Diagnosis of the nutcracker syndrome with color Doppler sonography: Correlation with flow patterns on retrograde left renal venography

OBJECTIVE. Our objective was to confirm flow patterns of the left renal Vein and assess the usefulness of color Doppler sonography in the diagnosis of the renal vein entrapment, or nutcracker, syndrome. SUBJECTS AND METHODS. Forty-four patients with hematuria of unknown origin underwent color Doppler sonography, renal arteriography, retrograde left renal venography, and renocaval pressure measurement. The flow patterns were classified according to the presence or absence of distended left renal veins on sonograms and collateral veins on retrograde venograms. The sensitivity and specificity of color Doppler sonography for revealing the nutcracker syndrome were assessed by analyzing pressure gradients in combination with the venograms, which were used as the gold standard. RESULTS. Twenty-one nondistended left renal veins were seen, including 19 (43%) without collateral veins or hypertension and two (5%) with collateral veins but without hypertension (long-term nutcracker syndrome). The 23 distended left renal veins included seven without collateral veins or hypertension and one with hypertension but without collateral veins (early nutcracker syndrome). The remaining 15 distended left renal veins with collateral veins included 11 (25%) with borderline hypertension (partially compensatory status of the Syndrome) and four (9%) with hypertension (noncompensatory status of the syndrome). The sensitivity and specificity of color Doppler sonography for revealing the nutcracker syndrome were 78% and 100%, respectively when color flow in collateral veins was included in the diagnostic criteria. CONCLUSION. The nutcracker syndrome can exist in either nondistended or distended left renal veins. However, normal flow also can exist in distended left renal veins. The ability of color Doppler sonography to reveal color flow in collateral veins is useful for the noninvasive diagnosis of the nutcracker syndrome.