MP08-02 PATTERNS OF CT AND US UTILIZATION FOR NEPHROLITHIASIS IN THE EMERGENCY DEPARTMENT

INTRODUCTION AND OBJECTIVES:A previous randomized trial found that obtaining ultrasound (US) as the first diagnostic imaging study for adults with suspected ureteral stones reduces radiation without increasing return ED visits or missed diagnoses. These results are consistent with EAU guidelines that US should be the first imaging modality for nephrolithiasis. We sought to determine the potential reduction in radiation exposure for an US-first approach using population-based diagnostic imaging patterns in the ED.METHODS:We performed a cross-sectional study of adults who presented to 70 emergency departments in South Carolina between 1996 and 2017 using all payer hospital claims data. All ED encounters within a 6 month “episode” following the initial ED visit were identified, along with ultrasound and CT ordered at the visits. Patterns of US and CT during the first two consecutive ER visits were determined at the patient- and hospital-level. Imaging patterns in which only a CT was performed were classified...