The "nutcracker" phenomenon: an unusual cause for renal varicosities with hematuria.

The "nutcracker" phenomenon refers to renal vein compression by the aorta and superior mesenteric artery where the vein courses in the fork formed at the bifurcation of these arteries. Renal varicosities with hematuria developed in our patient in response to obstruction of the renal vein at this site. Surgical exploration revealed the left renal vein to be compressed by and stretched over the abdominal aorta. This deformity was corrected by medial fixation of the kidney and excision of extensive renal varicosities involving periureteral and ovarian veins. The patient has experienced no further hematuria.