The advertised total and core diameters of laser fibers for urological surgery do not correspond with the actual diameters, according to a new study. Furthermore, there are serious differences between manufacturers of fibers with supposedly equal diameters. Urologists need to know the exact technical specifications of the material they use, said Dr. Peter Kronenberg of Hospital Fernando Fonseca in Amadora, Portugal, who conducted the study with professor Olivier Traxer of Hôpital Tenon in Paris. “If the information conveyed to them, whether written on a product label or transmitted by an industry representative, is incorrect, their judgments and the decisions they make based on this knowledge may have surgical repercussions,” Kronenberg said. They evaluated 14 different laser fibers from six brands with advertised diameters of 200, 270, 272, 273, 365 and 400 µm, taking multiple measurements of both the total diameter (including fiber coating) and the fiber core diameter and comparing them to their respective advertised diameters. The total and the core diameters measured were both significantly different from the advertised diameter in all fibers (p The study won the Clinical Research Award at the second meeting of the EAU Section of Urolithiasis (EULIS) in Copenhagen, Denmark. The findings warrant attention from the urological community – larger-than-advertised laser fibers influence irrigation flow, visibility, scope deflection and stone retropulsion – and the manufacturers of these fibers should consider the implications as well.