Infant with urinary tract infection Sagittal US of the right kidney (upper left) shows a duplicated renal collecting system with the upper pole replaced by a round structure filled with echogenic material. Sagittal US of the right upper pole ureter (upper right) shows a tortuous ureter filled with echogenic material. Transverse US of the bladder (lower left) shows a round structure in the right side of the bladder that has echogenic material in its inferior portion and anechoic material in its superior portion. Sagittal US of the right ureter and bladder (lower right) shows the tortuous right ureter filled with echogenic material on the left side of the image and the rounded structure with the fluid-fluid level in the right side of the bladder. The diagnosis was acute pyelonephritis in a duplicated kidney with an ectopic ureterocele with hydroureteropyonephrosis throughout the upper pole of the right kidney and right upper pole ureter and ureterocele.