Decreasing Duplicative Imaging: Clinical Decision Support Intervention to Reduce Unnecessary Abdominal Ultrasound Following Abdominal CT

From the 2019 HVPAA National Conference

Dr. Neb Adenaw (Johns Hopkins Department of Radiology), Dr. Jessica Wen (Johns Hopkins Department of Radiology), Dr. Pamela Johnson (Johns Hopkins Department of Radiology)


Duplicative imaging contributes to unnecessary health care expenditure. This initiative was designed to reduce inpatient and emergency department (ED) abdominal ultrasound exams in patients who had undergone abdominal CT within 72 hours prior to the US order being placed. The diagnostic information in question is often already available on the abdominal CT scan. The most common scenario for this is inpatient acute kidney injury (AKI), which is usually due to causes other than renal obstruction, but renal ultrasound is reflexively ordered by house staff and faculty.


Baseline review of reports on 100 inpatients in 2015-2016 imaged for AKI with renal ultrasound (US) revealed absence of hydronephrosis in 89% (89/100). Additional imaging utilization review over a 2 month period in 2017 identified 50 patients imaged with renal US within 10 days after abdominal CT, with a mean time interval of 2.4 days between the US and CT. A best practice advisory (BPA) was created in the electronic medical record (EMR) to advise against routine use of abdominal ultrasound in adult inpatients and ED patients who had undergone an abdominal CT within the preceding 72 hours. Using Diagnosis Group Identifiers, patients with transplants and oncology patients were excluded; many of these patients are unable to receive intravenous contrast enhanced CT and noncontrast CT provides limited information.

Two separate BPAs were designed, depending whether the CT result was pending or finalized. Acceptable acknowledgement reasons to proceed with the order were made available with the BPA:

  • Radiologist recommended ultrasound
  • Transplant patient
  • Evaluate gallbladder
  • Evaluate vasculature because CT was noncontrast
  • Paracentesis mark
  • Relevant intervention in the interval (e.g. nephrostomy tube)
  • Discussed with radiologist
  • Other

The frequency of BPA firing and subsequent ordering were evaluated after launching the BPA in the EMR in December 2017. For all patients whose ultrasounds were canceled, chart review was conducted to confirm that patient care quality and safety were not compromised.


In the 1st 6 months of 2018, a total of 614 inpatient and ED abdominal US orders were placed in patients with a preceding abdominal CT. Following the BPA, only 16% (96/614) of the US orders were canceled.  Using an average charge of $457 for abdominal US, the projected annual charge reduction is $85,000 for this intervention.

Review of free text comments revealed 42 US exams for AKI or stones that could have potentially been avoided, reflecting a need for better education and prompting modification of the BPA to emphasize that AKI was a primary area of overuse. Chart review of 100 patients who received US following CT demonstrated a paucity of contributory findings in evaluation of the kidneys, liver and biliary tree. Of note, gallbladder evaluation with US often revealed or clarified clinically significant findings not definitely identified on CT.Additional chart review of the 96 patients whose ultrasound exams were canceled confirmed that the ultrasound would not have contributed value to patients’ care.


Outside of gallbladder imaging, abdominal CT usually provides more diagnostic information than abdominal ultrasound. Inpatient abdominal ultrasound may be obviated by a recently performed abdominal CT scan, particularly renal ultrasound in the setting of hospital acquired AKI. Implementing a smart BPA can safely reduce wasteful practice and decrease patients’ total cost of care, but low rate of canceled orders underscores need for more education and feedback reports.


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