Differentiation of Malignant From Benign Distal Ureteral Obstructions

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The purpose of this study was to evaluate the feasibility of transrectal ultrasonography (TRUS) and color Doppler ultrasonography (CDUS) in differentiating malignant from benign distal ureteral obstructions. Our study group consisted of 16 malignant distal ureteral obstructions and 12 benign distal ureteral obstructions. The 16 malignant distal ureteral obstructions were transitional cell carcinomas involving the distal ureter. The 12 benign distal ureteral obstructions consisted of benign strictures (n = 4), ureteral edema after stone passage (n = 3), tuberculosis (n = 2), a fibroepithelial polyp (n = 1), amyloidosis (n = 1), and a hematoma (n = 1). Findings from gray scale transabdominal ultrasonography, gray scale TRUS, CDUS, and duplex Doppler imaging were retrospectively evaluated. Gray scale transabdominal ultrasonography and TRUS showed no specific difference between malignant and benign distal ureteral obstructions. On CDUS, malignant distal ureteral obstructions showed dotlike blood flow in 5, moderately increased blood flow in 9, and markedly increased blood flow in 2; and benign distal ureteral obstructions showed absence of blood flow in 5 and dotlike blood flow in 7. Flow spectra could be obtained in 12 malignant distal ureteral obstructions, and they showed arterial waveforms. Duplex Doppler imaging was not tried in 4 malignant distal ureteral obstructions. In 7 benign distal ureteral obstructions with dotlike blood flow, flow spectra could not be obtained. Moderately or markedly increased blood flow within a ureteral mass on CDUS and an arterial waveform within a ureteral mass on duplex Doppler imaging may be helpful in differentiating malignant from benign distal ureteral obstructions.