Ectopic anus in eight patients was assessed functionally by means of electromanometric and electromyographic techniques. These methods safely and adequately distinguish a functional ectopic anus from a fistula. In all cases presented, the internal anal sphincter was found to surround the ectopic anal canal. The normal connections between the rectum and internal sphincter and the rectum and external sphincter were conserved after anal transplantation in two patients. The path of the rectoanal reflex seems to be localized in the anorectal wall.
Kerremans RPJ, Penninckx FMA, Beckers JPV. Functional Evaluation of Ectopic Anus and Its Surgical Consequences. Am J Dis Child. 1974;128(6):811-814. doi:10.1001/archpedi.1974.02110310059010