How dangerous are venous blood clots and how can they be avoided?

Posted: 29/10/2024

Put simply, blood clots can be fatal. It is estimated that approximately 30,000 deaths occur in the UK each year from people suffering fatal blood clots in the veins, the medical term for which is venous thromboembolism (VTE). 

Venous thrombosis is the blockage of a vein caused by a thrombus. A common form of venous thrombosis is deep vein thrombosis (DVT), when a blood clot forms in the deep veins. If a thrombus breaks off, flows to the lungs, and lodges there, it becomes a pulmonary embolism (PE), a blood clot in the lungs. About 25% of people who have a PE will die suddenly and without warning symptoms. About 23% of people with a PE will die within three months of diagnosis. Just over 30% will die after six months, and there is a 37% mortality (death) rate at one year after being diagnosed.

VTE can affect men and women of all ages, races, and ethnicities. People at the highest risk include those with cancer, those having surgery, or anyone with major trauma such as fractures or immobilisation. Long-haul flights can increase the risk of developing a DVT, due to the period of immobility. The risk of DVT increases with the length of the flight and is particularly high for flights that are 8 to 10 hours or longer.

Symptoms of a VTE include throbbing or cramping pain, swelling, redness and warmth in a leg or arm, sudden breathlessness, sharp chest pain (may be worse when breathing in), and a cough or coughing up blood. Other factors that increase the risk of VTE include having had a previous VTE, being obese, having a family history of VTE, being a smoker, and some chronic health problems. 

Venous thromboembolism and negligence

Patients falling into these categories should receive preventative measures before undergoing surgery to reduce the risk of VTE occurring. Failure to perform a risk assessment and to provide appropriate venous thromboprophylaxis in surgical patients is considered negligent. Clinicians looking after all hospitalised patients who are not assessing their patients' risk for VTE and/or not providing appropriate prophylaxis are at risk of being held negligent. 

A pre-surgical risk assessment should include consideration of several factors. Firstly, if there is the option to perform surgery under local or regional anaesthetic, rather than general anaesthetic, this reduces the risk of VTE. Mechanical prophylaxis, such as anti-embolism stockings or intermittent pneumatic compression (IPC), is appropriate and reduces risk for patients undergoing certain types of surgery, so long as those patients are educated to use them properly. 

Similarly, some surgical patients can receive pharmacological prophylaxis, such as blood-thinning medications, and some can be encouraged to mobilise as soon as possible after surgery to limit the period of immobilisation when VTE can occur. Blood thinners keep blood clots from getting larger and stop new clots from forming. Conventional blood thinners include warfarin and heparin, but newer blood-thinning medicines called direct oral anticoagulants (DOACs) are also available. 

Thromboprophylaxis is highly effective, safe, and cost-effective. However, data from international studies has shown that many at-risk hospitalised patients do not receive appropriate prophylaxis, leaving them at risk of VTE and its consequences. A significant number of at-risk patients, who subsequently developed VTE after discharge from hospital, had not received appropriate thromboprophylaxis during their hospital admission. 

Case study

Alison Johnson, partner in the clinical negligence team at Penningtons Manches Cooper, has settled a claim for a woman tragically widowed young. Her late husband had a medical history of a DVT following a long-haul flight. He was then anticoagulated with warfarin and, for a time, had to use crutches to mobilise. At around the same time (possibly through having to use crutches) he developed a problem with his right Achilles tendon, for which he had an orthopaedic referral, and was advised to undergo surgery in the form of a bilateral gastrocnemius release, which went ahead. The defendant NHS trust (according to its own serious incident report) concluded that the deceased’s ‘high risk of VTE (venous thromboembolism)’ was not recognised on several occasions, both before and during his day surgery.

One week following surgery, the deceased collapsed at home and died. He had suffered a cardiac arrest caused by a pulmonary embolism. The deceased was aged only 54 when he died.

We brought a claim and secured an admission of liability that the NHS trust had failed to recognise that the deceased ‘was at a high risk of VTE’. On causation, we outlined our client’s case that ‘on the balance of probabilities adequate VTE prophylaxis would have prevented the further DVT the deceased suffered, and he would have avoided the fatal pulmonary embolism’. Ultimately, this led to a full admission of breach of duty and causation and the claim was settled for a significant six figure sum in damages.

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