Electromyographic Examination of External Anal Sphincter in Anorectal Malformation

External anal sphincter electromyography was performed with surface electrode in 32 preoperative patients with anorectal malformations.The amplitude and the frequency during rest and stimulating period in these patients were compared with those in control group.Two values of electromyographic activities were much lower than normal(P＜0.05)in high rectal malformation and one value lower in intermediate(P＜0.05).There are no significant difference between control and low type.Examination at different places around the anal dimple demonstrated marked difference in abnormal distribution.The results show that the higher the rectal pouch,the poorer the anal sphincter,and the more abnormal the muscles.