The Healthcare Cost and Utilization Project (HCUP) Nationwide Ambulatory Surgery Sample (NASS) featuring 2019 data is now available. The NASS is the largest all-payer ambulatory surgery database in the country. Unweighted, it contains approximately 9.0 million major ambulatory surgery encounters. Weighted, the NASS estimates approximately 11.9 million major ambulatory surgery encounters in the United States.

Constructed from the State Ambulatory Surgery and Services Databases (SASD) and State Emergency Department Databases (SEDD), the NASS tracks information about major ambulatory surgery encounters in hospital-owned facilities across the United States. The database provides information on patient characteristics, clinical diagnostic and surgical procedure codes, disposition of patients, total charges, expected source of payment, and facility characteristics. Major ambulatory surgeries are defined as selected invasive, therapeutic surgical procedures that typically require the use of an operating room and require regional anesthesia, general anesthesia, or sedation. Procedures intended primarily for diagnostic purposes are excluded. Beginning with the 2019 data year, the NASS now includes information on patient race and ethnicity.

The 2019 NASS can be purchased through the HCUP Central Distributor. Additional information is located on the NASS Overview Page.