endorectal ultrasound (en-doh-REK-tul UL-truh-sownd)
A procedure in which a probe that sends out high-energy sound waves is inserted into the rectum. The sound waves are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissue called a sonogram. Endorectal ultrasound is used to look for abnormalities in the rectum and nearby structures, including the prostate. Also called ERUS, transrectal ultrasound, and TRUS.