Horseshoe kidney with multiple bilateral renal calculi (these kidneys are prone to stone formation due to relative urinary stasis). Note stones towards the lower pole of the right kidney with marked dilatation of the right renal pelvis and calyces, and considerable surrounding soft tissue swelling (caused by the sepsis). These 2 right stones (arrows) are in the malrotated PUJ passing anteriorly rather than medially, causing obstruction.