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Objective:
The COVID-19 global pandemic has resulted in significant morbidity and mortality worldwide. A well-recognized sequela of infection is the induction of a severe pro-inflammatory state within its host [1], creating a hypercoagulable state and increases the frequency of developing venous thromboembolism (VTE), which includes both deep venous thrombosis (DVT) and pulmonary embolism (PE) [2]. Imaging plays a crucial role in the diagnosis and work-up of COVID-19. Direct contact with an infected patient is required during ultrasound scanning, increasing the risk of contracting the illness and the likelihood of perpetuating the prevalence of disease in the population. This led to modifications in various imaging protocols in COVID-19 (+) patients to reduce technologists' exposure time. The purpose of this study was to examine the benefits of implementing an abbreviated venous duplex US protocol for the detection of DVT in COVID-19 (+) patients. Our hypothesis is that this would result in less exposure time for the technologist, thereby lowering the risk of transmission of the infection, without significantly changing the VTE detection rate.

Materials and Methods:
A single-center retrospective study was performed at a single large tertiary care hospital from October 2019 through December 2021. From October 2019 through December 2020, all hospitalized COVID (+) patients who received a bilateral lower extremity (BLE) venous duplex ultrasound for DVT detection utilized our conventional protocol. This included scanning the femoral, popliteal, tibioperoneal trunk, and peroneal veins. From January 2021 through December 2021, all COVID (+) patients who received a BLE venous duplex ultrasound for the detection of DVT utilized our abbreviated protocol. This included scanning all of the aforementioned veins, with the exception of the peroneal/calf veins. Exam duration and presence/location of venous thrombosis were documented.

Results:
320 patients underwent 337 BLE DVT exams, including 17 patients with two exams. 214 and 106 patients were imaged using conventional and abbreviated protocols, respectively. In the conventional cohort, 33 DVTs were detected and 7 of these patients went on to develop PE. Of the 181 patients who were negative for DVT, 18 developed PE. In the abbreviated cohort, 8 DVTs were detected and 3 of these patients developed PE. Of the 98 patients who were negative for DVT, 12 developed PE.

Conclusion:
Prevalence of PE in the conventional protocol and abbreviated protocol cohorts were 11.7% and 14.2%, respectively, and not significantly different (P=0.591, 2-sided Fisher’s exact test). A marginally higher rate of DVT was observed in the conventional cohort (15.4% vs. 7.5%, P=0.052, 2-sided Fisher’s exact test). Sensitivity for detecting PE was low for both protocols (28% vs. 20%) and was not different (P=0.715, 2-sided Fisher’s exact test). Significantly shorter exam duration was observed in the abbreviated cohort (median: 15.7 vs. 23.2 min, P<0.001, Kruskal-Wallis test). The abbreviated protocol led to a shorter exam duration without changing the detection rate for VTE.