An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter.

The pulsed dye laser was used to fragment ureteric calculi in 10 pig ureters, compared to electrohydraulic disintegration in six pig ureters. The stones were impacted in the proximal ureter and approached by rigid ureteroscopy. Four ureters did not have stones impacted but had ureteroscopes passed. The stones were fragmented and the particles left to pass spontaneously. The degree of inflammatory reaction was graded at the site of fragmentation as well as in the middle and lower ureter. The degree of inflammation seen at the site of fragmentation was significantly less in the laser group than in the electrohydraulic group (p = 0.0027). It was noted that the degree of inflammation seen in the lower ureter was significantly greater than that seen at the site of fragmentation (p = 0.01), and that this grade of inflammation correlated well with the size of ureteroscope used (p = 0.0026). Further, the degree of dilatation of the ureter and pelvicalyceal system was significantly greater when the larger calibre ureteroscope had been used (p = 0.0056) ranging up to hydronephrosis with flattening of the papillae. If there is any parallel which can be drawn between the pig ureter and the human ureter then it suggests that ureteroscopy is more significant than the modality of fragmentation used. The contribution of the laser may therefore be more by the miniaturization of instrumentation which will be made possible than by any advantage it may have as a fragmenter.