Effect of partial ureteral obstruction location and severity on urinary system stone disease formation

INTRODUCTION AND AIM: We aimed to observe the effect of location and severity of partial ureteral obstruction, based on the ureteropelvic and ureterovesical junction strictures, on stone formation. MATERIAL AND METHOD: Forty 8-week-old male rats were included in the study and the rats were divided into 5 groups. We determined the groups as the control group, mild/severe obstruction groups at the proximal and distal ureter. Partial ureteral obstruction was created appropriate to the obstruction groups by surgical procedure. After 5 days of intraperitoneal glyoxylate injection, biochemical samples were taken from the rats and bilateral nephrectomy was performed. Urine and blood samples were analyzed and the kidney tissues were examined histopathologically. RESULTS: A statistical differences were found between the groups in terms of urine citrate, pH value, oxalate/creatinine, citrate/creatinine, calcium/creatinine ratios (p<0,05). The mean value of the citrate/creatinine ratio was found to be 21,13±0,44 in the control group; 17,31±3,82 in the groups with distal obstruction; and 15,48±1,87 in the groups with proximal obstruction. When the obstruction degrees were compared with the control group, it was observed that urine citrate, pH value, citrate/creatinine and calcium/creatinine ratios were lower and oxalate/creatinine ratio was higher in severe obstruction than in mild obstruction. It was observed that the crystal score increased as the pelvic diameter decreased and the parenchymal thickness increased in the obstructed kidney (p<0,00; p<0,00). A difference was detected between oxalate (61,54±53,24; 77,92±49,73) and oxalate/creatinine ratio (72,38±65,33; 98,96±58,96) in the absence and presence of CaOx crystals (p <0,025; p<0,019). CONCLUSION: Our study is the first to use partial ureteral obstruction and urolithiasis model together. As a result of our study, it was observed that the level and degree of ureteral obstruction does not directly cause kidney stones, and urinary stasis changes parameters such as citrate, pH, citrate/creatinine in urine. Since these parameters are factors that make stone formation easy, these patients are indirectly at risk for stone formation. In addition, our study also showed that fewer CaOx crystals were formed in the obstructed kidney than in the opposite kidney. Stone formation in urinary system obstruction has been shown to be a complex process. However, we think that possible complications of surgical treatment can be avoided with metabolic evaluation and prophylactic treatment in patients with ureteral obstruction when they are stone-free or after surgical removal of the stone.