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What is an ambulatory surgical center?

An ambulatory surgical center (ASC) is a Medicare-certified facility that performs surgical procedures on patients who do not need overnight hospitalization — commonly cataract surgery, colonoscopies, and orthopedic procedures. CMS certifies ASCs under Conditions for Coverage, pays them under the ASC Payment System, and publishes quality data for over 5,600 certified ASCs on Care Compare.

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Full name: Ambulatory Surgical Center (ASC)

Short explanation

An Ambulatory Surgical Center (ASC) is a Medicare-certified health care facility that provides surgical services to patients who do not require hospitalization. CMS certifies ASCs under Conditions for Coverage and reimburses them under the ASC Payment System. CMS publishes quality and performance data for over 5,600 Medicare-certified ASCs through the Care Compare ASC dataset. Common ASC procedures include cataract surgery, colonoscopies, and orthopedic procedures. ASCs collectively perform more than 23 million procedures annually in the United States.

Last updated: 2026-07-11Reviewed by: Dr. Jennifer Montecillo, MDGullas College of Medicine, 2019. Non-practicing medical reviewer.

How it’s used

  • CMS Care Compare — ASC Quality Measures: ASC quality measures including complication and unplanned hospital transfer rates are published through Care Compare, drawn from the CMS Care Compare ASC dataset.
  • CMS Provider of Services (POS) file: ASCs are certified facilities keyed by CCN in the POS file, the identity backbone Fonteum uses to join ASC quality to enrollment data.
  • CMS ASC Payment System: Medicare reimburses ASCs under a distinct payment system, and the roughly 5,600 certified ASCs are the population Fonteum's ASC dataset covers.

Frequently asked questions

What is an ambulatory surgical center?
An ASC (Ambulatory Surgical Center) is a Medicare-certified facility that performs same-day surgical procedures on patients who do not require overnight hospitalization.
How does CMS pay ASCs?
CMS pays Medicare-certified ASCs under the ASC Payment System, a prospective payment based on ambulatory payment classification (APC) groupings.
How many ASCs participate in Medicare?
Over 5,600 ASCs are certified to participate in Medicare as of 2024.

What’s on file, by the numbers

Platform snapshot · 2026-08-30

13.4Mproviders & companiesProviders, organizations, owners, and facilities on file
26.2Msource-linked factsSource-linked field facts in the dated platform snapshot
90sources with dataDistinct snapshot source IDs with at least one positive record count
16fresh sourcesDistinct source IDs whose latest positive-data snapshot falls within the preceding 45 days
111sources integratedActive registry rows; integration does not establish a load
13state Medicaid jurisdictionsDistinct states represented in the state-exclusions serving table

Integrated, with-data, and fresh-observation counts are separate. No platform-wide source-completeness count is published. Completeness is source-specific and must be evaluated against the named source's expected scope. State coverage is a separate jurisdiction measure.

Source authority is record-specific

Use the issuer named on the record.

Fonteum spans federal, state, and global public publishers. A source page or returned record identifies its issuer and dataset where that metadata is available. A platform registry count does not assign every page to one authority or establish loaded, fresh, or complete coverage.

Browse source records and their stated limitations →

Reproducible by design

Inspect the evidence each published figure actually supplies.

Source and date

Research pages expose the named public file and observation date where those fields are available. Source-file SHA-256 coverage is separate; facts do not currently link deterministically to signatures.

Available derivation

Studies with a retained release and committed derivation link the SQL or method used. Other studies state the evidence and reproduction limits they actually have.

Daily observations

Dated table row-count observations can detect local drift. They do not imply that an upstream publisher released or Fonteum ingested new data that day.

Named medical review

Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

Read the full provenance and attestation methodology →

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