this is during working hours you may want to contact your doctor or surgeon for advice, if this is not possible then we recommend presenting to the closest emergency department and informing them that you suspect a VTE complication of your surgery.

What you need to know about your LMWH injections? Including its side effects and what to do if you develop them?

Low molecular weight heparin (LMWH) is the most prescribed medication in use for the prevention of post-operative VTE in the UK. Unfortunately, these are only available as injections and are not without side effects. Some of the side effects can cause significant morbidity and as such careful selection and risk assessment is important. We do not routinely prescribe these and will weigh up your individual risk against the risk of side effects from these medications. Some of which are detailed below:

• Local bleeding and wound complications
• Bleeding from other sites including but not limited to bowel, bladder and the brain
• Heparin induced Thrombocytopenia (HIT) – a rare but potentially devastating complication of heparin medications. An abnormal antibody response that attacks the patient’s platelets and lowers the count. This may lead to activation of the platelets and formation of multiple blood clots. Therefore, the heparin treatment can paradoxically lead to widespread blood clot formation that can lead to organ failure and in rare circumstances even death.

What are the risk factors for thrombosis?

We will consider your individual risks of thrombosis against the risks of side effects of LMWH before prescribing these medications. 

The following will put you at a strong risk for developing VTE:

• A history of previous VTE, or recurrent miscarriages or a family history of VTE in a first degree relative
• A diagnosis of thrombophilia (tendency of blood to clot easily) such as Factor V Leiden deficiency or Antiphospholipid syndrome.

Other risk factors include:

• Advancing age GREATER than 60 years old
• Significant medical co-morbidity
• Smoking
• Use of the contraceptive pill or hormone therapy (HRT)
• Obesity with a BMI GREATER than 30.
• Varicose veins
• Post-partum period (6 weeks)
• Active cancer or cancer treatment

Please inform your surgeon immediately if you feel you may have any of these risk factors and to discuss your VTE risks and prevention strategy.