What is the relative frequency of uncommon ambulatory surgery procedures performed in the United States with an anesthesia provider?

Between 1994 and 1996, the National Center for Health Statistics used sophisticated sampling methods to measure the number and types of ambulatory surgery cases performed in the United States, We reanalyzed raw data obtained from this National Survey of Ambulatory Surgery to select cases with an anesthesia provider and here report characteristics of these 228,332 cases (e.g., patient age, anesthetic type). The goal of our study was to estimate what percentage of cases, of a specified surgical procedure or combination of procedures, may have been performed less than once per year per facility. Previous studies suggest the most important source of scheduling inaccuracy can be the absence of recently performed cases on which to base predictions of case duration. We found that 36% +/- 1% (SE) of all cases in the United States were a type of procedure or combination of procedures that occurred <6984 times per year (the number of surgery facilities performing ambulatory surgery in the United States). Approximately one third of all ambulatory cases were of a procedure or combination of procedures that may have been performed as infrequently as once per year per facility. This could impair the effectiveness of predicting the durations of ambulatory cases by using historical case-duration data.