Outcome analysis of pediatric pyeloplasty in units with less than 20% differential renal function.
OBJECTIVE
This study was conducted to assess ureteropelvic junction obstruction (UPJO) units with differential renal function (DRF) ≤20%, 3 months post-pyeloplasty as well as complications and stability of function in long term follow up.


MATERIAL AND METHODS
In this prospective study, children below 12 years age with unilateral UPJO and DRF ≤20% undergoing open Anderson-Hynes dismembered pyeloplasty from 2002-2014 excluding associated vesicoureteric reflux were included. Drainage and function were assessed with isotope [ethylene di-cysteine (EC)] scan at 3 months and later during yearly follow-up as well as by intravenous urography (IVU).


RESULTS
Of a total 744 patients with UPJO in the study period, 112 had DRF ≤20%. Thirty four (30%) underwent percutaneous nephrostomy. Ten with no function underwent nephrectomy. 102 (mean age 4.7 years) with DRF 0-9% (n = 40) and 10-20% (n = 62) formed the study group. Hypertension (3), small kidney (13) and crossing vessels (9) were associated. Follow up ranged from 1-8 years (4.6 ± 1.34 years). Six patients were lost to follow up. There was significant improvement in drainage in the remaining 96 patients. Mean DRF and IVU function showed highly significant improvement (p < .001) in those with clinical signs and symptoms (n = 85), compared to asymptomatic patients in preoperative 0-9% and 10-20% group. The mean rise in DRF was significantly more in the preoperative 0-9% group, palpable mass presentation and by age at 5-12 years in the 0-9% group and 1-5 years in the 10-20% group. In the symptomatic group, except for intermittent UTIs (n = 8) and pain (n = 3) which subsided 1-2 years after surgery, all patients had resolution of initial complaints. Hypertension resolved in two patients with crossing vessels. No patient required re-do pyeloplasty or developed hypertension during followup. There was no significant difference (p = 1.000) in mean DRF between 3 month and 1-8 years post-operative scans (n = 53).


CONCLUSIONS
This study which appears to be the largest in the literature of pediatric UPJO with DRF ≤20%, conclusively shows that there is statistically significant improvement in function after pyeloplasty which remains stable during the period of growth with no long term complications. Nephrectomy should be considered only in patients with nil or <5% uptake on isotope imaging with associated (a) no parenchyma on imaging or on exploration, (b) pyonephrosis, (c) hypertension or (d) minimal urine output on percutaneous nephrostomy.