Lei Zhao, Hua Du, Benhong Li, Shuang Wu, Nan Lin and Liying Cui
Objective: To explore the impact of physiological factors, such as age, gender, and childbirth experience, on
external anal sphincter electromyography.
Methods: A total of 62 healthy volunteers (37 women and 25 men) participated in the study.The female subjects
were divided into three groups according to various childbirth experiences: the nulliparous group, the caesarean
group, and the vaginal delivery group. Motor unit potentials were obtained from the bilateral external anal sphincter
of each subject using multi-MUP analysis. The mean values of each parameter (including duration, amplitude, area,
mean number of turns, mean number of phases, and satellite rate) were calculated for each subject. The impact of
age, gender, and childbirth experience on the parameters of the anal sphincter electromyography were analyzed
statistically.
Results: The mean durations were longer and the satellite rates were higher in the vaginal delivery group than in
the nulliparous or caesarean groups. There were no significant differences in any of the electromyography
parameters between the nulliparous and caesarean groups. None of the electromyography parameters
changedsignificantlywith increases in vaginal delivery times. A multiple linear regression analysis of each
electromyography parameter for age, gender, and vaginal delivery experience indicated that gender and vaginal
delivery experience influenced the parameter of duration; vaginal delivery experience also influenced the parameter
of satellite rate; and age did not significantly affect any of the parameters except the number of phases.
Conclusion: Age, gender, and vaginal delivery experience impact differently on the various anal sphincter
electromyography parameters. These variables should be taken into consideration when interpreting
electromyography results in clinical work.
