Genitourinary imaging with noncontrast computerized tomography--are we missing duplex ureters?

PURPOSE

Noncontrast computerized tomography has replaced excretory urography as the first line diagnostic tool for evaluating nephrolithiasis at many centers. We evaluated the ability of noncontrast computerized tomography to detect ureteral duplication to determine how frequently these anomalies are under diagnosed.

MATERIALS AND METHODS

Computerized tomography images of 14 patients with known ureteral duplication who had previously undergone noncontrast and contrast enhanced computerized tomography and 5 control patients with normal ureteral anatomy were interpreted by 2 blinded radiologists who specialize in genitourinary imaging.

RESULTS

The sensitivity of axial computerized tomography with contrast material, axial computerized tomography without contrast material and coronal computerized tomography without contrast material was 96%, 59% and 65%, respectively. The negative predictive value of axial computerized tomography with contrast material, axial computerized tomography without contrast material and coronal computerized tomography without contrast material was 95%, 65% and 67%, respectively. The accuracy of axial computerized tomography with contrast medium was significantly higher than that of noncontrast axial or noncontrast coronal computerized tomography (each p <0.01).

CONCLUSIONS

Duplicated ureters, which represent a challenge to the endourologist, are under diagnosed on noncontrast computerized tomography. Urologists and radiologists should be aware of this limitation and contrast studies should be done when anatomical anomalies are suspected.