There has been considerable technical development in the radiology of anore
ctal disorders, involving fluoroscopic and dynamic MR imaging studies and e
ndosonography assessment of the anal sphincters. Endoanal ultrasound is an
ideal screening examination for incontinence to show internal sphincter deg
eneration and tears of the internal or external sphincters. The diagnosis o
f external sphincter atrophy on ultrasound is not yet resolved, and this re
mains an important indication for endoanal MR imaging.