Aim: Whether off-clamp nephron-sparing surgery serves to prevent ischemic damage of the operated kidney and is associated with a better renal function preservation remains uncertain. The aim of present study was to evaluate in children with renal tumor the magnitude of functional decline of the operated kidney after zero-schemia nephron-sparing surgery (Z-NSS).
Patients and Methods: Of 50 children treated at our institution for Wilms tumor between 1992 and 2016, 15 (30%) children underwent NSS. One patient with bilateral metachronous Wilms tumor, one patient who underwent an unnecessary nephrectomy elsewhere and one underwent nephrectomy for a recurrent Wilms tumor were excluded from analysis. Remnant kidney function was assessed with Tc-dimercapto-succinic acid renal scintigraphy (DMSA). Remnant kidney volume was assessed with renal ultrasonography (USS) and/or magnetic resonance imaging (MRI). We considered 40% split renal function or split renal volume as the lowest normal value.
Results: A positive correlation between split renal function and split renal volume was found (p=0.001).The subset of patients with >40% preservation of operated kidney renal function presented with a not- time dependent renal function up to the adolescence. The subset of patients with < 40% preservation of operated kidney renal function presented with a progressive increase in renal function and volume that during adolescence reached values not much different from those with >40% preservation of the operated kidney function. At mean last follow-up of 18 ± 2.72 years, mean total post-operative eGFR was 126.1±18.16 ml/min/1.73 m2 whereas pre-operative total renal function was 95.1±30.4 ml/min/1.73 m2 (p=0.01).
Conclusions: In our small cohort of children who underwent Z-NSS, USS proved to be an accurate and non-invasive method for measurement of split renal volume/ function. At long-term follow-up after Z-NSS, children may present with an excellent compensatory kidney volume/function growth.