Abstract
On reconstructing infrapelvic structure in patients with imperforate anus, it is essential to pull the anorectum through correctly. To apprehend the ideal pull-through route stereoscopically, three-dimensional images of the pelvic structure were obtained after processing MR images from 10 patients with the anomaly and 7 controls. In controls, the infrapelvic muscle structure, which is composed of bilateral superficial perineal muscles, levator muscle complex and sphincter muscle complex, was demonstrated to converge at the center. The rectum was shown stereoscopically to descend through this central portion of the muscle, making an anoreclal angle to reach the anal orifice. In those with a low-type anomaly, the rectum was shown to descend in front of the levator muscle complex and the fistula ran through the anterior portion of the sphincter complex without making an anorectal angle. The purpose of the anoplasty for those patients was considered to make a correct anorectal angle. In those with a high-type anomaly, three-dimensional position of the rectal pouch was visualized within the normally-positioned muscle complex but the sphincter muscle was thinner than control patients. For the ideal anoplasty in those patients, the rectum should be conducted into the center of the muscle complex and pulled through in the midst of the thin sphincter mass after making an anorectal angle. Anoplasty procedures should be reevaluated whether they are good for making an ideal pull-through route by three-dimensional images of the infrapelvic organs.
