World Thrombosis Day 2022: Circulating knowledge to keep the world flowing

Did you know that 1 in 4 people worldwide die of conditions related to thrombosis? [1]. October 13th marks World Thrombosis Day, a campaign designed to spread information and raise awareness of the sometimes overlooked condition of thrombosis. Running since 2014, the event comprises thousands of educational events across the globe to signpost thrombosis as an urgent and mounting health problem.


What is thrombosis and why should we be more aware?

Thrombosis occurs when a clot develops inappropriately inside a blood vessel such as a vein or artery. Although blood clotting at site of injury is a normal function of blood, thrombosis is a condition of concern – clots occurring in a blood vessel can grow to form a blockage known as a thrombus [2].

Once formed, a thrombus can restrict blood flow, and present further danger by breaking free – allowing its passage into an organ. In the circulatory system, this is called an embolism. Thrombosis can be life-threatening, frequently manifesting as cardiac arrest, thromboembolic stroke, and venous thromboembolism (VTE).

VTE is of particular concern, and occurs when blood clots form in the deep veins of the leg, known as deep vein thrombosis (DVT). From there, clots may travel to the lungs, where they can lodge and cause a pulmonary embolism (PE), to devastating effect [3]. Approximately 1 in 10 people with a DVT if left untreated will develop PE [1].
Front and center of World Thrombosis Day’s message however, is that while thrombosis, and especially VTE, presents a great danger to global health, many of the contributing risk factors can be avoided with lifestyle changes and evidence-based prevention strategies.

As VTE is the number one cause of preventable deaths in hospital [1], a key step towards reducing the burden of thrombosis on global health, is to identify “at-risk” individuals.


Who is most at risk from VTE?

To identify whether a patient is 'at-risk', clinicians routinely conduct a VTE risk assessment in the form of a questionnaire to determine the patient's age, medical history, medications and contributing lifestyle factors. The data can then be used to categorize individuals as having a high, moderate or low risk of developing thrombosis or PE.

The most prominent risk factors for developing VTE are set out below [4]:


Attributable risksConditions and treatmentsFamily and lifestyle
  • Hospitalization for illness or surgery
  • Major surgery, particularly of pelvis, abdomen, hip or knee
  • Severe trauma, e.g. car accident
  • Injury to a vein, e.g. caused by broken bone or severe muscle injury
  • Hip or knee replacement surgery
  • Cancer and cancer treatments
  • Contraception containing oestrogenm e.g. the pill, patch or ring
  • Pregnancy, including the six weeks after birth
  • Hormone therapy (HRT) containing oestrogen
  • A family history of blood clots 
  • Obesity
  • Long-term bed rest
  • Long periods of inactivity, e.g. sitting for a long time, especially with legs crossed


The likelihood of VTE increases dramatically with age, with under 40s having an incidence rate of approximately 1 in 10,000, whereas at >80 years the incidence rate is 1 in 100 [5]. However, the highest risk factor for developing VTE is long hospital stays, with 55-60% of all VTE cases occurring during or after hospitalization [1].


How can DVT or PE be diagnosed and treated?

If a patient is deemed to be at high-risk, there are a number of tests that can be administered to see if a blood clot is present [6]:

  • D-Dimer blood test for clots
  • Ultrasounds of limbs for DVT
  • CAT scan of the chest for PE


As well as testing for thrombosis, various preventative treatments can be prescribed:

  • Anticoagulant medications
  • Mechanical devices (e.g. compression stockings)


If diagnosed, DVT and PE require immediate medical attention. Treatment includes the prompt administration of anticoagulant medication to destroy clots and prevent further clotting. Furthermore, mechanical devices and thrombolytic therapy may be utilised. Diagnosing and treating DVT and PE as early as possible gives patients the greatest chance of recovery [4].


Diagnostic details

As discussed, prompt diagnosis is critical in ensuring relevant and timely treatment. Prior to any testing, a pre-test probability assessment is performed (Wells score) as it could be that there is sufficient clinical evidence to suggest the strong likelihood of a DVT and venous ultrasound can be performed and treatment started immediately.

If a DVT/PE is unlikely based on the pre-test probability assessment, then a simple D-dimer blood test is undertaken to fully exclude DVT/PE. D-dimer is produced when cross-linked Fibrin is broken down during the fibrinolytic process. D-dimer is normally undetectable or at a very low level in the body unless clots have been formed.

The D-dimer result is used as a negative predictor for DVT/PE, with values below the cut-off excluding the possibility of a thrombotic event. Patients with raised levels above the normal range cut-off value are then assessed with venous ultrasound and treated accordingly.

HORIBA Medical has produced a D-dimer reagent for use on its Yumizen G series of hemostasis analyzers which requires no reconstitution and provides accurate results, even at high levels of hemolysis.


Helping to monitor recovery

For individuals prescribed anticoagulant medication as a prophylactic or treatment for thrombosis, HORIBA Medical offers a range of hemostasis reagents and analyzers to help clinicians to both diagnose and then track their patients’ progress. Find our hemostasis guide here.

For more information on the event, and to find out how you can get involved, please visit the World Thrombosis Day home page at:



1. Thrombosis UK. Thrombosis statistics. Available from: 
2. World Thrombosis Day. Understanding Thrombosis. Available from: 
3. National Heart, Blood and Lung Institute. What Is Venous Thromboembolism? Available from: 
4. NHS. Deep vein thrombosis. Available from: 
5. Heit, J. Epidemiology of venous thromboembolism. Nat Rev Cardiol. 2015 Aug; 12(8): 464–474. Available from: 
6. NICE Guidelines. Venous thromboembolism: diagnosis and anticoagulation treatment. Available from: