An Unusual Obstruction of the Left Renal Vein Caused by “Nutcracker” Phenomenon: Repair by Renocaval Bypass Procedure

Abstract

Compression of the left renal vein (LRV) between the superior mesenteric artery (SMA) and the aorta has been termed the nutcracker phenomenon. Although often asymptomatic, this phenomenon rarely results in hematuria and flank pain. The mechanisms of the compression found in the surgical cases have included a simple compression by the SMA, the fibrous tissue entrapping the LRV, and dorsal ptosis of the left kidney. Previous surgical approaches have thus included division of the fibrous band, renocaval reimplantation or external stenting procedures, and medial nephropexy. The authors report a case of a twenty-eight-year-old woman who had suffered from massive hematuria with resultant anemia and intractable flank pain caused by nutcracker phenomenon, which had resulted in unusual organic obstruction of the lumen of the LRV by intimal adhesion. Renocaval bypass with a prosthetic graft with supplemental nephropexy and resection of periureteral varices were successfully performed. The pathogenesis of the fibrous band and intimal adhesion could be considered to be the results of reactions to the mechanical stress by the SMA. Dorsal renal ptosis may be an additional contributing factor. Conclusion on the indications for excision of the pelviureteral varices awaits further surgical experiences.