RESUMO
BACKGROUND AND PURPOSE: Urologic resectoscope loops often are manipulated to reposition the angle. The effects of these maneuvers on the efficiency and functionality of the loop have never been tested. Our goal was to evaluate the changes in tensile strength, conductivity, and dispersion of cautery effect resulting from such manipulation. MATERIALS AND METHODS: Resectoscope loops manufactured by Karl Storz, Olympus, Boston Scientific, and ACMI were tested for tensile strength and unevenness of cautery effect before and after one manipulation from an angel of 15 degrees posterior to 15 degrees anterior deviation. RESULTS: Prior to manipulation, the loops demonstrated a tensile strength of approximately 40 lb to failure. After one manipulation, the tensile strength was reduced by 90.1% (P < 0.001), with 46.7% of the loops failing to meet minimum industry standards. Manipulation of the loops increased the resistance to current flow within the wire. Microscopic evaluation showed longitudinal fracture lines at the manipulated sites. CONCLUSION: Physician-manipulated resectoscope loop angles have a dramatic effect on the strength of the loop as well as the dispersion of energy. A bend of 30 degrees results in 46.7% of the loops failing to meet minimum tensile-strength standards and alters the effectiveness and dispersion of electrical current. Infrared photography confirms the defect to be generated at the point of manipulation, thereby reducing the anticipated capabilities at a constant setting of the loop energizer. Ultimately, the quality of surgical resection suffers from even one manipulation of a resectoscope loop.