Our objective was to evaluate the accuracy of color Doppler sonography for assessing tumor thrombus extension into the renal veins, the inferior vena cava, and the right side of the heart in patients with renal cell carcinoma.Over the past 4.5 years, 44 patients with 46 renal cell carcinomas were examined with color Doppler sonography for the presence and extent of tumor thrombus in the renal veins, the inferior vena cava, and the right side of the heart. Examinations were performed after an equivocal CT scan in 34 patients and as a primary imaging technique in 10. Color Doppler sonographic findings were correlated with surgical-pathologic findings or findings from autopsies performed within 3 months of the Doppler study. Seven patients were excluded: two because of poor technical quality caused by body habitus and five because pathologic correlation was performed more than 3 months after the color Doppler sonographic examination. The remaining 39 renal vein and 37 caval Doppler examinations constituted t...