Encrustation and stone formation: complication of indwelling ureteral stents.

Severe encrustation and stone formation on indwelling ureteral stents in 2 patients with a lithogenic history are reported. In both cases this complication occurred in the presence of sterile urine and treatment required pyelolithotomy in one and renal pelvic irrigation with urologic G solution in the other. Analyses of these stones revealed struvite and apatite, respectively. Dissolution of encrustations and stones via renal pelvic irrigation is suggested as a viable alternative to surgical intervention for this problem. A review of the literature shows a correlation between chronic stone formers and stent encrustation, rather than from bacteriuria alone. Long-term antibiotic suppression, more frequent followup with abdominal roentgenograms, and shorter periods of internal stenting are suggested for patients with a lithogenic history.