The death of Lady Joan Branson, wife of billionaire entrepreneur Sir Richard Branson, has highlighted the risk of a blood clot after fractures that travels to the lungs.Lady Branson, 80, died at Lister Hospital in London in November 2025 after being admitted following a fall at her home on Necker Island. An inquest heard that she had developed a deep vein thrombosis (DVT) and subsequently suffered a massive pulmonary embolism (PE).The coroner, Professor Fiona Wilcox, concluded that her death could probably have been prevented if anti-clotting treatment had been given earlier. She said: “If this lady had been given [anti-clotting medication] early on ... her death, on the balance of probability, would have been prevented.” What exactly happens after a fracture that can make a blood clot so dangerous?Fracture Increases The Risk Of Blood ClotsA fracture can trigger several conditions that encourage the development of venous thromboembolism (VTE), the collective term for DVT and PE.First, injury itself activates the body's clotting system. The body naturally increases clot formation after tissue damage to prevent bleeding.Second, a person with a fracture may become significantly less mobile. When the leg muscles are not moving normally, the muscle pump that helps push blood through the veins becomes less effective. Blood can therefore pool in the deep veins, particularly in the legs. Hospitalisation, surgery, older age, previous blood clots and certain medical conditions can add further risk.A clot that remains in a leg vein can cause swelling and pain. But when part of it breaks and gets away, it can travel through the bloodstream to the lungs, leading to a pulmonary embolism.Also read: 9/11 Toxic Air Exposed Thousands: What New Records Reveal 25 Years LaterHow Does A DVT Become A Pulmonary Embolism?A clot forming in a deep vein, usually in the leg, can detach and travel through the veins into the right side of the heart. From there, it can enter the pulmonary arteries, which carry blood to the lungs.If the clot is large enough, it can obstruct blood flow through the lungs and suddenly increase pressure on the right side of the heart.A large or massive PE can therefore cause severe breathlessness, low blood pressure, cardiac arrest and sudden death.This is why PE can sometimes appear dramatically, even when the original DVT produced few obvious symptoms.Also read: Small-Cell Lung Cancer Is One Of The Hardest Cancers To Treat: What This New Drug Combination Could ChangeCould Blood-Thinning Medication Have Prevented Lady Branson’s Death?According to the inquest, Lady Branson had a history of blood clots dating back to 2010, and doctors heard evidence that she had previously used anti-clotting injections.However, she was not given enoxaparin, a low-molecular-weight heparin commonly used to prevent or treat harmful blood clots, during her hospital stay.One doctor, Dr Inaki Bovill, told the inquest that a venous thromboembolism risk assessment should have been carried out and that the medication should have been prescribed. He said: “It is to my great regret that I did not.” Another doctor, Dr George Adams, a consultant haematologist at Imperial College London, told the inquest that earlier anticoagulation would have made cardiac arrest less likely in her particular case. Lady Branson's daughter, Dr Holly Branson, disputed the suggestion that her mother had refused the injections because of previous pain or bruising. She told the inquest that this was “not consistent with my knowledge of her usual practice or attitude.” What Are The Warning Signs Of A Blood Clot?A DVT can cause:Swelling, usually in one legPain or tenderness in the calf or thighWarmth or redness over the affected areaA PE may cause:Sudden unexplained breathlessnessChest pain, particularly pain that worsens when breathingRapid heartbeat or breathingCoughing up bloodDizziness, fainting or collapse