150 toward and into the flexible tube 132 to facilitate one hand control of the reciprocal motion of the control slide 122 finger rings 124 126 may be attached to the central portion 123 of the control slide 122 and a thumb ring 120 may be attached to the proximal portion 118 of the body 112 it will be understood by those having ordinary skill in the art that other mechanisms could be used in the snare control module 110 without departing from the scope and spirit of the present invention such mechanisms may include for example slide actuators without finger rings and actuators configured for use in electro cautery the surgical instrument 100 also includes a tether 160 that can be used to assist in maneuvering the snare loop 150 the tether 150 is attached to the flexible tube 132 and the snare loop 150 so that extension of the snare loop 150 a predetermined distance from the distal tube end 133 causes the snare loop 150 to deform from a substantially planar condition as shown in fig2 to a curved three dimensional condition as shown in fig4 as will be discussed deforming the snare loop 150 in this manner serves to facilitate the positioning of the snare loop 150 for capturing body tissue such as polyps the tether 160 of the surgical instrument 100 has a distal end 164 that is attached to the loop member 152 and a proximal end 162 that is attached to the flexible tube 132 in the illustrated embodiment the proximal tether end 162 is attached to the flexible tube 132 at an attachment point 163 near the distal tube end 133 the proximal tether end 162 may be attached to the flexible.