An ambulatory surgery center (ASC) is a healthcare facility built specifically for surgeries that don’t require an overnight hospital stay. Patients walk in, have their procedure, and go home the same day, typically within 24 hours of admission. There are roughly 6,300 Medicare-certified ASCs operating across the United States, and that number grows by about 2% each year as more procedures shift out of traditional hospitals.
ASCs exist because many surgeries simply don’t need the full infrastructure of a hospital. A knee scope, a cataract removal, or a gallbladder surgery can be done safely in a smaller, more focused facility. The result is a streamlined experience that costs significantly less for both patients and insurers.
How ASCs Differ From Hospital Outpatient Surgery
Hospitals also perform same-day surgeries through their outpatient departments, but the experience and the price tag look very different. Hospital outpatient departments carry higher overhead costs, including emergency rooms, intensive care units, and around-the-clock staffing, and those costs get passed along. A Blue Cross Blue Shield analysis found that hospital outpatient prices for common procedures were substantially higher than ASC prices, sometimes up to five times more expensive for the same service.
The gap is also widening. Hospital outpatient prices grew by an average of 27% over the study period, compared to 11% for ASCs. For patients, this translates directly into higher copays and coinsurance. A study of Medicare recipients found that patients paid an average of $450 more out of pocket when a sports medicine procedure was done at a hospital instead of an ASC. That’s 30% to 46% higher in out-of-pocket costs for the same surgery performed by the same type of surgeon.
Overall, total costs for orthopedic procedures at ASCs ran about 40% lower than at hospitals, with facility fees (the portion charged by the building itself, separate from the surgeon’s fee) running 45% lower. Surgeon fees were essentially the same in both settings.
What Procedures Are Performed at ASCs
The range of surgeries done at ASCs has expanded considerably over the past two decades. Cataract and lens procedures are the single most common ambulatory surgery, accounting for about 8% of all major outpatient operations. Beyond eye surgery, the landscape is broad:
- Orthopedic procedures make up the largest category by volume. Seven of the top 20 ambulatory surgeries involve muscles, tendons, joints, or bones, collectively representing 22% of all major outpatient operations. This includes knee meniscus removal, knee replacements, and spinal disc procedures.
- General surgery covers gallbladder removal, hernia repair (the most common ambulatory surgery for adult men), and appendectomy.
- ENT procedures like tonsil and adenoid removal and ear tube placement are the most common ambulatory surgeries for children.
- Gynecological surgeries including hysterectomy rank among the most common procedures for younger adult women.
- Breast surgery such as lumpectomy is also routinely performed in ASCs.
- Cardiac device procedures like pacemaker insertion and replacement have moved into the ambulatory setting as well.
The trend is clearly toward more complex procedures being approved for ASC settings. Total knee replacements, for example, were only recently added to the list of surgeries eligible for ASCs, and total hip replacements have followed.
Who Owns and Operates ASCs
ASC ownership falls into a few distinct models. About 65% of ASCs are solely owned by physicians, and roughly 90% have at least some physician ownership stake. This is one of the defining characteristics of the industry: the surgeons performing the operations often have a direct financial interest in running an efficient facility.
Beyond physician-only ownership, ASCs can be joint ventures between doctors and management companies that handle the business side, or between doctors and hospital systems looking to capture outpatient volume outside their main campus. Three-way partnerships involving all three parties also exist. A newer and growing model is the hospital-owned ASC, where a health system owns the facility outright and contracts with physicians to manage clinical operations. This model is on the rise as hospitals try to compete with independent ASCs on cost and convenience.
Safety Standards and Oversight
ASCs that participate in Medicare must meet a set of federal health and safety requirements known as Conditions for Coverage. These cover several core areas: the facility must maintain a governing body with full legal responsibility for operations and quality oversight, surgical procedures must be performed by qualified physicians who have been granted privileges through a formal credentialing process, the facility must maintain infection control programs, and the building itself must meet construction and equipment safety standards. ASCs must also comply with state licensing requirements and maintain emergency preparedness plans.
Beyond federal requirements, many ASCs pursue voluntary accreditation from organizations like the Joint Commission or the Accreditation Association for Ambulatory Health Care. The Joint Commission’s program, which has been running for nearly 45 years, involves on-site surveys where inspectors assess compliance with performance standards covering patient safety, quality improvement, and care coordination. Accreditation requires the facility to demonstrate that it continuously evaluates and improves the quality of its care.
What the Experience Looks Like for Patients
If you’re scheduled for surgery at an ASC, the experience is noticeably different from a hospital visit. ASCs tend to be smaller, quieter, and more focused. You won’t be sharing the facility with emergency patients or people in intensive care. Check-in, pre-operative preparation, the procedure itself, and recovery all happen in a compact, purpose-built space.
You’ll arrive the morning of your surgery, go through pre-op steps like IV placement and anesthesia consultation, have your procedure, and then recover in a post-anesthesia area until the care team determines you’re stable enough to leave. Most patients are home within a few hours. Because ASCs handle a high volume of the same types of procedures, the staff and workflow are often highly specialized, which can mean shorter wait times and a more predictable schedule than a hospital operating room that juggles emergencies alongside planned cases.
The key limitation is that ASCs are not equipped for patients who need overnight monitoring or who have complex medical conditions that could require hospital-level intervention. If unexpected complications arise during surgery, the facility must have a transfer agreement or plan to move you to a nearby hospital. Your surgeon and anesthesiologist will evaluate beforehand whether your health status and the complexity of the procedure make an ASC appropriate for you.