The identification and management of anorectal anomalies. The factors ensuring continence.
In this paper, anorectal anomalies are classified according to a scheme devised at an international conference of 200 paediatric surgeons in 1970 in Melbourne, Australia. The classification is based upon the pathological anatomy of each type in relation to the sphincters available for reconstruction. A diagnostic plan of identification of each type is presented; this is based upon accurate observations of the external clinical appearance, the site and type of orifice, and the presence or absence of meconium in the urine. Extension of the detailed diagnosis is obtained with radiological studies - gas shadows in the inverted position and radio-opaque dye studies in the various orifices. The errors of interpretation of these investigations are discussed. The objective of surgery is a continent anus. The achievement of continence depends on several factors: (i) accurate pre-operative assessment of the anomaly and the available sphincters, with their nerve supply (ii) an operative technique which positively identifies the sphincters, and preserves them intact and undamaged (iii) supervision of the post-operative management, including gentle dilatation of the puborectalis muscle, avoidance of constipation, and advice on training. The various operative techniques for both high and low anomalies are described.