The
rectal ampulla (or
ampulla recti) is the dilated section of the
rectum where
feces are stored until they are eliminated via the
anal canal. The caliber of the rectum at its commencement is similar to that of the
sigmoid colon, but near its termination it dilates, forming the ampulla. An ampulla is a cavity, or the dilated end of a duct, shaped like a Roman
ampulla.