Asymptomatic Obstructive Ureterolithiasis Due to a Periureteral Venous Ring.

Background: Periureteral venous rings are a rare congenital anomaly involving the inferior vena cava (IVC) and the right ureter, where the ureter courses through a venous ring made by the duplication of the IVC during embryogenesis. This anatomic anomaly is also referred to as a transcaval ureter. Although most patients are asymptomatic and radiographic findings are incidental, some patients can be symptomatic. We present the first reported case of asymptomatic obstructive ureterolithiasis at the level of a periureteral venous ring that was effectively treated with endoscopic management. Case Presentation: A 47-year-old woman was found to have right hydroureteronephrosis on MRI. Further CT imaging showed an obstructing ureteral stone at the level of a periureteral venous ring. After initial decompression with ureteral stenting, she underwent ureteroscopy that revealed the ureteral stone at the level of the venous anomaly. The stone was fragmented and removed with laser lithotripsy and stone basket manipulation. After a period of ureteral stenting and removal, she had improved hydroureteronephrosis, no symptoms of ureteral obstruction, and stable renal function. Given these findings, she elected for surveillance with imaging in lieu of any reconstructive procedure to transpose the ureter around the venous anomaly. Conclusions: We present the first reported case of obstructive ureterolithiasis at the level of a periureteral venous ring. Our experience suggests that, with preoperative ureteral stenting, obstructing ureteral stones in the setting of an IVC anomaly can be managed with retrograde flexible ureteroscopy. Conservative laser settings and minimal torqueing of the ureteroscope are advised given adjacent vascular anomaly. Cases wherein the affected ureteral segment is too constricted or tortuous to allow for stone passage or for ureteroscopy may require management by percutaneous antegrade intervention. Surgical reconstruction of the ureter should also be considered.