To prospectively evaluate per operative renal biopsy as a predictor of outcome of pyeloplasty in cases of unilateral pelviureteric junction obstruction in adults.

We conducted a prospective study on 24 patients with unilateral UPJ obstruction undergoing pyeloplasty between November 2005 and August 2006 and followed them until December 2010. Intraoperative renal wedge biopsy was obtained in these patients and this was correlated with preoperative DRF on diuretic renogram. Outcome of pyeloplasty was assessed at 1 and 3 years by diuretic renograms and the renal biopsy as a predictive tool was compared with preoperative DRF.

Histology suggestive of obstructive damage to kidneys, such as significant glomerulosclerosis, widened Bowman's capsule, interstitial fibrosis, and tubular atrophy on renal biopsy was the highly significant predictor of poor outcome of pyeloplasty with a P value = .001 compared with preoperative DRF.

Renal biopsy is better predictor of outcome of pyeloplasty compared with preoperative DRF in UPJ obstruction. In the presence of severe obstructive changes in renal biopsy, recoverability of renal function despite achievement of successful drainage is significantly decreased.