[Ultrasound diagnosis of rare retrorectal tumors].

The diagnosis of perirectal masses can be accomplished by computer tomography and magnet resonance imaging if the rectum is contrasted. The accuracy of these methods is > 90 %. But often the assessment of the exact borders with respect to the rectum wall and to the genitalia is difficult. Therefore transrectal 3D-ultrasound is of major importance in the preoperative staging and postoperative follow-up of rectum cancer and allows the diagnosis of pararectal findings using the ultrasound-guided, transrectal aspiration. By ultrasound-guided aspiration biopsy we detected five cases of pararectal and especially presacral diseases including one case of endometriosis. The diagnostic algorithm is described.