Intraanal ultrasound: a new aid in the diagnosis of pelvic processes and their relation to the sphincter complex.

Intraanal ultrasound provides a very accurate structural analysis of the continence organ. In addition it proved to give excellent pictures of solid or fluid intrapelvic, particularly retrorectal, structures. It is superior to computed tomography and magnetic resonance imaging (requiring anesthesia), because the scanner is very close to the structures in question. This allows high scanner frequencies with resolutions of 0.9 mm and better. It is a quick method, avoiding radiation, and can be safely repeated as often as necessary.