This study aims to determine the use of diagnostic imaging in emergency department (ED) observation units, particularly relative to inpatients admitted from the ED.

Retrospective, descriptive analysis.

Our database of ED patients was retrospectively reviewed to identify patients managed in the observation unit or admitted to inpatient services. In February 2014, we randomly selected 105 ED observation patients and 108 patients admitted to inpatient services from the ED. Electronic medical records were reviewed to assess diagnosis as well as type and quantity of imaging tests obtained.

Eighty (76%) ED observation patients underwent imaging tests (radiographs, 39%; computed tomography, 25%; magnetic resonance imaging (MRI), 24%; ultrasound, 8%; other, 4%); 85 inpatients (79%) underwent imaging tests while in the ED (radiographs, 52%; computed tomography, 30%; MRI, 8%; ultrasound, 9%; other, 1%). There was no significant difference in overall imaging use between ED observation patients and inpatients, but ED observation patients were more likely to undergo MRI (P=.0243). The most common presenting diagnoses to the ED observation unit were neurologic complaints (25%), abdominal pain (17%), and cardiac symptoms (16%).

There is no difference in the overall use of imaging in patients transferred to the ED observation unit vs those directly admitted from the ED. However, because ED observation unit patients tend to be accountable for a higher proportion of their health care bill, the impact of imaging in these patients is likely substantive.