ASC stands for ambulatory surgery center, a healthcare facility designed specifically for surgeries that don’t require an overnight hospital stay. These centers handle procedures where patients arrive, have surgery, and go home the same day, typically within 24 hours. As of 2023, there are over 6,300 Medicare-certified ASCs operating across the United States, and that number continues to grow.
How ASCs Differ From Hospitals
An ambulatory surgery center operates exclusively for outpatient surgical procedures. Unlike a hospital outpatient department (HOPD), which is attached to a full hospital campus with emergency rooms, intensive care units, and inpatient beds, an ASC is a standalone or independent facility focused on scheduled surgeries for patients who are expected to recover at home.
This streamlined setup is the key difference. ASCs don’t maintain the infrastructure of a full hospital, which means lower overhead costs. Those savings get passed along in a significant way. A colonoscopy with biopsy costs about $1,766 total at a hospital outpatient department but roughly $1,089 at an ASC. Hernia repair drops from $5,228 to $3,003. Cataract removal goes from $3,727 to $2,410. Depending on the procedure, patients and insurers save between 35 and 46 percent by using an ASC instead of a hospital setting. The doctor’s fee stays the same in both locations; the difference comes entirely from the facility charge.
What Procedures Are Performed at ASCs
ASCs cover a broad range of surgical specialties. The most common procedure is cataract removal, which accounts for about 8 percent of all major ambulatory surgeries. Musculoskeletal surgeries, including tendon repairs, joint procedures, knee arthroscopy, and knee replacement, make up roughly 22 percent of the total volume. Gastrointestinal procedures like gallbladder removal, hernia repair, and appendectomy account for another 12 percent.
Other frequently performed surgeries include:
- Ear, nose, and throat: tonsil and adenoid removal, ear tube insertion
- Gynecology: hysterectomy
- Breast surgery: lumpectomy
- Spine: disc removal and decompression procedures
- Cardiac: pacemaker insertion or replacement
- Nerve: carpal tunnel and other peripheral nerve decompression
The list of approved procedures keeps expanding. In January 2025, CMS added 32 new separately payable procedures to the ASC-covered list, along with 33 procedures that were previously bundled or non-payable, including 19 dental procedures. A new code for implanting a medical knee shock absorber was also introduced. The trend is toward shifting more complex surgeries into ASCs as surgical techniques and anesthesia improve.
Who Owns and Operates ASCs
Many ASCs are fully or partially owned by the surgeons who operate in them. This physician-ownership model is one of the defining features of the ASC industry. Federal regulations require ASCs to disclose in writing which physicians have a financial interest or ownership stake in the facility. Some ASCs are also owned by larger healthcare corporations or hospital systems, and joint ventures between physician groups and corporate partners are common.
Physician ownership creates an incentive structure where the doctors performing surgeries also have a stake in running the facility efficiently. Critics sometimes raise concerns about potential conflicts of interest, since a surgeon-owner might benefit financially from steering patients to their own facility. The disclosure requirement exists specifically to give patients transparency about those relationships.
Safety Standards and Accreditation
To participate in Medicare, an ASC must meet federal “Conditions for Coverage,” a set of standards covering patient safety, infection control, staffing, and emergency protocols. ASCs can earn Medicare certification through accreditation by organizations like The Joint Commission, which is designated by CMS as an approved accreditor for ambulatory surgery centers.
The accreditation survey process is hands-on. Surveyors review surgical case logs from the previous six months, examine records of any patients who needed hospital transfers or who died during a procedure in the past year, and evaluate the facility’s infection control program. ASCs that fail to maintain compliance risk losing their Medicare certification, which for most facilities would mean closing their doors.
What the Experience Looks Like for Patients
If your surgeon schedules you for a procedure at an ASC, the experience is more streamlined than a hospital visit. You’ll typically arrive a couple of hours before your surgery, go through pre-operative preparation including anesthesia review, have your procedure, and spend time in a recovery area until the care team determines you’re stable enough to go home. The entire visit usually lasts a few hours.
You’ll need someone to drive you home, since most procedures involve sedation or general anesthesia. Recovery instructions, pain management plans, and follow-up appointments are provided before discharge. Because ASCs are not equipped for overnight stays, any unexpected complication requiring extended monitoring means a transfer to a nearby hospital. This is rare, but it’s one reason ASCs are selective about which patients and procedures they take on. Patients with serious underlying health conditions or those undergoing high-risk surgeries are generally better served in a hospital setting where intensive care is immediately available.
Why ASCs Are Growing
The number of Medicare-certified ASCs grew 2.5 percent from 2022 to 2023 alone, reaching 6,308 facilities. Several forces are driving this expansion. The cost savings are substantial: MedPAC estimated that adopting site-neutral payment policies (paying the same rate regardless of where a procedure is performed) would reduce Medicare spending and patient cost-sharing by $7.7 billion. Even shifting just 5 percent of cataract surgeries from hospitals to ASCs could save roughly $260 million annually.
Advances in minimally invasive surgery and anesthesia have also made it safe to perform increasingly complex procedures without an overnight stay. Procedures like total knee replacements that once required days in the hospital now routinely happen in ASCs. As CMS continues adding procedures to the approved list, the scope of what ASCs can handle will keep expanding, and more patients will encounter these facilities as part of their surgical care.