Long-term functional renal outcomes after retroperitoneoscopic upper pole heminephrectomy for duplex kidney in children: a multicenter cohort study.

BACKGROUND: Retroperitoneoscopic upper pole heminephrectomy (RUHN) in duplex kidney in children remains a challenging procedure with a need for postoperative functional assessment of the remnant lower pole. We aimed to calculate the incidence of long-term functional renal outcomes in these children and examine the effect of age on those outcomes. METHODS: A multicenter retrospective cohort study of 9 years included all patients undergoing RUHN and evaluated by renal ultrasound (US) and dimercaptosuccinic acid (DMSA) scintigraphy pre and postoperatively. Patients were divided in two age groups of ≤12 and >12 months. Standard follow-up assessed pre-, intra- and postoperative outcomes using clinical review, US and DMSA. RESULTS: Standard RUHN in lateral position was performed in 30 patients. Five cases were excluded (2 lacks of postoperative DMSA, 3 conversions). Indications for RUHN were non-functioning upper moieties (n = 25) caused by ureterocele (n = 11), ectopic distal implantation of the ureter with incontinence (n = 6) or evolving severe ureterohydronephrosis (n = 8). Mean age at surgery was 30 ± 27 months, operation time 116 ± 52 min and hospital stay 2.8 ± 1 days. Long-term follow-up (mean, 7.2 ± 2.7 years) with US and DMSA showed that none of the 25 patients had complete loss of lower pole renal function. Mean lower pole renal function directly related to RUHN was not significantly different after versus before RUHN for the entire cohort (n = 24; 39.7 ± 7.90 % vs. 41.7 ± 6.74 %; p = 0350), for the ≤12-month (n = 6; 39.3 ± 4.18 vs. 41.3 ± 5.47; p = 0.493) and the >12-month groups (n = 18; 39.8 ± 8.90 vs. 41.9 ± 7.25; p = 0.443). Four patients (17 %) had partial loss of function (mean function loss, 9.3 ± 5.85 %; median age, 13 months). The number and type of complications between the two age groups were not statistically different. Overall, 29 % (n = 7/24) of the patients presented with medium-term (17 %) and long-term (17 %) complications directly related to RUHN. CONCLUSIONS: RUHN is a demanding yet efficient technique that is safe for the lower pole at any age. Systematic postoperative DMSA is not mandatory as long as US remains normal.