The maximum anteroposterior diameter of renal pelvis changes by hydration in cases of ureteropelvic junction obstruction

Objective: The aim of this study is to investigate the degree of variation of hydronephrosis by hydration in patients with ureteropelvic junction obstruction (UPJO). Material and Methods: Patients with antenatally diagnosed UPJO who admitted in a three months period were evaluated in terms of variation in sonographic findings for hydronephrosis. Serial renal ultrasounds were carried out before and after hydration considering parameters for hydronephrosis. Parameters evaluated on each ultrasound included degree of hydronephrosis, maximum anteroposterior diameter of the renal pelvis (mAPD) and anteroposterior pelvic diameter at hilum (hAPD), renal parenchymal thickness, dimensions of both kidneys, grade of hydronephrosis and the volume of the bladder. Results: Eleven children with unilateral hydronephrosis due to UPJO were evaluated. There were 10 males and 1 female at a mean age of 10.3 (3-30) months. The mean value of mAPD before hydration was 19.3±4.3 and increased to 21.3±4.6 mm (9.6% increase) after hydration showing a statistically significant difference (p=0.006). The corresponding measurements for hAPD before and after hydration were 14.5±3.6 mm and 14.6±3.4 mm respectively (p=0.846). Parenchymal thickness before and after hydration were 7.2±0.53 and 6.9±0.44 respectively which also showed no statistical significance (p=0.335). Hydration was found to have no significant effect on the parameters examined of contralateral kidney. Conclusion: The commonly used ultrasonographic parameters in the follow-up examination of hydronephrotic kidneys are prone to hydration effects. Among these parameters hAPD seems to be less affected. Copyright © 2013 by Türkiye Klinikleri.