E1504. Association of Extremity Venous Doppler Ultrasound DVT Results Between Initial and Subsequent Exams
  1. Travis Browning; UT Southwestern Medical Center
  2. Ali Tejani; UT Southwestern Medical Center
  3. Yin Xi; UT Southwestern Medical Center
  4. David Fetzer; UT Southwestern Medical Center
  5. Julia Fielding; UT Southwestern Medical Center
This study assesses the association of the initial result of Venous Doppler ultrasound (VDU) of the extremity with the subsequent result for patients undergoing repeat examination of the same limb for deep venous thrombosis (DVT).

Materials and Methods:
Structured reports for VDU reports (1/20/2016 to 7/20/2019) were analyzed for DVT outcomes. Structured reports have a fixed picklist impression: acute, calf only, or known DVT, chronic post-thrombotic change, and superficial vein thrombus. Multivariable logistic regression was used to estimate the effect of the result of previous DVT of the same extremity while adjusted for priority, class and upper vs lower extremities identified by our previous study as significant effects. All analyses were done in SAS 9.4.

Of the 54181 VDU reports from 01/20/2016 to 07/20/2019, 52884 (97.6%) utilized the structured reporting system and 7254 (13.72%) reported any DVT with a rate of 10.0% and 23.4% for lower and upper extremities, respectively. After accounting for bilateral exams, 77282 total individual limb exams were performed with 7562 patients undergoing repeat limb evaluation for a total of 42037 (54.4%) initial and repeat exams. Adjusted by logistic regression model, positive (+) DVT rate following a negative (-) result exam on the same limb was 4.1% (95% CI (3.6%, 4.6%)) for legs and 15.0% (95%CI (12.2%, 18.5%)) for arms. (+) DVT rate following a (+) result exam was 66.3% (95% CI (63.4%, 69.0%)) for legs and 52.4% (95%CI (46.1%, 58.6%)) for arms.

Structured reporting can help monitor imaging interpretation outcomes at an enterprise level. In our system, repeat limb evaluation accounts for a high percent of VDU exams. For patients with repeat exams of the same extremity, an initial negative VDU for DVT correlates with a higher rate of negative result on subsequent US compared to the population rate. Initial positive exams correlate with higher rates of positive results on repeat imaging. This suggests that an initial negative test result might impact the pretest probability of repeat imaging in some situations.