Prevention and Treatment of Venous Thromboembolism Key Clinical Questions
09. What is the diagnostic algorithm for pulmonary embolism (PE) in the setting of COVID?
a. HOMERuN institutions
11/21 institutions (52%) gave some guidance on the diagnostic algorithm for PE, although there was variability in these recommendations and the exact steps in evaluation were often largely left up to clinician judgment. Some recommendations included using Wells score for risk assessment, baseline DVT ultrasound as well as repeat ultrasound for changes in clinical status, point of care TTE and venous doppler for patients with elevated D-dimer or clinical signs/symptoms, and obtaining PE protocol CTA for patients with clinical features of PE. Overall, most protocols essentially recommended following the usual algorithm for non –COVID-19 patients, albeit with comments that clinicians should consider having a lower threshold to consider this diagnosis in COVID-19 patients given their increased risk of VTE.
b. What is Known
A number of cohort studies have been published showing that there appears to be an increased incidence of VTE in COVID-19 patients, even in patients receiving prophylactic anticoagulation.
c. What is Not Known
The exact risk of VTE varies between studies, and to date these studies are small and of variable quality. Even with a known increased risk of VTE, it is not clear at this time how this should affect the diagnostic algorithm for VTE in COVID-19 patients or than to say that clinicians should have increased suspicion for VTE in COVID-19 patients. There has also been some discussion of microvascular pulmonary thrombosis in COVID-19 which might warrant anticoagulation but would not result in an evident PE on CT scanning, so it is not known if this should impact which diagnostic test is ordered or how tests are interpreted.