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Ambulatory Surgical Centers

Written by Dr. Rieka Yu
Published on May 2, 2024
Research Highlights

Research Highlights

In MO, surgeries in ambulatory surgical centers (ASCs) are limited by the length of a patient’s stay.


MO regulates protocols for surgeries in dental offices that use deep sedation or general anesthesia, and there are no regulations for surgery offices.


Most surgeries have fewer complications in ASCs than in surgery offices.

ASCs provide surgeries that do not need an overnight stay.

In MO, surgeries are performed in hospitals, ASCs, dental offices, and surgery offices. There is no state law specifying where surgeries can take place. Under MO state code, ASCs are establishments whose primary purpose is to perform surgeries or deliver newborns (19 Mo. CSR § 30-30). ASCs have a separate license from birthing centers, are not licensed as part of a hospital, and are not used as an office or clinic for private practice.

  • The ASC must provide surgeries to at least 51% of its patients or receive at least 51% of its revenue from surgical services.
  • Under state code patients cannot stay more than 12 hours at an ASC (19 Mo. CSR § 30-30), while under MO revised statues, patients cannot stay more than 23 hours at an ASC (RsMo § 197.200).
  • MO ASCs use the definition of surgery from the American Medical Association (Schwandtner personal communication).


An ASC must have a governing body with bylaws for conducting the facility’s business (19 Mo. CSR § 30-30; Table 1). Bylaws describe the selection of medical staff members, ethical standards, and professional rules and policies for medical staff.


MO state code specifies what medical staff must be present at an ASC during a surgery (19 Mo. CSR § 30-30).

  • Only physicians, dentists, or podiatrists can perform surgeries.
  • At least one professional registered nurse (one not administering anesthesia) must be present in the operating and recovery room.
  • An anesthesiologist or physician trained in administering anesthetics can provide anesthesia services and must be present throughout the surgery.


ASCs also have requirements on surgical and safety procedures including (19 Mo. CSR § 30-30):

  • Yearly review and evaluation of surgical practices and techniques.
  • Policies and procedures for administering anesthetics and sedating drugs.
  • Rules set by the state to ensure adequate sterilization, continuity of care, patient examination, record keeping, and building construction.


Surgery and dental offices have fewer regulations than ASCs.

Office-based surgeries are those performed in an outpatient facility that is an office. The Joint Commission, the Accreditation Commission for Health Care, and the Accreditation Association for Ambulatory Health Care offer accreditation of surgery offices, however, MO has no laws or regulations for surgery offices (Federation of State Medical Boards, Schwandtner personal communication). The MO dental board has no specific rules or statutes on what surgeries can be performed in a dental office (Barnett personal communication), but they have regulations on surgeries with deep sedation or general anesthesia (20 Mo. CSR § 2110-4).

  • Dental offices must have written protocols for sedation relating to informed consent, monitoring, and emergency response.
  • Dental offices must have a minimum of three people supporting a sedated patient, one dentist and two members of the sedation team.


More generally, the operating area in a dental office must allow personnel to move freely and easily see monitors (20 Mo. CSR § 2110-4). The operating table or dental chair must allow personnel to maintain the patient’s airway, move the patient quickly, and provide a sturdy platform for CPR. The recovery area must have the necessary systems and equipment for patient monitoring, oxygen delivery, and resuscitation.


ASC surgeries tend to be safer than office-based surgeries.

Based on FL claims data, hospitalization rates within 7 days post-surgery are higher for office-based surgeries compared to ASC surgeries (Ohsfeldt et al. 2017). This comparison controls for risk factors like age or employment status. This comparison does not include dental offices.


When comparing hospitalization rates based on types of surgery, most surgery types had better outcomes in ASCs while some had no difference in outcomes between ASCs and surgery offices (Ohsfeldt et al. 2017). Procedures related to:

  • Newborn delivery and the auditory system did not differ in hospitalization rates 7 days post-surgery at ASCs and surgery offices.
  • The respiratory or cardiovascular system had higher hospitalization rates 7 days post-surgery when performed in surgery office compared to an ASC.


However, one study evaluating cosmetic surgical procedures found a lower risk of complications in surgery offices compared to ASCs (Gupta et al. 2017). This study also controlled for risk factors like age and procedure complexity.


Table 1. Regulated items in different surgery settings. Each surgery setting lists general items that are regulated by the MO Code of State Regulations. *Dental offices regulate these items for procedures that use moderate to deep sedation or general anesthesia.



19 Mo. CSR § 30-30 (2018). https://www.sos.mo.gov/cmsimages/adrules/csr/current/19csr/19c30-30.pdf.

20 Mo. CSR 2110-4 (2022). https://www.sos.mo.gov/cmsimages/adrules/csr/current/20csr/20c2110-4.pdf.

Accreditation Association for Ambulatory Health Care. (n.a.). Office-Based Surgery Centers. https://www.aaahc.org/accreditation/surgical/obs/.

Accreditation Commission for Health Care. (n.a.). Office-Based Surgery Accreditation. https://www.achc.org/office-based-surgery/.

Barnett, Brian. (2024). Personal communication. MO Department of Commerce & Insurance, Dental Board.

Federation of State Medical Boards. (2023). Office-Based Surgery (OBS). https://www.fsmb.org/siteassets/advocacy/policies/office-based-surgery-overview.pdf

Gupta V, Parkh R, Nguyen L, Afshari A, Shack B, Grotting JC, & Higdon KK. (2017). Is Office-Based Surgery Safe? Comparing Outcomes of 183,914 Aesthetic Surgical Procedures Across Different Types of Accredited Facilities. Aesthetic Surgery Journal. 27(2), 226-235. https://pubmed.ncbi.nlm.nih.gov/27553613/.

The Joint Commission. (n.a.). Office-Based Surgery Accreditation Fact Sheet. https://www.jointcommission.org/resources/news-and-multimedia/fact-sheets/facts-about-office-based-surgery-accreditation/.

Mo. Revisor § 197.200 (2017). https://revisor.mo.gov/main/OneSection.aspx?section=197.200.

Schwandtner, Waunita. (2024). Personal communication. MO Department of Health and Senior Services, Bureau of Ambulatory Care.

Ohsfeldt RL, Li P, Schneider JE, Sojanovic I, & Scheibling CM. (2017). Outcomes of Surgeries Performed in Physician Offices Compared with Ambulatory Surgery Centers and Hospital Outpatient Departments in Florida. Health Services Insights. 10, 1-21. https://journals.sagepub.com/doi/pdf/10.1177/1178632917701025.

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