Diagnosing and treating deep vein thrombosis and pulmonary embolism
We spoke to Dr Prahlad Ho, Director of Haematology at Northern Health, and inaugural Director of Northern Pathology Victoria, to discuss the risk factors, diagnosis and treatment of deep vein thrombosis and pulmonary embolism.
Deep vein thrombosis (DVT) is a blood clot that forms in a vein, typically in a leg. If not treated, it may dislodge and travel into the lungs. That process is called a pulmonary embolism (PE), which can be fatal. The most common provoking causes of DVT and PE include surgery, injuries and long-distance travel - typically greater than 4-6 hours.
Dr Ho said,
“DVT and PE affects about 1 per 1000 residents in Australia and is more common after injuries, surgery, pregnancy and hospitalisation, though there is a large variation in this. The common risk factors include male gender, age (over 65 years of age), and obesity.
“Another risk factor is thrombophilia, an inherited abnormality of blood coagulation that can increase the risk of thrombosis. Varieties of thrombophilia include Factor V Leiden mutation, prothrombin gene mutation, Protein C deficiency, Protein S deficiency and Anti-thrombin III deficiency. Some of these abnormalities, such as Factor V Leiden and prothrombin gene mutations, are quite common in the population and do not typically predict the risk of thrombosis in the general community. Careful consideration is therefore required for each individual, and it is important to discuss this with your doctor.
“Other risk factors include antiphospholipid syndrome, which can be acquired at any time of your life. In addition, cancer may also contribute to DVT and PE, and in certain situations, we may test you for this. However, one-third of all DVT or PE cases occur with no apparent cause.”
DVT is normally characterised by pain and swelling in one leg, usually in the calf or thigh. Typically, the affected leg is significantly bigger and redder than the other leg. However, it is important to note that not all leg swelling is associated with DVT. If DVT is suspected, it is important that a diagnosis is made as quickly as possible, as the potential for the clot to cause a pulmonary embolism by travelling to the lungs is a major concern.
Pulmonary embolism is characterised by sharp chest pain and shortness of breath and can sometimes be difficult to differentiate from a heart attack. There is, however, a large spectrum of symptoms, and people with no visible symptoms might be diagnosed by low oxygen levels.
“Typically the diagnosis of DVT is through using a Doppler Ultrasound, which is a quick, painless way to check for problems with blood flow. Diagnosis of a PE is typically through CT scan. A blood test called a D-dimer, which measures the breakdown of clotting factors, can be also useful to predict the presence of a DVT or PE. This is sometimes used in some situations by your doctor, though the final diagnosis must be made using scans.”
“Pathology is crucial in the management of DVT and PE for a number of major reasons, including assisting with diagnosis; evaluating the underlying risk factors for the clot formation, including thrombophilia and antiphospholipid screen; as well as evaluating baseline bloods, particularly kidney and liver functions, to ensure the safety of using blood thinners. In patients using warfarin therapy, regular monitoring using a blood test called International Normalised Ratio (INR) is required every 1-4 weeks.
"The main treatment for DVT and PE is with anticoagulant medications – or 'blood thinners' – for a period of 3-6 months, although sometimes they may be prescribed long-term. There are two major groups of long-term blood thinners, these being the Direct Oral Anticoagulants (DOAC), and warfarin. The DOACs have been only recently available over the last five years and are more convenient than warfarin as they do not require regular blood tests. However, some conditions are not suited for the new DOAC therapy, in which case warfarin remains the preferred option. Certain types of anticoagulation injections may also be used for an inpatient.
“Other therapies in a small subpopulation of patients may include thrombolysis (“clot-busting agents”), or surgical intervention, such as endovascular procedures.” said Doctor Ho.
When taking blood thinners or clot-busting isn't possible or is not working well, your doctor may want to try a more involved procedure such as surgery, to insert a small filter in the vein or to remove a deep vein clot.
Measures can be taken to prevent DVT, including
- Avoiding sitting still and trying to move as much as possible, especially following surgery or during long-distance travel;
- Changes in lifestyle, including losing weight and quitting smoking;
- Regular exercise.
It is important that anyone experiencing symptoms of DVT contact their doctor. Immediate medical attention should be sought if any signs or symptoms of a pulmonary embolism are present, such as sudden shortness of breath; chest pain; feeling lightheaded or dizzy; rapid pulse; or coughing up blood.
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This article appeared in the December 2018 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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