391 Routine Hatobiliary Iminodiacetic Acid Scan of All Suspected Cases of Acute Cholecystitis

Abstract

Cholecystitis is the second-most common surgical admission from emergency departments and represents a large health burden. Different imaging modalities are utilized to evaluate this disease while hepatobiliary iminodiacetic acid (HIDA) scans are reported to be more sensitive and specific for acute cholecystitis because it is a functional evaluation of the gallbladder and can demonstrate cystic duct obstruction. Most emergency departments obtain a HIDA scan when the clinical diagnosis is equivalent. At our center, the primary general surgery group requires routine HIDA scans on all suspected cases of acute cholecystitis before deciding operative management. The purpose of this study was to perform a retrospective review of all HIDA scans performed in 2018 among emergency department cases of suspected cholecystitis. The specific aim was to evaluate the agreement between ultrasound (US) and HIDA scan findings and their association with operative decision-making. Secondary objectives were to evaluate discrepancies, insurance status, age, sex, ED length-of-stay, operative outcomes, and costs. HIDA scans were identified from our imaging record system from January 1, 2018 to December 31, 2018. An abnormal US (US+) was defined as the presence of gallstones plus either of the following: gallbladder wall thickening, pericholecystic fluid, sonographic Murphy’s, or common bile duct dilatation. An abnormal HIDA (HIDA+) scan was defined as cystic duct obstruction and/or failure to visualize the gallbladder. Qualitative reviews of specific cases were summarized. STATA (College Station, TX) was used for statistical analysis. N = 550 patients who received both HIDA scan and gallbladder US. There were 348 cases of US+ and 234 cases of HIDA+. There was a 59.3% agreement between US and HIDA findings. n = 169 of US+ and HIDA- and n = 55 of US- and HIDA+. Pairwise correlation 0.236 (p<0.001). There was a net decrease in operative care of 114 cases by adding HIDA. 550 HIDA scans have an estimated aggregate charge of $773,300 whereas 114 fewer laparoscopic cholecystectomies would have an aggregate savings of $2,101,932. This is the largest single-center study of comparison between HIDA and US in emergency department patients. The use of HIDA scans suggested 49% of patients with US+ findings may not require urgent surgery whereas 27% of patients with non-diagnostic US demonstrated the need for surgical intervention. The routine use of HIDA scans may have a significant impact on costs and reimbursements for this common etiology. The clinical suspicion is the main driver of resource utilization and routine HIDA scans increase immediate costs, ED length-of-stay, and can result in a net decrease of costs for urgent operative care.