Renal arteriovenous malformation mimicking hydronephrosis.

Color and spectral Doppler sonography revealed that a patient believed to have hydronephrosis actually had a renal arteriovenous malformation. Although rare, such a misdiagnosis could have serious implications. In the case described here, there was a coexisting carcinoma of the colon, which required staging and could have led to complications for percutaneous intervention. This case illustrates that color Doppler sonography can be used to establish a diagnosis of arteriovenous malformation.