an apparatus and method are disclosed for measuring the desired length of a prosthetic device which is to be implanted in a body cavity of a patient . the apparatus generally includes a helically coiled stent formed of a resiliently - deformable material , a plunger which is connected to the proximal end of the stent , a sheath which slides over the plunger and stent when the plunger and sheath are used to insert and removably deploy the stent into the body cavity , and a scale for measuring an indication of the length of the stent once removably deployed in the body cavity . proximal movement of the sheath to partially deploy the stent causes a length to be indicated on the scale . according to the method of the invention , the helically coiled stent of the apparatus is placed and partially deployed within the body cavity by use of the plunger and sheath of the apparatus . once the stent bridges the body cavity , the scale of the apparatus is used to determine the length of the deployed stent . the apparatus is then removed from the body cavity , and a stent similar to the stent of the apparatus is cut to the length indicated on the scale . in a second embodiment of the apparatus and method , the stent of the measuring apparatus is substantially non - porous to allow occlusion of side vessels extending from the body cavity . the patient is then monitored for any ill effects resulting from the occlusion .