Diagnosis of renal transplant failure by real-time and duplex Doppler sonography.

A total of 419 real-time and duplex Doppler ultrasound examinations of renal allografts were carried out in 61 patients. Results were related to the clinical diagnoses based on histomorphological, clinical, and laboratory findings. The results of all sonographic examinations in terms of the diagnostic parameters of normal function, acute tubular necrosis, and interstitial and vascular rejection did not yield reliable criteria for distinguishing between the different forms of transplant dysfunction. The maximum difference was calculated for each ultrasound parameter between a time of normal transplant function and at a time of dysfunction. By means of this 'maximum parenchyma-pyelon index difference' it was possible to discriminate between acute tubular necrosis and vascular rejection (P < 0.05). Acute tubular necrosis could be distinguished from interstitial rejection using the maximum longitudinal renal diameter difference and the maximum parenchyma-pyelon index difference (P < 0.05). To discriminate between interstitial and vascular rejection the maximum pulsatility index difference was very useful (P < 0.05). Combined real-time and duplex Doppler sonography is most valuable in the diagnosis of transplant failure when it is performed not only in the case of dysfunction but also when transplant function appears to be normal.