The place of retroperitoneoscopic hemi-nephroureterectomy for duplex kidney in children; risk of damage to the remnant moiety and strategies to reduce the risk

Abstract

To analyse the outcomes of retroperitoneoscopic upper and lower moiety hemi-nephroureterectomy (HNU) and to assess the different variables that may have an impact on outcome; remnant moiety damage, morbidity and the need for secondary surgery. Prospectively recorded data of retroperitoneoscopic HNU's performed by a single surgeon from 2005 to 2018 were analysed. Patients were split into 2 groups according to moiety affected (UMHNU and LMHNU). Clinical presentation, underlying pathology, remnant moiety DRF on renal scintigraphy, and need for further surgery were recorded. Detailed operation notes were studied regards to renal vasculature, degree of dilatation, inflammatory changes and operative difficulties encountered. Renal loss was defined as remnant moiety DRF <10% post-operatively. Change in DRF was assessed regards to the moiety, pathology and age at surgery (<1 year, 1-2 years and ≥2 years). UMHNU group was further sub-divided into 3 subgroups: ureteroceles, ectopic ureters and 'other' pathology. Statistical analysis was performed using Fishers Exact test; findings were considered statistically significant at p<0.05. 78 operations met the inclusion criteria on 75 patients (3 bilateral). There were no conversions to open, and 67% were performed as day-case procedures (53/78 patients). In 91.2% (71/78) patients the procedure was definitive in resolving pathology and symptoms. 7 patients needed further procedures after HNU, 5 for ureterocele/ureteric stump. Overall, there was remnant moiety renal loss in 5.1% (4/78) patients, all with UM surgery (3 ectopic ureters and 1 ureterocele). All 4 operations were recorded prospectively as 'difficult operations' due to grossly dilated UM ureter/pelvis measuring >2cm in diameter. 2 patients had a thinned out lower moiety (LM) sitting on top of the UM renal pelvis like a pancake with all vessels stretched over this dilated pelvis/ureter causing difficulty in accurate identification. There was intra-operative concern about some damage to LM vessels in 3 patients. Age <1year was also related to increased renal loss (2/8 patients <1 year, 1/25 patients 1-2 years, 1/45 patients ≥2 years of age P=0.005). Retroperitoneoscopic LMHNU is a safe and definitive procedure with rapid recovery and minimal scarring. UMHNU has higher rates of remnant moiety loss due to more complex renal pathology, but remains a safe, successful operation on the majority of patients. Renal damage was also related to age <1year (p=0.005) and re-operation risk after UMHNU correlated to the presence of ureterocele (p=0.003).