A medical apparatus and method useful for resecting tissue from the gastrointestinal tract are disclosed. The apparatus can include an RF tissue cutting device disposed inward of a side opening in the device. A tissue stop can be used to control the depth of tissue resected, and the tissue stop can include holes for communicating vacuum for drawing tissue into the side opening. The tissue stop can be electrically grounded with respect to the RF tissue cutting device, and the tissue stop can provide one pole of an RF electrical circuit.