PURPOSE: To examine temporal trends and outcomes of outpatient adrenalectomy in a population-based sample. METHODS: We performed a retrospective cohort study using the Healthcare Cost and Utilization Project's State Inpatient and State Ambulatory Surgery Databases, 2016-2020. Patients undergoing minimally invasive adrenalectomy were identified using billing codes. The primary exposure was admission status defined by length of stay. Outcomes included temporal trend in admission type, readmission rates and costs. RESULTS: Among 4431 adrenalectomies, 51.3 % were performed in the outpatient setting. The majority were observed overnight with only 100 patients (2.3 %) discharged same-day. Outpatient adrenalectomy increased annually from 44.1 % in 2016 to 59.2 % in 2020 (p <
0.01). Median costs were similar with a risk-adjusted marginal difference of 79 (same-day: 565 vs overnight 491
p = 0.81). Odds of readmission were similar between same-day and overnight stays (OR 0.18
p = 0.10). CONCLUSION: Given similar costs and readmission rates, case selection and surgeon expertise should continue to guide decision-making on same-day adrenalectomy.