The Most Appropriate Imaging Analysis in Pyelonephritis and Its Complications: Clinical Evidence.

<b>Background.</b> Although renal ultrasound or computed tomography (CT) without contrast may allow the diagnosis of complicated acute pyelonephritis (PN), they may fail to diagnose renal abscesses and complicated PN, which is allowed by the upper level imaging: contrast CT or Nuclear Magnetic Resonance (MRI). <b>Case presentation.</b> We report three clinical cases of patients admitted to the Nephrology, Dialysis and Transplantation Unit at Padua University Hospital in which renal ultrasound (US) and Computed Tomography (CT) without contrast failed to allow diagnosis of PN complications, while contrast CT showed renal abscesses in two patients and Nuclear Magnetic Resonance (NMR) without contrast a frank PN in one. <b>Conclusion.</b> Contrast CT or MRI should be preferred to renal US and/or CT without contrast and are the most indicated imaging analyses to be prescribed in acute complicated PN, in particular in the presence of acute kidney injury.