Nitrous Oxide for Pain Management During In-Office Hysteroscopic Sterilization: A Randomized Controlled Trial [21O]

    loading  Checking for direct PDF access through Ovid



To evaluate whether inhaled nitrous oxide with oxygen (N2O/O2) is superior to oral sedation for pain management during in-office hysteroscopic sterilization.


This double blinded randomized controlled trial enrolled women undergoing in-office hysteroscopic sterilization. The intervention group received N2O/O2 titrated to a maximum 70%:30% mixture and placebo pills pre procedure. The control group received inhaled O2 during the procedure and 5/325 mg hydrocodone/acetaminophen and 1 mg lorazepam pre procedure. The primary outcome was maximum procedural pain on a 100 mm Visual Analogue Scale (VAS) assessed 3–5 minutes post procedure. A sample size of 30 women per treatment arm was required to detect a clinically significant pain difference of 20 mm on the VAS.


72 women, 36 per study arm, were randomized to account for unsuccessful bilateral coil placement and drop out after randomization. Two women in the study group and 6 in the control group were excluded due to unsuccessful bilateral coil placement. Mean age of participants was 34.1±5.7 years and mean BMI was 30.1±6.6 kg/m2. Mean maximum procedural pain scores were 22.8±27.6 mm and 54.5±32.7 mm for study and control groups, respectively (P<.001). Most study participants (97%) stated NOS should be offered for gynecologic office procedures and 86% would pay for NOS if it were not a covered benefit.


NOS decreased pain with in-office hysteroscopic sterilization compared to oral sedation. Given its safety and favorable side effect profile, NOS should be considered for routine availability for in-office hysteroscopic sterilization.

Related Topics

    loading  Loading Related Articles