Does Hynes-Anderson pyeloplasty improve renal function?

INTRODUCTION: With the advent of renoscintigraphy, improvement in renal function after Hynes-Anderson pyeloplasty became and continues to be an object of interest. We performed a retrospective analysis in a group of our patients with the hope of resolving some issues. MATERIAL: Medical files with complete renoscintigraphic data of 51 patients with symptomatic hydronephrosis who underwent Hynes-Anderson pyeloplasty between 1996 and 2002 were analyzed. Two study groups were formed: patients operated before the age of 12 months (n = 18, mean age 4 months), and patients operated after the age of 12 months (n = 33, mean age 8 years). METHODS: Renoscintigraphic imaging was performed using DTPA according to EANM guidelines. The following parameters were analyzed: differential renal function--DRF (%), glomerular filtration rate--GFR (mL/min), and type ofrenoscintigraphy (1--non-obstructive, 2--equivocal, 3--obstructive). Renoscintigraphy was done preoperatively, 3 and 12 months after surgery, and at the end of the follow-up. The level of significance was taken as p < or = 0.05. RESULTS: Preoperative DRF values in both groups (46 +/- 8 and 44 +/- 9) revealed no significant differences; GFR values (18 +/- 14 and 36 +/- 17) revealed significant differences (p < 0.001) between the groups. 55% of patients in each group had obstructive renoscintigraphy (2.3 +/- 0.9 and 2.2 +/- 0.9, respectively). Preoperative and consecutive postoperative DRF values did not reveal any significant differences. A progressive increase in GFR was noted in infants: the change was insignificant after three months from surgery, becoming significant after 12 months (p = 0.007), and reaching 45.6 +/- 7.1 (p = 0.02) at the end of follow-up. No significant differences were found in older children. Significant improvement in drainage noted three months after surgery in both groups (1.6 +/- 0.9; p = 0.008 and 1.4 +/- 0.8; p = 0.001) did not reveal any further change. CONCLUSIONS: 1. Hynes-Anderson pyeloplasty had no effect on DRF values in most patients regardless of age and initial renal function. 2. The increase in GFR in children operated before the first year of life seems attributable to the growth potential of the kidney, although surgery could have created conditions for full emergence of this potential. 3. Obstructive renoscintigraphy is not an unequivocal proof for clinically significant urine outflow obstruction; this can be demonstrated by clinical symptoms.