Endoanal Ultrasound is a technique that provides imaging of the anal sphincter complex (The muscles around the anus which control passage of stool) and the surrounding tissues. This technique involves passage of ultrasound transducer or probe into the anal canal to directly assess the structures. It is mainly used to assess abscess (collection of pus), fistula or cancers around the anal canal/rectum. It is relative pain free and takes about 10 minutes to do.