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Purpose: To compare the effectiveness, potential advantages and complications of classical open pyeloplasty with retroperitoneoscopic pyeloplasty in children., Materials and Methods: Two patient cohorts with confirmed ureteropelvic junction obstruction (UPJO) undergoing open or retroperitoneoscopic pyeloplasty over a 7-year period were analysed comparatively., Results: Operative time was significantly longer in the retroperitoneoscopic group (mean 155 min) compared to the open pyeloplasty group (mean 98 min, P<0.05). Mean hospital stay was shorter in the retroperitoneoscopic group (mean 4.1 days, compared to 5.1 days, open). Complication rates were similar (open, 27% vs retroperitoneoscopic, 29%). These included anastomotic urinary leakage, stenosis and infection. Anastomotic leakage was more common in the retroperitoneoscopic group. There was a 6.6% conversion rate in the retroperitoneoscopic group. Success, defined as improved ultrasonic or renographic parameters, with resolution of symptoms where discernable, was noted in 96% of the open group and 97% of the retroperitoneoscopic group with a mean follow up of 38 and 25 months, respectively., Conclusions: Retroperitoneoscopic pyeloplasty is as safe and effective as open pyeloplasty. This technique is now our procedure of choice for children>4 months old. The advantages are more obvious in children over 4 years than in infants. This technique remains difficult to perform and teach.

Purpose: We evaluated the long-term consequences of complete fetal UUO on renal hemodynamics and anatomy., Materials and Methods: A total of 26 fetal lambs underwent surgical UUO at 90 days of gestation and 14 twin matched animals served as controls. Synchronous bilateral ARBF was measured using mean transit time technology. Standard anatomical analysis, including evaluation of RPV, was performed in the kidneys. Measurements were done 10, 20 and 40 days following UUO in groups 1 to 3, respectively and in 1-month-old lambs in group 4., Results: All obstructed kidneys underwent typical hydronephrotic transformations with a progressive decrease in parenchymal volume compared to that of contralateral and control kidneys. ARBF in obstructed kidneys was significantly decreased compared to their contralateral counterparts in all groups (p <0.01). Comparing ARBF to RPV showed that the decrease in ARBF was proportional to the loss of parenchymal volume in fetal obstructed kidneys but it remained significant in lambs (p <0.05)., Conclusions: Complete UUO alters ARBF, while vascularization of the remaining renal parenchyma is maintained in fetuses. Profound impairment of the renal arterial supply observed in lambs may be due to physiological changes linked to birth.

Purpose: We analyzed the dynamics of the renal tissue response to experimental fetal urinary flow impairment concerning renal morphology, extracellular matrix composition, regulators of connective tissue degradation and PAX2 protein expression., Materials and Methods: A total of 26 fetal lambs underwent surgical unilateral ureteral obstruction at 90 days of gestation and 14 twin matched animals served as controls. Kidneys were harvested 10, 20 and 40 days after the prior procedure in groups 1 to 3, respectively and in 1-month-old lambs (group 4). Morphological analysis was done using light microscopy. Picrosirius red staining was used to evaluate the area occupied by extracellular matrix components. Collagen I, III and IV, alpha-smooth muscle actin, MMP-1, 2 and 9, TIMP-1 and 2 and PAX2 protein were assessed using immunochemistry., Results: All obstructed kidneys were hydronephrotic without dysplasia. Hypoplasia resulting from a decreased NGG was observed. The inflammatory response to obstruction was poor in fetal obstructed kidneys. From 10 days after obstruction interstitial fibrosis was noted and confirmed by an increase in picrosirius red staining. In obstructed kidneys immunochemistry showed an increase in collagen deposition beginning from the papillae and extending through the whole parenchyma. Aberrant interstitial collagen IV deposition was observed. The increase in alpha-smooth muscle actin staining was mainly localized in the blastema and interstitial cells in obstructed kidneys. MMP and TIMP immunostaining was mainly present in tubules throughout the whole nephrogenic period and persisted in mature kidneys. Beginning from 20 days after obstruction a progressive increase in MMP and TIMP expression was noted. This was associated with ectopic expression in the medullary tubules. PAX2 protein was highly expressed in the nephrogenic zone, decreasing progressively to being markedly decreased in control lamb kidneys. No difference was found in PAX2 expression during the fetal period when comparing unobstructed and obstructed kidneys, it but remained strongly expressed in the dilated collecting ducts of obstructed lambs., Conclusions: Complete unilateral ureteral obstruction performed in fetal lambs at 90 days of gestation led to pure hydronephrotic transformation, hypoplasia and a marked increase in connective tissue deposition. Inflammatory infiltrates and PAX2 dysregulation were not seen as having a decisive role in these modifications.