October 2021: World Thrombosis Day - Eyes Open To Thrombosis

by Donna Castellone, MS, MT (ASCP) SH • October 07, 2021

The interpretations below are provided by Donna Castellone, MS, MT (ASCP) SH for Aniara Diagnostica.

After spending 19 months behind a mask for most of the day, a most relevant title for World Thrombosis Day is Eyes Open to Thrombosis. WTD occurs on October 13th the birthday of Rudolf Virchow. This German physician developed the concept of thrombosis and was a pioneer in the pathophysiology of thrombosis. The purpose of this day is to highlight the burden of this disease and the consequences related to venous thromboembolism (VTE) and atrial fibrillation (AF). This day is to increase public awareness of the symptoms of thrombosis as well as the causes and to encourage people to discuss possible risk factor with their healthcare providers.1 Several topics this year are the focus of WTD.


Hospital Associated VTE:

There are several reasons that people in the hospital are at an increased risk of venous thromboembolism which include decreased mobility or blood vessel trauma due to surgery or injury. These situations contribute to the formation of blood clots. Up to 60% of VTE occur within 90 days of hospitalization, which is preventable.2 In the US more than 540,000 hospitalized patients develop VTE.3 Certain surgeries are considered a higher risk for VTE such as orthopedic, general surgery of abdomen, pelvis, hips, gynecological surgery, cardiac, vascular surgery and chemotherapy. Patients should be evaluated for VTE risk prior to these surgeries.

Studies have showed that acquired VTE prevalence rates for VTE are between 0.8-11%.4 There are several risk assessments that can be utilized including the Caprini risk assessment for surgical patients and the modified Padua risk assessment for medical patients. The major outcomes of these assessment is to prevent VTE with therapy based on the individuals bleeding and VTE risk. Therapy can include either mechanical or pharmacologic options.

Recommendations for the prevention of VTE in hospitalized patients include evaluating their risk within 24 hours of admission or transferring the level of care as well as periodically during the hospital stay. There is no universally validated model to assess bleeding risk but it does have an association with bleeding 3 months prior to admission, active bleeding, a platelet count of less than 50 x 109, as well a those with renal or hepatic failure.5


Padua prediction score4

Padua prediction score


The distribution of the individual risk factors for venous thromboembolism (VTE) according to the Caprini score6

Risk Factors



Covid patients present with elevated biomarkers that are commonly seen in patients with high levels of inflammation and clotting. It is referred to as "thrombo-inflammation". These patients present with the highest risk of death from COVID-19. These patients with high levels of thrombo-inflammation appear to have tiny clots that form in the inflamed lungs and may contribute to respiratory failure. Survival rates were improved with the use of anticoagulants.7

The hemostatic changes seen in COVID-19 patients include very high levels of acute phase reactants, high levels of D-dimer with high rates of VTE and a high rate of pulmonay immuno-thrombosis. There is a significant cross-link between coagulation and inflammation. Severe COVID-19 infection generates an increase in proinflammatory cytokines and activates endothelial cells, neutrophils, mono nuclear cells and platelets leading to tissue factor activated coagulation. Coagulation proteases bind specific receptors that mediate further pro-inflammatory responses resulting in the activation of coagulation that may further modulate inflammatory responses.8

Coagulation laboratory characteristics of COVID-19 infection


World Thrombosis Day Supports World Patient Safety Day:

In 2019 the WHO established World Patient Safety Day to enhance global understanding of patient safety, increase public engagement in the safety of health care and promote global actions to enhance patient safety and reduce patient harm. This year the calling is for safe maternal and newborn care in particular during childbirth. The slogan is "Act now for safe and respectable childbirth". One in four deaths is a result of thrombosis related conditions and women have increased risk for VTE due to pregnancy and in the six weeks after childbirth. It is important for both patients and clinicians to be aware about their risk for developing a blood clot.1



Having your eyes open for yourself and family and patients is an important step in minimizing the risk of VTE. Understanding the importance of the evaluation of a patients' risk and the benefit understanding the risk is an important objective of World Thrombosis Day. The ultimate goal is to prevent VTE by increasing awareness.



  1. https://www.worldthrombosisday.org/
  2. Jha AK, Larizgoitia I, Audera-Lopez C, Prasopa-Plaisier N, Waters H, Bates DW. The global burden of unsafe medical care: analytic modeling of observational studies. BMJ Qual Saf 2013; 22;809-15.
  3. Yusuf H, Tsai J, Atrash H, Boulet S, Grosse S. Venous thromboembolism in adult hospitalizations–United States – 2007-2009. MMWR 2012;61:no. 22:401-404
  4. Barbar S, Noventa F, Rossetto V, et al. A risk assessment model for the identification of hospitalized medical patients at risk for venous thromboembolism: the Padua Prediction Score. J Thromb Haemost. 2010; 8(11):2450-2457.
  5. Decousus H, Tupson VF, Bergman JF, et al. IMPROVE Investigators. Factors at admission associated with bleeding risk in medical patients: findings from the IMPROVE investigators. Chest. 2011;139(1):69-79.
  6. Tsaplin S, Schastlivtsev I, Zhuravlev S, Barinov V, Lobastov K, Caprini JA. The original and modified Caprini score equally predicts venous thromboembolism in COVID-19 patients. J Vasc Surg Venous Lymphat Disord. 2021 Mar 17.
  7. Masten, A., Isth Experts Explain New Blood Clotting Phenomenon In Hospitalized Covid-19 Patients, Sunday, July 12, 2020 https://www.isth.org/news/516793/ISTH-Experts-Explain-New-Blood-Clotting-Phenomenon-in-Hospitalized-COVID-19-Patients-.htm
  8. Levi, M., Hunt, BJ., Thrombosis and coagulopathy in COVID-19: An illustrated review Research and practice in Thrombosis and Haemostasis, 11 July 2020