Effects of the menstrual cycle on injection pain due to rocuronium

Study ObjectiveTo investigate the effect of the menstrual cycle on rocuronium injection pain.DesignProspective, randomized, double-blinded study.SettingAcademic medical center.Patients80 ASA physical status 1 and 2 women scheduled for elective surgery with general anesthesia.MeasurementsPatients were divided into two groups according to their time in the menstrual cycle. Forty patients at days 8 to 12 of the menstrual cycle were considered to be at the follicular phase (Group F), and 40 patients at days 20 to 24 of the menstrual cycle were considered to be at the luteal phase (Group L).Withdrawal movements were recorded.Main ResultsOverall frequency of withdrawal movements was significantly higher in Group L than Group F (P < 0.001). The mean withdrawal movement score was 1.77 ± 0.76 in Group L and 0.52 ± 0.67 in Group F.ConclusionMenstrual cycle phases affect the severity of rocuronium injection pain. Women exhibit greater pain sensitivity from rocuronium injection in the luteal phase than the follicular phase.