Congenital deformities of the anus and the rectum.

One of the regular methods of progression in medicine is by the analysis of large vaguely assorted groups of cases into smaller and exactly defined categories. The process consists in a mixture of observation, abstract reasoning and experiment. As instances of this the work of Hamilton Russell (1922) may be quoted, when by a combination of observation and abstract reasoning he established the existence of inguinal hernias due to a congenital malformation, and distinguished them from those due to purely mechanical causes, which had been classed with them. Then there is the work of Swenson and Bill (1948), which has split up the vague group classed under the unhappy name of megacolon into two classes, one being that of Hirschsprung's disease, a congenital deformity consisting in the absence of ganglion cells in the bowel, and the other a functional failure to empty a normal bowel which can be called 'colonic inertia'. In the same way the splitting up of the group of 'undescended testicles' into 80% of normal variations in development, the retractile class, and 20% of congenital deformities, has made it possible to give definite prognoses and indications for treatment where both were lacking before. It is the purpose of this lecture to suggest that a similar process may with advantage be applied to the heterogenous group known by the name of imperforate anus. We have found that two conceptions have helped greatly in classification and, far more important, in treatment. These conceptions are those of the ectopic anus, a normal sphincter mechanism which has become displaced as a testicle in its descent may take the wrong line; and the covered anus, in which a normal mechanism has been buried by a process not usually recognized, that of excessive fusion of embryological structures. This failure of development, whose existence was suggested to me by Douglas Stephens, is, of course, the reverse of the