Incidence and risk factors for epidural morphine induced pruritus in parturients receiving cesarean section: A prospective multicenter observational study.

This study is designed to clarify the incidence of epidural morphine induced pruritus (EMIP) in Chinese Han and Tibetan parturients after cesarean section (CS) and to identify the correlated risk factors. This is a prospective multicenter observational study. Follow-up evaluations were performed at 3hours, 6hours, 12hours, 24hours, and 48hours after morphine administration. The primary outcome was EMIP incidence. Other details were also recorded for risk factor screening. Totally 284 parturients receiving CS were enrolled and 247 completed the study. The overall incidence of EMIP was 18.6% (46 in 247). The onset of pruritus was 5.6 +/- 4.8 hours (mean +/- SD) after morphine administration and the duration of pruritus was 14.0 +/- 8.8 hours. Logistic regression models was built with 5 variables, history of allergy, serotonin receptor antagonist administration, I.V. fentanyl administration, epidural morphine volume and VAS pain score. Results of showed that 2 of the variables, history of allergy (P<.001) and serotonin receptor antagonist (P<.05), were significantly correlated with incidence of EMIP. In conclusion, EMIP incidence in our study was 18.6%. Positive medical history of allergy and not using serotonin receptor antagonist were potential risk factors of EMIP development.