Management of a Donor Supernumerary Kidney During Renal Transplantation: A Case Report

Introduction: A fused hilar supernumerary kidney was discovered in a donor organ upon reperfusion during renal transplantation. There is a paucity of literature regarding this anomaly and its management in renal transplant recipients. Case Presentation: Back table preparation of a right deceased donor kidney revealed a duplicated renal artery and ureter. Complex reconstruction of the vasculature was performed avoiding extensive hilar dissection. Following anastomosis of the renal vasculature to the recipient’s iliac vessels, reperfusion revealed a suspicious lower pole renal mass. Frozen section biopsies of the mass were consistent with normal renal parenchyma. Urology was consulted intraoperatively and confirmed the mass to be a small accessory kidney with a separate collecting system, thin parenchyma and hydroureteronephrosis. A nephrectomy of the supernumerary kidney was performed. Discussion: Supernumerary kidneys are extremely rare and infrequently encountered by transplant surgeons. They are usually asymptomatic and incidentally discovered on imaging. If discovered intraoperatively careful inspection must be performed to evaluate for stigmata of potential complications. Conclusion: Knowledge of this entity is important to provide crucial intraoperative decision making and management if encountered in a donor organ. Careful evaluation of these anomalies must be performed when considering resection in order to avoid later complications, with caution that resection may compromise renal function.