Factors predicting improvement of renal function after pyeloplasty in pediatric patients: a prospective study

We assessed the specific preoperative sonographic and urinary factors that may be important in predicting renal function outcomes after pyeloplasty.

We prospectively studied 52 consecutive patients with ureteropelvic junction obstruction who underwent pyeloplasty at our tertiary care center between September 2009 and January 2011. Mean ± 2 SD patient age was 4.26 years (range 3 months to 18 years), and minimum followup was 6 months. Preoperative ultrasound findings recorded were pelvic anteroposterior diameter, pelvic cortical thickness, pelvic volume and pelvic cortical ratio. Spot urine protein-to-creatinine ratio from the renal pelvis and bladder was measured intraoperatively. Based on changes in differential renal function on diuretic renogram, patients were divided into 3 groups. Group 1 had stable differential renal function with less than 5% change, group 2 had improved differential renal function greater than 5% and group 3 had deterioration of differential renal function greater than 5%. Data were analyzed using SPSS®, version 17 with cross-tabulation, nonparametric tests and logistic regression.

On ultrasound only anteroposterior diameter (p = 0.018) and pelvic cortical ratio (p = 0.038) were significantly different among the 3 groups. Difference in bladder sample protein-to-creatinine ratio was not significant (p = 0.69), while pelvic urine protein-to-creatinine ratio was significant (p = 0.001). Anteroposterior diameter, pelvic protein-to-creatinine ratio and pelvic cortical ratio were less than 50 mm, 0.5 and 15, respectively, in all patients with improved renal function.

Sonographic and urinary biochemical parameters may predict improvement in renal function after pyeloplasty. Pelvic anteroposterior diameter, pelvic cortical ratio and pelvic urine protein-to-creatinine ratio are the most useful parameters.