In venous thromboembolism, a blood clot usually forms in the deep veins of the legs or pelvis. This is known as deep vein thrombosis, and the blood clot can dislodge from these sites, resulting in pulmonary embolism.
In 2020, the National Institute for Health and Care Excellence (NICE) first published guidance on the diagnosis and management of venous thromboembolic disease.1 Since then, new evidence has emerged which indicates that people with covid-19 have a higher risk of developing venous thromboembolism and elevated D-dimer levels, and that this risk increased with severity of covid-19 infection. In the 2021 British Thoracic Society guidelines on venous thromboembolism in patients with covid-19, one meta-analysis of 49 studies reported an incidence of venous thromboembolism of 17% in people with covid-19, and that the incidence was higher in patients in intensive care (28%) compared with those on a medical ward (7%).2 D-dimer, a protein fragment that can represent a by-product of blood clotting, is often elevated in severe covid-19 as a result of severe lung inflammation.2 This can challenge the usefulness of D-dimer testing for predicting the presence of venous thromboembolism.
In addition, the 2020 guidelines recommend using the pulmonary embolism rule-out criteria (PERC) to rule out pulmonary embolism. However, a Healthcare Safety Investigation Branch report identified that some clinicians were reporting difficulty in quantifying risk of pulmonary embolism as a …