Factors associated with positive thrombus findings at ultrasonography in COVID-19 ward patients who underwent imaging for suspected deep vein thrombosis under prophylactic anticoagulation

OBJECTIVE: The incidence of deep vein thrombosis (DVT) is increased in patients with coronavirus disease 2019 (COVID-19) and its presence is associated with worse outcomes. Ultrasound examination of patients with COVID-19 with a suspected DVT is challenging owing to concerns with disease transmission; the timely initiation of therapeutic anticoagulation is essential. This study aimed to identify patient factors associated with positive thrombus findings at ultrasound examination in patients with COVID-19 who underwent imaging for suspected DVT. METHODS: Patients who did not require intensive care unit treatment and who underwent ultrasound imaging for suspected DVT between March and December 2020 were included retrospectively. Patient demographics, comorbidities, modified Well’s score, and d-dimer results on the day of ultrasound examination were recorded. Parameters for a higher likelihood of a positive DVT result were determined by comparing patients with confirmed DVT on ultrasound examination and patients with negative ultrasound findings. To determine a cut-off for d-dimer levels, a receiver operating characteristic curve was constructed. The sensitivity and specificity of the determined high-risk factors in the prediction of positive ultrasound results were calculated. RESULTS: A positive history for DVT (25% vs 4%; P < .001), thrombophilia (9% vs 2%; P = .048), immobilization (53% vs 23%; P = .001), and a Well’s score ≥ 2 (50% vs 21%; P = .001) were more frequent in patients with DVT. The mean d-dimer levels were higher in patients with DVT (3871 ± 1805 vs 2075 ± 1543; P < .001). The presence of either thrombophilia or a d-dimer level of >2020 had a sensitivity of 93% and a specificity of 64%. The presence of either thrombophilia, a d-dimer level of >2020, or a Well’s score of ≥2 had a sensitivity of 100% and a specificity of 51%. CONCLUSIONS: Patients with COVID-19 with a d-dimer of >2020, a positive history for thrombophilia, and a Well’s score of ≥2 should undergo a timely ultrasound examination. The high risk of DVT should be remembered for all hospitalized patients with COVID-19.