March is national Deep Vein Thrombosis Month (DVT), an initiative to raise awareness of this common and potentially fatal condition. When recognised early, DVT can be treated before it has fatal consequences and this campaign aims to help prevent, recognise, and treat DVT and save lives.
Essentially, a DVT is a blood clot (thrombus) on the inside of a vein. Commonly, this forms in the leg, and often results in a partial or complete blockage of the circulation. Clots arising in the lower leg are unlikely to cause serious complications, but those above the knee can break off and lodge in a lung vessel (pulmonary embolism). When this happens, the circulation to the lungs can be blocked, sometimes fatally. Both DVT and pulmonary embolism require urgent investigation and treatment. Together, these conditions are known as venous thromboembolism (VTE).
Sometimes a DVT can be ‘silent’ with no symptoms. However, more commonly a DVT in the leg causes swelling, pain, discoloration or abnormally hot skin over the affected area. Similar signs can be the result of muscle strains, phlebitis (inflammation of a blood vessel), or skin infections, and it is therefore important that medical professionals are alert to the potential for DVT and can distinguish between these various conditions.
If a DVT is suspected, an ultrasound scan of the affected vessel is often the most sensitive method of making a definitive diagnosis. A D-Dimer blood test can also indicate whether blood clots are present in the blood stream. A raised D-Dimer is a reliable indicator of blood clotting, but as it takes a while for these proteins to build up in the blood, the level is not always immediately raised. It can also be raised for instance after surgery or trauma, and so does not always indicate a DVT or PE.
Anyone can develop a DVT but risk factors include recent surgery, immobility, obesity, smoking, some birth control tablets, and pregnancy. There is evidence that people on long haul flights may be more at risk. The risk increases with age. It is a very rare condition in children but in adults, around 1 in 1000 people are affected.
Some people are at a generally low risk, and there is no need to take routine preventative measures. For pregnant women, unless there are existing additional risk factors, ‘watchful waiting’ has been found to be of greater benefit than taking prophylactic medications, which may harm the foetus. It has been shown that for travellers, compression stockings have reduced the occurrence of DVT significantly. Patients who have had previous VTEs may be advised to take long term anticlotting medication. In the longer term, cessation of smoking and weight loss are also of benefit.
Patients who are in hospital should be assessed for their risk, and a VTE risk assessment chart is now routine for most surgical admissions. Depending on the reason for admission, heparin products, compression stockings, early mobilisation after surgery and pneumatic boots have all been shown to be of benefit, and should be used according to the risk as assessed prior to admission.
Once a clot has developed, it is often not amenable to anticoagulation drugs. However, patients are normally given anticoagulants to prevent further clots. They may remain on a course of these drugs for several months following diagnosis.
Thrombolytic drugs can be given to help break the DVT down. There are some additional risks with both anticoagulants and thrombolytic drugs, as the blood is thinned significantly. If a patient is already prone to bleeding, this can cause additional risk, and again the clinician will need to carefully assess whether the risk of increased bleeding may outweigh the benefit of breaking down the clot.
In patients that are at high risk of a pulmonary embolus, an Inferior Vena Cava filter can be inserted. This is a mechanical filter that can catch any clot that breaks off before it reaches the lungs. The surgery is invasive and would generally only be used for patients who have a DVT, and cannot be given antithrombotic medication. Once they can be given medication, the filter should be removed.
In certain circumstances, the clot can be surgically removed, although again this is an invasive procedure which in many cases is not necessary.
We deal with a number of DVT and VTE related claims each year. As highlighted above, it is important that patients undergo a thorough risk assessment, particularly before surgery, and appropriate measures are put in place to prevent DVTs (and PEs) from developing. If a DVT or PE is suspected, then it should be acted upon immediately, and appropriate referrals put in place. Investigations should include ultrasound and blood tests, and if necessary these should be repeated in an acute situation where the blood proteins may be subject to change. A rapid assessment of whether thrombolytic drugs or further anticoagulants are required should be undertaken. Again, the risks and benefits of treatments need to be carefully weighed up.
Philippa Luscombe, a partner in the clinical negligence team at Penningtons Manches, commented: “Deep Vein Thrombosis Month gives us an opportunity to increase awareness of this potentially fatal condition, and with rapid advances in social media, information can reach a large number of people quickly and simply. If we are all more alert to the seriousness of the condition, hopefully some cases may be prevented or treated more effectively.”