In 2012, AHRQ researchers collaborated with an expert medical coder and a general surgeon to develop specifications for two surgery flags that were narrowly defined and broadly defined. These two data elements (HCUP_SURGERY_NARROW and HCUP_SURGERY_BROAD) are included in the HCUP state databases beginning in 2011 and replace the previous ambulatory surgery flag HCUP_AS.

The narrowly defined flag (HCUP_SURGERY_NARROW) is the most targeted and restrictive identifier, consisting of invasive surgical procedures. An invasive therapeutic surgical procedure is defined as involving incision, excision, manipulation, or suturing of tissue that penetrates or breaks the skin; typically requires use of an operating room; and also requires regional anesthesia, general anesthesia, or sedation to control pain.

The broadly defined flag (HCUP_SURGERY_BROAD) identifies procedures identified by the narrow flag as well as other procedures that occur in ambulatory surgery settings that may not fit the strict definition of surgery. This definition includes invasive therapeutic or diagnostic surgical procedures involving incision, excision, manipulation, or suturing of tissue that penetrates or breaks the skin or enters a body cavity; typically requires use of an operating room; and also typically requires regional anesthesia, general anesthesia, or sedation to control pain. This includes percutaneous procedures and all "open" surgical procedures, regardless of therapeutic or diagnostic purpose.

The surgery flags are designed to be setting-agnostic, meaning that they could be applied to either an inpatient or outpatient setting. The rationale for this approach is that surgeries now performed in an inpatient setting may become more prevalent in an outpatient setting in the future. If they are applied to the inpatient setting, then inpatient surgeries are identified. If they are applied to the outpatient setting, then outpatient surgeries are identified. These flags are based on ICD-9-CM and CPT procedure codes and do not depend on assignment of revenue codes or other administrative data elements. The detailed specifications incorporated the classifications of surgery codes developed by Alan Simon and colleagues¹ and by the HCUP procedure class software.

¹ Weiser, T., Semel, A., Simon, A., et. al. (2011) In-hospital Death following Inpatient Surgical Procedures in the United States, 1996-2006. World Journal of Surgery. Vol. 35, No. 9, pp. 1950-1956.