How Many Ambulatory Surgery Centers are in the US?

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Ambulatory surgery centers (ASCs) are outpatient facilities that offer an alternative to hospitals for patients undergoing routine surgical procedures. Like hospitals, ASCs are regulated by state and government agencies to ensure patient safety. Many surgery centers focus on a single specialty, such as plastic surgery, orthopedics, or neurology.

Currently, there are more than 9,280 active ambulatory surgery centers in the U.S. according to Definitive Healthcare’s platform on surgery centers.

States with the Greatest Number of ASCs

  1. California: 1,213
  2. Florida: 722
  3. Texas: 710
  4. Georgia: 514
  5. Maryland: 434
  6. New York: 333
  7. New Jersey: 323
  8. Ohio: 317
  9. Arizona: 263
  10. North Carolina: 253

Fig 1 Data from Definitive Healthcare’s surgery centers platform.

How are ASCs different from hospital outpatient centers?

The primary difference between hospital outpatient departments (HOPDs) and ASCs is that hospitals offer inpatient services and overnight observation on site. This is convenient in the event of surgical complications, as patients don't have to wait for an emergency transport service. Though both facility types see low infection rates, surgery centers are also associated with lower rates of surgical site infections. Because patients recover at home, they are less likely to be exposed to bacteria and viruses from providers and other patients.

Another reason patients opt for surgery centers over hospitals is the cost. Surgery centers are often focused on a single specialty, do not include an option for overnight observation, and have lower overhead costs than hospitals, resulting in savings that are passed on to patients.

When to choose an ASC over a hospital

Though outpatient surgery centers offer convenient and often lower-cost alternatives to HOPDs, a limited number of procedures and specialties are suitable for such a setting. Every year, CMS releases its inpatient-only list: procedures that will only be reimbursed in an inpatient setting under the Hospital Outpatient Prospective Payment System due to concerns about patient safety and care outcomes.

Some of the procedures removed from the 2019 inpatient-only list include: surgical nasal and sinus endoscopies (CPT 31241), implantation or replacement of carotid sinus baroreflex device (CPT 0266T), and anesthesia for extensive spine and spinal cord procedures (CPT 00670).

Some specialties, like pain management and ophthalmology, are ideally suited to ASCs due to their ability to see large volumes of patients in a short period of time, ensuring profitability. Since 2015, the Medicare Payment Advisory Commission (MedPAC) has suggested that CMS reduce HOPD reimbursement for certain outpatient visits to encourage the shift to ASCs, where patient volumes could be more steadily maintained and HCP expectations met.

Surgery centers are also the facility of choice for patients who have few or no comorbidities. Patients likely to experience complications would probably be referred to hospital outpatient centers, where overnight monitoring and extensive specialty services are available in the event of an unforeseen circumstance.

While both ASCs and HOPDs are high-quality options for patients in need of surgical procedures, individuals may have a preference based on medical history, accessibility, cost, and other factors.

Looking to learn more about selling to physicians in an outpatient setting? Join us for our live webinar, Selling to Doctors in the Fast-Growing Outpatient Market, on May 1st at 2pm EST.

In this webinar, Enterprise Account Executive Maggie Fortune will cover how:

  • To identify ideal selling opportunities in the large ambulatory care market, including 1.6 million allied health professionals
  • Traditionally inpatient acute care environments, including cardiology, orthopedics, gynecology, and advanced dermatology, among other practice areas, are shifting
  • Payment reforms, technology advancement, and patient sentiment are driving change in the ambulatory care market
  • To target the key physician influencers across multiple facilities and networks

Save your seat today!


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