Functional outcomes post pyeloplasty in solitary renal units. Structured analysis with the implication of AKIN staging criteria to predict long term renal function recoverability.

OBJECTIVES To assess the long-term functional outcomes post pyeloplasty in solitary kidney (SK) models and to define factors affecting postoperative renal function recoverability in adults. MATERIALS AND METHODS A retrospective evaluation of all adult patients who underwent pyeloplasty for UPJO in SK was done. Long term renal function was assessed by diuretic scintigraphy and morphological changes were also determined e.g.: renal parenchymal volume (RPV), parenchymal thickness (PT). We considered >20% GFR increase as improvement, >20% decrease as deterioration, and changes within 20% as stationary renal function. Univariate and multivariate analysis for factors affecting renal function recoverability including the AKIN staging system postoperatively were performed. RESULTS The study included 62 patients with a mean ± SD age of 29 ± 10.5 years. At a median of 48 months, the mean ± SD GFR increased from 41.3 ± 17 to 48.5 ± 20.1 ml/min (P < 0.0001) with a significant increase in RPV and PT (P = 0.02 and 0.001, respectively). Follow up renal function was static, improved and decreased in 39 (63.4%), 17 (27%) and 6 (9.6%) patients, respectively. Functional success was achieved in 90.4%. Patient's age ≥ 39 years, PT ≤ 0.75 cm and higher early postoperative AKIN staging were predictors associated with 4.8, 3.2 and 2.7 folds of renal function deterioration. CONCLUSION Pyeloplasty in SK could preserve renal function in 90.4 % of patients. Pyeloplasty in solitary functioning kidneys associated with older age, decreased PT preoperatively and early higher AKIN staging postoperatively were associated with poor renal function recoverability.