Incidental detection of nutcracker phenomenon on multidetector CT in an asymptomatic population: prevalence and associated findings.

OBJECTIVE

To determine the prevalence of nutcracker phenomenon (left renal vein compression by the superior mesenteric artery) and secondary anatomic findings using multidetector computed tomographic (CT) angiography in an asymptomatic population.

METHODS

Ninety-nine consecutive CT angiograms for potential renal transplant donors (mean age, 39.0 years; 42 males) without variant renal vein anatomy were reviewed retrospectively. The diameters of the maximal left renal vein, left renal vein between the aorta and superior mesenteric artery, and draining gonadal and lumbar veins were measured. Sex, age, hematuria, proteinuria, and abdominal or flank pain were recorded.

RESULTS

Twenty-three patients had 50% to 70% stenosis, and 4 patients had greater than 70% stenosis of the left renal vein. Dilated gonadal and lumbar veins were found in 16 and 28 patients, respectively. Four patients had hematuria. These findings were not significantly associated with left renal vein compression.

CONCLUSIONS

Nutcracker phenomenon and dilated veins originating from the left renal vein are common incidental CT findings and nonspecific for the diagnosis of nutcracker syndrome.