Disclaimer: This article is intended solely for informational and educational purposes only. It does not constitute medical advice.
Over the past decade, ambulatory surgery has become a predominant mode of surgery across many specialties. Procedures once considered strictly inpatient have steadily migrated into into ambulatory surgery centers (ASCs) and even office-based surgery (OBS) settings, with the ASC market projected to expand at roughly 4% annually between 2017 and 2027, and total outpatient case volume estimated to approach 144 million procedures in 2023 (Young et al., 2023). Orthopedics, ophthalmology, gastroenterology, vascular surgery, gynecology, and interventional radiology have all seen substantial volume transferred from the hospital to ambulatory surgery settings, driven largely by cost differentials between hospital outpatient departments, ASCs, and physician offices. These trends in ambulatory surgery are expected to continue driving growth (Young et al., 2023).
Cost and readmission data support the rationale behind this shift. In an analysis of over 73,000 patients undergoing hernia repair, thyroidectomy, laparoscopic cholecystectomy, or laparoscopic appendectomy, adjusted surgical costs were significantly lower for ambulatory cases across all four procedure types, and 30-day readmission rates were equal or lower in the ambulatory setting for three of the four procedures studied (Friedlander et al., 2019). Notably, cost savings were not offset by higher downstream acute-care spending, suggesting that the ambulatory shift represents a genuine efficiency gain rather than cost-shifting to readmissions (Friedlander et al., 2019).
These ambulatory surgery trends are not isolated to the U.S. A nationwide Japanese claims analysis found that outpatient rates for eyelid, strabismus, glaucoma, vitreoretinal, and cataract surgery all rose significantly between the pre- and post-COVID periods, with the largest absolute increases in glaucoma and cataract procedures (Kabata et al., 2026).
Notably, the shift persisted well beyond the acute phase of the pandemic, indicating a structural rather than transient change in practice patterns, though regional disparities emerged, with vitreoretinal surgery showing a significantly larger outpatient increase in metropolitan prefectures over non-metropolitan ones (Kabata et al., 2026). Complementary U.S. claims data similarly found that outpatient surgical growth continued at roughly 6% annually even after the initial pandemic-era surge subsided, particularly in orthopedics, ophthalmology, and gastroenterology (Stark, 2026).
However, the expansion of ambulatory surgery has not occurred equitably. The same U.S. analysis found that patients in lower-income areas experienced a 6% decline in outpatient procedure volume, while those in higher-income areas saw a 5.2% increase, even as total joint replacement costs fell by $6,000 to $7,000 per case with the shift to outpatient settings (Stark, 2026). Cost savings largely accrued to payers and systems rather than patients, as out-of-pocket costs remained largely unchanged (Stark, 2026).
The expanding scope of ambulatory surgery has also changed the acuity of patients treated in these settings. Data show trends toward higher ASA physical status patients and more complex surgeries being performed outside the hospital, necessitating greater attention to patient selection, facility capability, and emergency preparedness at ambulatory centers (Young et al., 2023). This concern echoes an analysis that found that while ambulatory anesthesia was infrequently associated with adverse outcomes, evidence supporting management decisions for specific high-risk populations—including the elderly, heart transplant recipients, and patients with obstructive sleep apnea—remained generally of low quality, with few prospective trials available to guide care (Bryson et al., 2004).
Trends in surgery volume, procedural settings, and patient demographics reveal a multi-specialty transition toward ambulatory surgical care that has proven durable, cost-effective, and clinically comparable to inpatient care for well-selected patients, while also revealing persistent gaps in regional access, socioeconomic equity, and prospective safety evidence for higher-risk populations.
References
- Bryson, G. L., Chung, F., Finegan, B. A., Friedman, Z., Miller, D. R., van Vlymen, J., Cox, R. G., Crowe, M.-J., Fuller, J., & Henderson, C. (2004). Patient selection in ambulatory anesthesia – An evidence-based review: part I. Canadian Journal of Anesthesia, 51(8), 768–781. https://doi.org/10.1007/BF03018434
- Friedlander, D. F., Krimphove, M. J., Cole, A. P., Marchese, M., Lipsitz, S. R., Weissman, J. S., Schoenfeld, A. J., Ortega, G., & Trinh, Q.-D. (2019). Where is the value in ambulatory versus inpatient surgery? Annals of Surgery. https://doi.org/10.1097/SLA.0000000000003578
- Kabata, Y., Hayashi, I., Terauchi, R., & Nakano, T. (2026). Nationwide trends in outpatient rates for ophthalmic surgeries in Japan before and after the COVID-19 pandemic: an analysis of the NDB open data. Scientific Reports. https://doi.org/10.1038/s41598-026-61094-5
- Stark, K. (2026, April 23). Outpatient surgeries still grew after COVID, reshaping care. Penn LDI Research & Policy Updates. https://ldi.upenn.edu/our-work/research-updates/outpatient-surgeries-still-grew-after-covid-reshaping-care/
- Young, S., Osman, B., & Shapiro, F. E. (2023). Safety considerations with the current ambulatory trends: more complicated procedures and more complicated patients. Korean Journal of Anesthesiology, 76(5), 400–412. https://doi.org/10.4097/kja.23078