An ambulatory surgical center (ASC) is a facility for same-day surgery — you have the procedure and go home without an overnight hospital stay. CMS lists 5,611 Medicare-certified ASCs across 54 states, each measured on the federal ASC quality measures.
What an ambulatory surgical center is
An ambulatory surgical center is built for one job: planned, lower-risk procedures on patients who are healthy enough to recover at home the same day. “Ambulatory” means the patient walks in and walks out. Common ASC procedures include cataract surgery, colonoscopies and endoscopies, joint and pain injections, and many orthopedic, ENT, and podiatry procedures.
ASCs grew out of a simple idea: a facility purpose-built for outpatient surgery can be safer and far cheaper for routine procedures than a full hospital operating room. Because they are narrowly scoped, they are also easier to measure — which is why CMS tracks them as their own facility type.
ASC vs. hospital outpatient department
- Same-day procedures only — no overnight stay
- Specialized, smaller, lower-cost setting
- No emergency or inpatient services
- Reports the ASC quality measures to CMS
- Part of a hospital with inpatient capacity
- Handles higher-acuity and emergency cases
- Typically higher facility fees for the same procedure
- Reports under the hospital’s CMS measures
How ASC quality is measured
CMS publishes a dedicated set of ambulatory surgical center quality measures, labeled ASC-1 through ASC-12. They track patient-safety events and outcomes — patient falls, burns, wrong-site or wrong-side surgery, and whether a patient had to be transferred or admitted to a hospital after an outpatient procedure. Together they let a patient compare same-day surgery facilities on what actually happened to patients, not on advertising. Fonteum surfaces these measures per facility, each stamped with its CMS source and snapshot date.
Ambulatory surgical centers in the US
The CMS file lists 5,611 Medicare-certified ambulatory surgical centers across 54 states and territories. Notably, all 5,611 of them carry a National Provider Identifier — making ASCs the Care Compare facility type with the most complete NPI coverage, and the cleanest to join to the rest of the federal provider graph.
US ambulatory surgical centers by the numbers
Find an ambulatory surgical center
Browse loaded Medicare-certified ASCs by state with available CMS quality measures. Supported fields display available CMS source and snapshot metadata.
ASC compare →Frequently asked questions
- What is an ambulatory surgical center?
- An ambulatory surgical center (ASC) is a healthcare facility where patients have surgery or procedures and go home the same day, without an overnight hospital stay. ASCs handle planned, lower-risk procedures — cataract surgery, colonoscopies, joint injections, and many orthopedic and ENT procedures — in a setting built specifically for outpatient care.
- What is the difference between an ASC and a hospital?
- A hospital admits patients overnight and handles emergencies and complex inpatient care; an ASC is limited to same-day procedures on patients well enough to recover at home. ASCs are typically smaller, more specialized, and lower-cost for the same procedure, but they do not provide emergency or inpatient services.
- How many ambulatory surgical centers are there in the US?
- The CMS Care Compare ambulatory surgical center file lists 5,611 Medicare-certified ASCs across 54 states and territories. Every one carries a National Provider Identifier, making ASCs the Care Compare facility type with the most complete NPI coverage.
- How is ASC quality measured?
- CMS publishes a set of ASC quality measures (labeled ASC-1 through ASC-12) covering patient safety events such as falls, burns, wrong-site surgery, and hospital transfers or admissions after a procedure. These let patients and researchers compare outpatient surgery facilities on outcomes, not marketing.
- Are ambulatory surgical centers Medicare-certified?
- Most ASCs that bill Medicare are Medicare-certified and carry a CMS Certification Number (CCN), which is the federal key that links them across CMS files. Certification means the facility met federal conditions for coverage and is subject to CMS quality reporting.
- How can I look up an ambulatory surgical center?
- Fonteum's ASC compare pages list loaded Medicare-certified ambulatory surgical centers by state with available CMS quality measures. Supported fields display the available CMS source and snapshot date. You can also look up a facility by its NPI where one is published and screen that NPI against the OIG exclusion list.
Related
- Ambulatory surgical center quality data — per-facility CMS quality measures by state.
- ASC glossary entry — the short definition and where the term fits in the data graph.
- What is a CCN (CMS Certification Number)? — the federal key that ties an ASC across CMS files.
- Skilled nursing facilities explained — another Medicare-certified facility type with CMS quality data.
- Compare loaded CMS Care Compare facilities — ASCs, nursing homes, home health, hospice, dialysis, and more.
- Look up a facility by NPI — search any provider or organization and check its federal records.