Robot-Assisted Partial Nephrectomy via a Retroperitoneal Approach With Selective Arterial Clamping Guided by Blood Flow Analysis in a Horseshoe Kidney: A Case Report.

Introduction: Horseshoe kidney is the most common congenital renal fusion anomaly and is associated with aberrant anatomy and a complex vascular supply, which can complicate nephron-sparing surgery. Case Presentation: A 43-year-old woman was incidentally diagnosed with a small hypovascular tumor in the right renal moiety of a horseshoe kidney. Three-dimensional computed tomography with blood flow analysis using SYNAPSE VINCENT (Fujifilm, Japan) demonstrated that the tumor was supplied exclusively by the upper pole renal artery. Because the right renal moiety was largely covered by the liver, a conventional midaxillary retroperitoneal approach was unsuitable, and the retroperitoneal space was established via a pararectus approach. A hybrid laparoscopic-robotic technique was adopted due to the limited working space. Conclusion: Preoperative blood flow analysis enabled selective arterial clamping, and a tailored surgical approach allowed safe robot-assisted partial nephrectomy with minimal blood loss and preserved renal function.