The recent death of comedienne Joan Rivers, which followed a cardiac arrest during a routine throat procedure, has brought national attention to the potential safety hazards of office-based procedural anesthesia. This retrospective study examined adverse events associated with moderate procedural sedation performed outside of the operating room at a tertiary medical center. Adverse events were relatively rare, with only 52 safety incidents identified out of more than 140,000 cases over an 8-year period. The most common harm was oversedation leading to apnea and requiring the use of reversal agents or prolonged bag-mask ventilation. Women were found to be at particularly increased risk for adverse events including oversedation and hypotension. These findings suggest that a combination of patient and procedural characteristics may help risk stratify patients, allowing for appropriate responses such as increased monitoring and staffing for patients likely to experience sedation-related complications. A previous AHRQ WebM&M perspective described office-based anesthesia as the "Wild West" of patient safety.