Equipment is disclosed for shielding a catheter such as a balloon-tipped vascular catheter from contamination during testing and insertion and for shielding a substantial reserve catheter section for use if catheter re-positioning is necessary. As shown, the structure includes two interconnecting envelopes which physically isolate the catheter. One envelope is designed to shield the distal end portion of the catheter during testing for luman patency and balloon inflation. The other envelope is extendible to cover the entire length of catheter intended for insertion into the patent upon completion of required tests. The second envelope thereafter provides a means for advancement or re-positioning of the catheter or withdrawal of the same without physical contact by the hands or exposure to airborne contaminants.