[Endosonographic determination of the volume of anal sphincter muscles as a parameter for continence outcome in childhood].

The volumes of the external and internal anal-sphincter muscles, determined by three-dimensional (3d) endosonography, are linear to each other and to the body-height and body-surface ratios in normal children. In patients with an operation of the sphincter muscles, the reduced volume of the external sphincter system permits a differentiation of incontinent children; the volume of the internal sphincter muscles, however, doesn't give a significant difference nor does the muscle-thickness. An acceptable estimation of the sphincter muscles volume can be made with conventional endosonography by planimetry of the muscle tissue in four representative axial cut-planes and by measuring of the sphincter-length.