Cost Comparison of Ultrasound Versus MRI to Diagnose Adolescent Female Patients Presenting with Acute Abdominal/Pelvic Pain Using Time-Driven Activity-Based Costing.

RATIONALE AND OBJECTIVES: To compare the cost of ultrasound (US) versus magnetic resonance imaging (MRI) using time-driven activity-based costing in adolescent female patients with suspected appendicitis.

MATERIALS AND METHODS: Process maps were created using data from electronic medical record review and patient shadowing for adolescent female patients undergoing US or noncontrast MRI exams of the abdomen and pelvis for suspected appendicitis. Capacity cost rates for all personnel, equipment, facilities, and supplies in each exam pathway were established from institutional accounting data. The cost of each process step was determined by multiplying step-specific capacity cost rates by the mean time required to complete the step. Total pathway costs for US and MRI were computed by summing the costs of all steps through each pathway, and a direct cost comparison was made between the two modalities.

RESULTS: Process maps for US and MRI pathways were generated from 231 and 52 patient encounters, respectively. Patients undergoing US exams followed one of six pathways depending on exam order (abdomen versus pelvis performed first) and whether additional time was needed for bladder filling. Mean total US pathway time was 91 minutes longer than for MRI (US = 166 minutes; MRI = 75 minutes). Total MRI pathway cost was $209.97 compared to a mean US cost of $258.33 (range = $163.21-$293.24).

CONCLUSION: MRI can be a faster and less costly alternative to US for evaluating suspected appendicitis in adolescent female patients. While precise costs will vary by institution, MRI may be a viable and at times preferable alternative to US in this patient population.