Diuretic radionuclide renography in assessing Anderson-Hynes pyeloplasty in unilateral pelviureteric junction obstruction.

The topic of whether improvement can be expected after pyeloplasty in patients with pelvi-ureteric junction obstruction (PUJO) continues to generate debate. The aim of this study was to analyse the functional outcome of unilateral Anderson-Hynes (A-H) pyeloplasty using differential renal function (DRF) and drainage patterns determined by diuretic radionuclide renography (DRR). A retrospective study was carried out by evaluation of the records of patients who underwent A-H pyeloplasty for unilateral PUJO and reported for a follow up renal dynamic scan between the years 2000 and 2003. A total of 126 patients (93 males and 33 females) aged three months to 40 years had undergone pre-operative and post-operative DRR and were followed for at least six months after operation. For comparison, the renal function prior to and after pyeloplasty was classified into three Groups based on the DRF: Group A: > or = 40% DRF 52 patients, Group B: 20%-39% DRF 65 patients and Group C: < 20% DRF 9 patients. The difference between pre-operative and post-operative DRF in the last follow up study, which ranged from six months to 144 months after operation, was calculated for each patient. To account for an accepted error of measurement, an absolute difference in DRF of more than 5% was considered significant. Improvement in drainage was assessed by the time Tmax 1/2 of the renographic curve. Unpaired t test was applied between Group A and Group B patients. Chi square analysis was applied to estimate the proportion of improvement between Groups A and B. Post-pyeloplasty scans revealed stable renal function in 102 (81%) subjects, while improvement was noticed in 14 (11%) subjects. The remaining 10 (8%) subjects had deterioration in renal function. No improvement in renal function was seen in Group C patients. Our results have shown that in the majority of cases studied, after A-H pyeloplasty renal function remains stable. A-H pyeloplasty applied in patients with preserved DRF and obstruction will result in long term preservation of renal function.