The electromyographic examination to evaluate the external sphincter muscle in anorectal malformations.

Preoperative electromyographic examination is very useful in locating the external sphincter muscles and determining their degree of development. Electromyographic examinations showed the relatively abundant distribution of the external sphincter muscles in the perineum even in high-type anomalies. The results obtained by these examinations lead to the conclusion that preserving both the puborectal and external sphincter muscles should be the main consideration in surgery for anorectal malformations.