Impact of Office-Based Nitrous Oxide on Operating Room Utilization for Endometrial Sampling

To evaluate the association between nitrous oxide analgesia availability and the proportion of endometrial sampling procedures (endometrial biopsies, dilation and curettages, and hysteroscopies) performed in the office versus the operating room.

Retrospective observational cohort study SETTING: Community-based integrated healthcare system PARTICIPANTS: 1,803 patients who underwent endometrial sampling between March 2023 and January 2025 INTERVENTIONS: Office availability of nitrous oxide analgesia RESULTS: Following the introduction of nitrous oxide, the proportion of endometrial sampling procedures (hysteroscopies with and without morcellation, dilation and curettage and endometrial biopsies) performed in the operating room decreased significantly from 28% to 16% (p <0.001), with a corresponding increase in office-based procedures from 72% to 84% (p <0.001). After nitrous oxide withdrawal, operating room-based procedures increased to 25% (p <0.01), and office-based procedures decreased to 76% (p <.01). Similarly, the proportion of hysteroscopies (with and without morcellation) done in the operating room decreased from 89% to 69% during nitrous oxide implementation (p <0.001), with a corresponding increase in office-based hysteroscopies from 11% to 31% (p <0.001). Operating room-based endometrial biopsies and D&Cs decreased from 3.6% to 2.3% (p =0.17) during nitrous oxide implementation. Office-based endometrial biopsies and D&Cs correspondingly rose from 96.4% to 97.7% (p=0.17) during nitrous oxide implementation. In addition, the proportion of insufficient endometrial sampling (defined as inadequate tissue for pathologic diagnosis) was similar between the pre-implementation and nitrous oxide implementation periods (10.8% vs 9.3%, p = 0.37).

In an outpatient gynecology setting, the availability of nitrous oxide analgesia was associated with a higher proportion of endometrial sampling procedures performed in the office rather than the operating room. This association was driven predominantly by a shift in hysteroscopic procedures.