An instrument for use with an endoscope may include an elongate section configured to move exterior to the endoscope. The elongate section may include a distal end and a proximal end. The instrument may also include an end effector attached to the distal end of the elongate section, and an actuation device attached to the proximal end of the elongate section. The actuation device may be configured to operate the end effector. The instrument may also include a guiding member coupled to the elongate section. The guiding member may be configured to be coupled to an external surface of the endoscope to permit the guiding member to move longitudinally relative to the endoscope. The guiding member may be coupled to the elongate section such that the end effector may extend past a distal end of the endoscope and move in a transverse direction independent of the movement of the distal end of the endoscope.