Introduction: The aim of this study is to perform a literature review of stiff guidewires used in urology and to investigate if there is an official definition for stiffness (shaft rigidity) of wires. Materials and Methods: A literature search was performed for all English language articles in MEDLINE and Scopus databases, Google Scholar, and the official websites of international companies. Guidewires from different companies were included. Results: We analyzed 14 different stiff guidewires from the companies, Boston Scientific, Coloplast, Cook Medical, Olympus, Terumo, Rocamed, and Bard Urological, according to their characteristics. We found no concrete data regarding their stiffness on the official websites. In addition, there were a few published studies about the Amplatz Super Stiff guidewire (Boston Scientific), ZIPwire™ Stiff Nitinol Hydrophilic guidewire (Boston Scientific), HiWire Stiff Nitinol Core Wire Guide (Cook Medical), Amplatz Fixed Core Wire Guide (Cook Medical), and NiCore™ Nitinol Guidewire-Stiff (Bard Urological), whereas there were no available data for the majority of stiff guidewires. Conclusions: Stiff guidewires are listed in catalogs of companies without any information regarding their classification. They are only divided into stiff and standard versions without knowing the differences between them. The companies and their manufacturers should adopt a common method to calculate and define the stiffness of each guidewire.
Keywords: definition of stiffness; endourology; guidewire; stiff guidewire; stiffness; ureteroscopy.