Incidence of Non-thrombotic Diagnoses Following Venous Duplex Ultrasound at a Community Emergency Department

Background: When used as a diagnostic aid for diagnosing deep vein thrombosis (DVT), venous duplex ultrasound (US) may reveal non-thrombotic findings in those with acute extremity pain. The objective of this study was to determine the prevalence and predictors of non-thrombotic findings on venous duplex US at a community emergency department. Methods: A retrospective chart review of all adult patients who presented to a community emergency department who underwent either an upper or lower extremity venous duplex US for the evaluation of DVT from June 1, 2019, to September 15, 2020. All US studies were completed by certified sonographers and interpreted by board-certified radiologists. Two trained research assistants manually abstracted patient demographics and US findings. Data were analyzed using the chi-square statistic for categorical variables and the student's independent t-test for continuous variables. Multivariate binomial regression was used to identify independent predictors of non-thrombotic results on venous duplex US. Results: A total of 1,448 venous duplex US were obtained during the study period with 126 DVTs being diagnosed. A total of 1071 US had no acute abnormality and 252 had non-thrombotic findings. All non-thrombotic findings were found in the lower extremity. Of those with non-thrombotic findings, the most common diagnoses included edema (34.9%, 88/252), Baker’s cyst (22.6%, 57/252), and an unspecified fluid collection (16.3%, 41/252). Patients with non-thrombotic findings were more likely to have a history of atrial fibrillation (p=0.001) or hypertension (p=0.001), be older than the age of 70 (p=0.042), or have a history of using illicit drugs (p=0.003). Females were less likely to have non-thrombotic findings. Conclusion: In this single-site study, non-thrombotic findings were present in 23.5% of all venous duplex US completed at a community emergency department. These findings are more common in the elderly, those with cardiovascular disorders, and those who have used illicit drugs.