The incidence of acute lower limb thrombosis, in symptomatic patients detected with ultrasound, with consideration of recent COVID‐19 vaccination or infection

Abstract

AbstractIntroductionAfter the COVID‐19 vaccination roll out began in March 2021 patients began presenting to a Victorian Emergency Department with lower limb pain following their vaccination. As a result, radiology requests for ultrasound examinations, to exclude post vaccination deep vein thrombosis (DVT) began appearing.MethodA retrospective search of lower limb venous ultrasound examinations was undertaken for a 1‐year period from March 2021 to February 2022. Patients were included in the study if they had a clinical indication of having been referred following COVID‐19 vaccination. Bivariate analysis was conducted, using logistic regression, to determine the strength of association between independent variables (i.e., age, gender, vaccination status, and COVID‐19 diagnosis) and dependent variables (i.e., a diagnosis of DVT and superficial vein thrombosis [SVT]).ResultsThe study found 1627 examinations had a lower limb venous ultrasound examination over the study period. Ultrasound was positive for acute DVT in 218/1627 examinations (13.4%). 104/1627 (6.4%) presented for ultrasound following COVID‐19 vaccination. Six of these were found to have acute lower limb DVT detected. The association between post vaccination and DVT was an odds ratio (OR) of 0.379 (95% CI 0.164–0.874, p = .023). All examinations that were diagnosed with acute thrombus had recently received AstraZeneca (AZ) (Vaxzevria, ChAdOx1‐S/nCoV‐19) vaccine. Four examinations were diagnosed with superficial vein thrombosis (SVT) post recent COVID‐19 vaccination. One patient was diagnosed with Vaccine Induced Thrombosis with Thrombocytopenia after their first dose of AZ.ConclusionThis study found 6/1627 (0.37%) lower limb venous ultrasound examinations, over a 1‐year period, were positive for acute DVT after COVID‐19 vaccination. The results showed post vaccination examinations were less likely to be diagnosed with a DVT than the population referred who had not had recent vaccination.