A computerised vector manometry study of the so-called ectopic anus.

There are several totally different definitions of the so-called ectopic anus. To determine whether computerized eight-channel manometry helps to define the entity of the ectopic anus, ten patients (nine females) were operated upon for an ectopic anus by the anal transposition technique (perineal pull-through procedure). Besides the software-supported manometric data, the qualitative imaging analysis was of interest. We calculated the factor by which the pressure of the three ventrally-located segments was lower than the mean segmental pressure at this part of the anal canal. The results were compared to standard age-related values established in a former study in 100 children. Besides pre- and postoperative manometry, barium roentgenograms were obtained. The anal-canal length at rest in the ectopic anus was significantly (P < 0.0001) longer. The segmental asymmetry index in the lower anal canal (LAC) was increased, but not significantly. The pressure in the ventral segments of the LAC was significantly (P < 0.0001) decreased and was less than one-half of the mean segmental pressure in this zone. We found a significant correlation between the degree of anterior displacement and the factor by which the ventrally-located pressure values were decreased. Postoperatively, this factor increased significantly. From a functional point of view, the definition of the ectopic anus includes a deficient high-pressure zone ventrally in the LAC. The LAC seems to run out or nearly out of the ventral sphincteric issue to end ectopically on the perineal surface.