Objective To report the results of a comparative study of in vitro encrustation of five different types of JJ stents in human urine. Materials and methods Samples of five JJ stents (polyurethane, silicone, Percuflex, C-Flex and hydrogel-coated C-Flex) were immersed for 24 h at 37 degrees C in fresh human urine supplemented with urease, and the surface photographed and dried. The crystals formed on the stents were dissolved in hydrochloric acid and the calcium and magnesium concentrations determined. Results Large crystals were deposited on the surface of the hydrogel-coated C-Flex stent and significantly higher levels of calcium and magnesium salts were obtained after acidic dissolution, There were no differences in crystal deposition among the remaining stents. Conclusion Hydrogel-coated stents have an higher risk of becoming encrusted in vitro than do uncoated stents made of the same substrate polymer or made of different materials. These results emphasize the need for the regular fellow-up of patients with hydrophilic stents in place.
