Assessment of depth of invasion in rectal cancer by endosonography.

Pre-operative staging of rectal cancer could be significantly improved by the imaging method of endorectal ultrasound. Using high-frequency transducers a complex rectal wall pattern was demonstrated. Depending on in vitro or in vivo examinations and on US probes of different frequency the current interpretation is not uniform. Agreement exists on the interpretation of the muscularis propria which is of clinical importance. Objective and precise criteria for lymph node differentiation have yet to be worked out.