Fig. 2
A 28-year-old woman was admitted at 35 weeks of gestation presenting renal colic not responding to medical treatment. US images showed left hydronephrosis due to a 1-cm stone impacted at the level of the ureterovesical junction (a). A percutaneous nephrostomy was performed and the stone extracted (b). Two days after this procedure, the patient presented with fever and acute pain localized to the left flank. Ultrasound was unremarkable. The axial T2-weighted HASTE sequence (c) and axial T2-weighted fat-saturated sequence (d) show an enlarged edematous right kidney; focal areas of higher signal intensity on T2-weighted imaging could be due to focal infection. ADC map (e) shows restricted proton diffusion indicative of pyelonephritis