Presentation
Sudden onset left flank pain. No past medical history.
Patient Data



Erect and supine abdominal x-rays. A cluster of calcifications is identified just lateral to the left L2 spinous process. The adjacent soft tissue contour has the appearance of a kidney, however, is more medially located than would be expected.



There is continuity of the renal parenchyma across the midline, in keeping with a horseshoe kidney. The cluster of calcifications seen on the x-ray is confirmed to be in the left renal pelvis. The left ureter is dilated, due to an obstructing calculus located just proximal to the vesicoureteric junction.



Delayed CT IVP images demonstrate the two halves of the horseshoe kidney joined at a parenchymal isthmus. There is sharp delineation between the normally excreting right kidney, and the delayed nephrogram of the obstructed left kidney, with virtually no excretion into the left collecting system.



Annotated x-ray findings
Case Discussion
Horseshoe kidney with ureteric calculus causing unilateral obstruction with a delayed nephrogram.