At this point in time, endopyelotomy is first-line therapy for both primary and secondary adult ureteropelvic junction obstruction (UPJO) in many medical centers. However, the potential, albeit small, for significant bleeding with any endoincision of the UPJ has sparked interest in the simple, less morbid technique of endoballoon rupture. To date, no comparative data are available on the effectiveness of these two techniques. Thirty female minipigs were randomized to cutting balloon (Acucise) endopyelotomy (AEP) (N = 13), endoballoon rupture (EBR) (N = 13), or a control arm (N = 4). Following baseline retrograde pyelogram (RPG) and diuretic renogram (DRG), a secondary proximal ureteral stricture was created by laparoscopic ligation of the UPJ. After 8 weeks, AEP or EBR was performed in each of the study pigs. In 16 pigs (8 AEP, 8 EBR), a 7F 22-cm ureteral stent was placed (chronic arm). After 6 weeks, the stent was removed, and a second RPG and DRG were performed. Three months post-treatment, after RPG and DRG, the renal units were harvested, and histologic sections of the affected UPJ, contralateral normal ureter, and ipsilateral kidney were examined. Ten pigs (5 AEP, 5 EBR) underwent harvest immediately after treatment (acute arm). The four control animals remained untreated. At 8 weeks, all minipigs had obstructive findings on RPG and DRG. All UPJs could be treated but one, which had an impassable stricture; there were no perioperative complications. In the acute arm, all UPJs were patent. All five AEP ureters had evidence of an uneven cut and cautery effect. Of the EBR ureters, two had smooth tears and three had ragged tears, and none had evidence of cautery effect. In the chronic arm, 3 months after either AEP or EBR, all minipigs had a patent UPJ, yet only 5 of 16 had an improved t( 1/4 ) by DRG. Histologic sections of the affected UPJs from 20 minipigs in the chronic arm (8 AEP, 8 EBR, 4 controls) were indistinguishable among the three groups; each revealed significant periureteral fibrosis and chronic inflammation with a mainly unremarkable muscular layer. However, histologic sections of 25 treated kidneys, including both acute and chronic animals (13 AEP, 12 EBR), revealed end-stage renal disease (N = 10), chronic inflammatory changes (N = 7), or normal tissue (N = 8). Again, there was no trend favoring either AEP and EBR. In summary, in this laboratory study, we could detect no difference in outcome between an incisional endopyelotomy and an endoballoon rupture for treating secondary UPJO.
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