The Rise of Ambulatory Surgery Centers: What 2023–2025 Market Data Reveals About the Future of American Surgery

Executive Summary

The center of gravity in American surgery continues to move from inpatient hospital units toward ambulatory surgery centers (ASCs). Medicare data published by the Medicare Payment Advisory Commission (MedPAC) show an ASC sector growing steadily rather than explosively: the number of Medicare-certified ASCs reached 6,436 in 2024, Medicare ASC payments reached $7.5 billion, and surgical procedures per fee-for-service (FFS) beneficiary rose for a second consecutive year.

The more consequential change is regulatory. For calendar year 2026, CMS added roughly 550 to 560 procedure codes to the ASC Covered Procedures List (CPL) and began a three-year phase-out of the inpatient-only (IPO) list. That single-year expansion is nearly nine times the 62 codes added across 2023, 2024, and 2025 combined.

This analysis separates what has happened (2023–2024 actual results), what has not yet been measured (2025 Medicare results, which MedPAC will report in its March 2027 report to Congress), and what remains a forecast (the effect of the 2026 policy changes).

The Structural Shift: From Inpatient Units to Ambulatory Settings

For most of the modern era, the hospital was the default site of surgery. That default is eroding. MedPAC attributes the long-term growth of ASCs to changes in clinical practice and health care technology that have expanded the range of procedures performed in ambulatory settings, together with practical advantages for patients, physicians, and the Medicare program (MedPAC, 2025; MedPAC, 2026).

The transformation is operating on three levels at once:

• Clinical. Procedures that once required admission are increasingly performed with same-day discharge. MedPAC notes that knee and hip arthroplasty have grown in ASC volume since CMS made them ASC-covered services.
• Economic. Medicare pays ASCs substantially less than hospital outpatient departments (HOPDs) for the same service, lowering costs for the program and for beneficiaries.
• Regulatory. CMS determines which procedures Medicare will pay for in an ASC. For 2026, that list expanded more than in any of the three preceding years by an order of magnitude.

One caveat shapes every number in this article. MedPAC’s ASC analysis covers Traditional (fee-for-service) Medicare only. As Medicare Advantage enrollment has grown, the FFS Part B population fell from 28.6 million in 2023 to 27.9 million in 2024, so aggregate FFS volume understates total ASC activity. Per-beneficiary measures are the more reliable indicator of the underlying trend (MedPAC, 2026).

ASC Market Growth: 2023–2025

The table below consolidates MedPAC’s most recent published figures. The 2023 values are MedPAC’s revised figures from its March 2026 report; 2025 Medicare results have not yet been published.

Sources: MedPAC, March 2026 Report, Chapter 11, Tables 11-1, 11-4, and 11-8; MedPAC, March 2025 Report, Chapter 10. The 2023 growth rate is calculated from MedPAC’s revised facility counts.

A note on revisions. When MedPAC first reported 2023 results in March 2025, it counted 6,308 ASCs, 250 openings, 95 closures, a net gain of 155 facilities, 2.5% growth, and $6.8 billion in payments. Its March 2026 report revised those to the values above, noting that figures can differ from prior years because of methodological changes and data updates. Readers comparing sources should expect small differences of this kind.

Medicare ASC indicators, 2024 vs. 2023

Traditional (fee-for-service) Medicare only

Medicare-certified ASCs6,436from 6,296 · +2.2%

FFS Medicare ASC payments$7.5Bfrom $6.6B · +13.0%

Services per 1,000 FFS beneficiaries229.9from 222.1 · +3.5%

Payments per FFS beneficiary$268from $231

Three patterns stand out. First, facility growth is steady rather than accelerating: roughly 250 openings a year against 100 or so closures and mergers. Second, utilization per beneficiary is rising even as the FFS population shrinks, which is why total FFS volume held flat at 6.4 million services. Third, spending is growing much faster than volume. MedPAC attributes the 13.0% increase in 2024 payments mainly to an 8.4% rise in the average relative weight of services provided, alongside a 3.2% conversion-factor update and a 0.8% increase in per-capita volume. In other words, ASCs are taking on more resource-intensive procedures, not simply more procedures.

Medicare ASC Covered Procedures List Expansion: 2023–2026

The ASC Covered Procedures List (CPL) defines which procedures Medicare will pay for in an ASC. Each year’s OPPS/ASC final rule sets the changes. The figures below are taken from the executive summaries of those final rules; the 2026 counts are regulatory announcements effective January 1, 2026, not measured utilization.

Sources: CMS OPPS/ASC final rules for CY 2023 (FR Doc. 2022-23918), CY 2024 (2023-24293), CY 2025 (2024-25521), and CY 2026 (2025-20907); CMS CY 2026 final rule fact sheet; MedPAC, March 2026 Report, Chapter 11.

Codes added to the Medicare ASC Covered Procedures List, by year

2026 is a regulatory announcement, not measured utilization

• 20234CY 2023 · 4 codes added
• 202437CY 2024 · 37 surgical procedures
• 202521CY 2025 · 21 medical and dental procedures
• 2026547–560CY 2026 · 547 (final rule) to 560 (fact sheet)

Codes added (final rule text)Additional codes in CMS fact sheet

What changed in 2026. CMS revised the ASC CPL criteria at § 416.166, modifying the general standard criteria and converting five general exclusion criteria into nonbinding “physician considerations for patient safety.” In practice, this shifts more of the site-of-service judgment to the treating physician. Separately, CMS began phasing out the inpatient-only (IPO) list over three years, starting January 1, 2026 and ending January 1, 2029, removing 285 mostly musculoskeletal services from the IPO list for 2026 and adding 271 of them to the ASC CPL.

Reconciling 547 and 560. The two figures come from two CMS documents. The final rule’s executive summary states that CMS added 276 procedures under the revised criteria plus 271 codes removed from the IPO list, for 547. CMS’s fact sheet for the same rule states 289 procedures under the revised criteria plus the same 271, for 560. MedPAC’s March 2026 report uses the 276 figure. Neither document explains the 13-code difference; the definitive code-level list is the final rule’s ASC addenda. The Ambulatory Surgery Center Association’s detailed regulatory analysis is available to members only and was not reviewed for this article, so readers citing association figures should confirm which CMS count they rely on.

Why Surgery Is Moving From Hospitals to ASCs: Five Drivers

1. Cost savings and reimbursement economics. Medicare pays ASCs less than HOPDs for every service covered in both settings; for most services, ASC payment rates are about 46% lower (MedPAC, 2026). For 2026, the ASC conversion factor is $56.32, compared with $90.97 under the OPPS. Lower rates reduce both program spending and beneficiary cost sharing. One important limitation: Medicare does not require ASCs to report cost data, so their margins cannot be measured directly. MedPAC has repeatedly recommended that Congress require ASC cost reporting, most recently in 2024 and 2025.

2. Advances in anesthesia and minimally invasive surgery. MedPAC identifies changes in clinical practice and health care technology as a primary reason surgical procedures have moved into ambulatory settings. The data point the same way: the 8.4% rise in the average relative weight of ASC services in 2024 indicates more resource-intensive cases, and CMS’s 2026 additions include laparoscopic procedures, laminectomy, and arthroplasty revisions. National data that isolate the specific contribution of anesthetic technique are limited, so this driver is best described qualitatively.

3. CMS policy and expanded outpatient eligibility. Medicare coverage policy is the gatekeeper for ASC growth in the Medicare population. The 2026 rule both widened the CPL criteria and began dismantling the IPO list. MedPAC is cautious about the near-term effect, noting that the extent to which eliminating the IPO list will expand ASC volume “is not clear,” because ASCs have generally performed low quantities of these procedures. Knee and hip arthroplasty are the notable exceptions.

4. Physician autonomy and operational efficiency. According to MedPAC, ASCs allow surgeons to customize their surgical environment and hire specialized staff, enabling more procedures in the same amount of time than in an HOPD. MedPAC also cites research showing shorter nonoperative times in ASCs (Imran et al., 2019). The model favors focus: in 2024, 68% of ASCs billing Medicare specialized in a single clinical area, more than 95% were for-profit, and about 94% were located in urban areas.

5. Patient convenience and same-day recovery. For patients, MedPAC lists more convenient locations, shorter waiting times, lower cost sharing, and easier scheduling relative to HOPDs. In 2024, 3.4 million FFS Medicare beneficiaries received ASC care. Quality evidence is more mixed: MedPAC reports that performance on ASC Quality Reporting Program measures was mixed in 2024, and notes that the claims-based outcome measures exclude many common ASC services, such as eye procedures and pain management.

Surgical Specialties Driving ASC Growth

MedPAC classifies the 5,803 ASCs that billed FFS Medicare in 2024 by specialty. The comparison below pairs those counts with the specialty signals in CMS’s recent CPL decisions.

Source: MedPAC, March 2026 Report, Chapter 11, Table 11-3; CMS CY 2024 and CY 2026 OPPS/ASC final rules.

The established core remains gastroenterology, ophthalmology, and pain management, which together account for more than half of Medicare-billing ASCs. Growth at the margin is coming from orthopedics, particularly in multispecialty centers that combine orthopedics with pain management, and from cardiology. Spine and cardiovascular procedures are the most visible beneficiaries of the 2026 eligibility changes, although neither yet appears as a large standalone ASC category in Medicare data.

Volume also remains highly concentrated. In 2024, half of ASC surgical volume for FFS beneficiaries came from seven procedures, half of FFS Medicare ASC revenue came from twelve, and the 20 most frequent services accounted for about 68% of volume (MedPAC, 2026). The new eligibility rules widen what ASCs may do; whether they change this concentration is an open question.

Strategic Market Outlook for 2026

The 2026 policy changes took effect on January 1, 2026, but their market effects will not appear in Medicare data for some time. MedPAC’s report on 2025 results is due in March 2027, and 2026 utilization will follow after that. The table below separates what is established from what is the author’s analysis.

MedPAC also flags a structural risk. Because ASCs can select their patients, a growing ASC sector may capture a larger share of the more profitable ambulatory procedures, leaving less profitable cases in hospital outpatient departments. How CMS, hospitals, and payers respond to that dynamic is one of the most important questions for the next several years.

Executive Conclusion

The 2023–2024 data describe a mature, steadily growing sector: roughly 140 to 150 net new Medicare-certified ASCs a year, rising utilization per beneficiary, and Medicare payments growing faster than volume as case mix shifts toward more complex procedures. The 2026 rule changes the slope of the opportunity, not yet the results. For the first time in years, the binding constraint on ASC growth in Medicare is less about what CMS permits and more about what ASCs are prepared to deliver safely and economically.

For each stakeholder, the implications differ:

• Healthcare executives and investors should treat 2026 as the start of a multi-year transition, measured against MedPAC’s 2025 and 2026 data as they are published, rather than as an immediate volume event.
• Hospitals should expect continued migration of elective outpatient volume, most acutely in orthopedics and spine, and evaluate joint ventures or their own ambulatory capacity accordingly.
• Physicians gain broader latitude to choose the site of service, along with greater responsibility for documenting patient selection under the new safety considerations.
• ASC operators face higher-acuity cases that demand stronger clinical protocols, recovery capacity, and cost management, without the benefit of Medicare cost reporting to benchmark against.
• Healthcare technology companies will find growing demand for tools that support perioperative documentation, device data capture, interoperability with hospital and payer systems, and operational analytics in settings without large IT departments.

The shift of American surgery toward ambulatory settings is not a forecast. It is visible in Medicare data year after year. What 2026 changes is its potential scale, and the organizations that prepare their clinical and operational infrastructure now will be best positioned as the data catch up.

Methodology and Data Notes

• Actual results are MedPAC’s published figures for 2023 and 2024. They cover Traditional (fee-for-service) Medicare only and exclude Medicare Advantage enrollees, so aggregate volumes understate total ASC activity.
• 2023 values use MedPAC’s revised March 2026 figures. MedPAC’s first-reported 2023 values (March 2025) are noted in the market growth section. The 2023 facility growth rate is calculated from MedPAC’s revised counts.
• 2025 Medicare results had not been published as of this article’s date. No estimates have been substituted.
• Regulatory figures for the Covered Procedures List come from the executive summaries of CMS’s OPPS/ASC final rules and, for 2026, CMS’s final rule fact sheet. Removals are listed as “none reported” where the rule summaries report additions only.
• Peer-reviewed findings (Imran et al., 2019; Courtemanche and Plotzke, 2010; Hollenbeck et al.) are cited as summarized by MedPAC.
• ASCA reporting on the 2026 rule is available to association members only and was not reviewed.
• Outlook statements in the 2026 section are the author’s analysis and are labeled as such.

References

1. Medicare Payment Advisory Commission. (2026). Ambulatory surgical center services: Status report (Chapter 11). March 2026 Report to the Congress: Medicare Payment Policy. Chapter PDF · Report page
2. Medicare Payment Advisory Commission. (2025). Ambulatory surgical center services: Status report (Chapter 10). March 2025 Report to the Congress: Medicare Payment Policy. Chapter PDF · Report page
3. Centers for Medicare & Medicaid Services. (2022, November 23). CY 2023 Hospital Outpatient Prospective Payment and Ambulatory Surgical Center Payment Systems final rule with comment period. Federal Register, FR Doc. 2022-23918. federalregister.gov/d/2022-23918
4. Centers for Medicare & Medicaid Services. (2023, November 22). CY 2024 OPPS/ASC final rule with comment period. Federal Register, FR Doc. 2023-24293. federalregister.gov/d/2023-24293
5. Centers for Medicare & Medicaid Services. (2024, November 27). CY 2025 OPPS/ASC final rule with comment period. Federal Register, FR Doc. 2024-25521. federalregister.gov/d/2024-25521
6. Centers for Medicare & Medicaid Services. (2025, November 25). CY 2026 OPPS/ASC final rule with comment period. Federal Register, FR Doc. 2025-20907. federalregister.gov/d/2025-20907
7. Centers for Medicare & Medicaid Services. (2025, November 21). Calendar Year 2026 Hospital Outpatient Prospective Payment System (OPPS) and Ambulatory Surgical Center (ASC) Payment System Final Rule [Fact sheet]. cms.gov fact sheet
8. Imran et al. (2019); Courtemanche and Plotzke (2010); Hollenbeck et al. As cited in MedPAC (2026), Chapter 11; full citations appear in that chapter’s reference list.