Transrectal ultrasonographic examination of the anal sphincter.

Transrectal Ultrasonography (TRU) provides an excellent imaging of the rectal wall, the perirectal structures (1) and especially of the anal sphincter (2,3). We used a rigid endorectal probe with a linear and a radial ultrasonic window, and with a frequency of 5 MHz (model IUV 5060; Toshiba, Japan). The linear scanning provided a better imaging of the anal sphincter and was preferred to the radial scanning, especially when measuring the sphincter dimensions.