Nutcracker syndrome: an overlooked cause of hematuria.

Nutcracker syndrome is caused by compression of the left renal vein between the aorta and the superior mesenteric artery, where it courses in the fork formed at the bifurcation of these arteries. The phenomenon results in left renal venous hypertension, which leads to left renal vein and left gonadal vein varices and unilateral hematuria. The main presenting symptom is hematuria, with or without left flank pain. The disorder is easily missed by routine diagnostic methods. Its incidence is likely underestimated. We report on a 25-year-old woman who experienced intermittent gross hematuria and left flank pain. The diagnosis of nutcracker syndrome was missed initially. Abdominal computed tomography, angiography, venography, and magnetic resonance angiography, which were later performed, showed that the left renal vein was compressed between the aorta and the superior mesenteric artery. The pressure gradient between the left renal vein and the inferior vena cava was 6.8 cm H2O. A diagnosis of nutcracker syndrome was established. She refused surgery and was lost to follow-up. The diagnosis and treatment of nutcracker syndrome are discussed. Magnetic resonance angiography is a safe and reliable tool for diagnosing this disorder.