A model of suture-induced urolithiasis with urographic control in the bladder of the rat

The characteristics of a model of urolithiasis in the bladder of male Wista r rats were evaluated, Two techniques were compared: one knot of suture mat erial through the bladder wall, or 15-throw knots inside the bladder. Rats were randomly assigned to one of six groups, according to the technique and suture material used (polyester, silk, or chromic catgut). An excretory ur ogram was performed at days 30, 60, and 90. At the moment of positive radio graphic diagnosis, animals were sacrificed and stones were obtained. All ra ts were sacrificed at day 90 regardless of the x-ray results. Variables eva luated were average days to a positive urogram, average weight of all uroli ths, and percentage of animals developing urolithiasis throughout the study . There were no statistical differences between groups for the average weig ht of stones, which ranged from 0.008 to 1.502 g for individual cases. All three materials were more lithogenic with the 15-throw knot inside techniqu e, No significant differences were detected for lithogenesis criteria betwe en suture materials. X-ray dispersion spectroscopy evidenced calcium phosph ate composition of two stones from chromic catgut, and magnesium phosphate composition of two stones from chromic catgut, two from silk, and two from polyester. Neo-epithelization over the suture was confirmed microscopically in bladders with the one-throw technique. We conclude that (1) this is an effective model of urolithiasis, with predictability in time, composition, and amount of stone formation; (2) the presence of more suture material ins ide the bladder is more lithogenic; and (3) excretory urograms are highly s ensitive and specific for the noninvasive diagnosis of bladder urolithiasis .