Calcifying pyelitis: Puzzling sonographic appearance of urothelial calcifications in chronic urinary tract infection by urea-splitting bacteria

A 74-year-old male patient developed renal failure because of urinary obstruction

of his left kidney, the right kidney was atrophic. Computed tomography showed

nephro- and urolithiasis; sonography disclosed excessive calcinosis of the renal pyramids, after occlusion of an ureteral stent, also calcification or the renal pelvic urothelium could be visualized. An internet search (google) revealed encrusting

pyelitis as the probable cause of the calcifications, indeed, urinary pH was repeatedly increased, and microbiologic examination showed corynebacterium urealyticum urinary infection. Chronic urinary tract infection with urea-splitting bacteria results in ammonium formation with increased urinary pH, resulting in saturation with struvite as the cause of the precipitations. Antibiotic therapy failed to resolve the infection, local irrigation with acidification of the pyelon showed no effect, nephrectomy with resulting dialysis dependency had to be performed.

Fig. 1: Distented, calcified pyelon

Conclusion: In renal calciifications, chronic urinary tract infection with urea-splitting bacteria resulting in encrusting pyelitis has to be considered. Elevated urinary pH may be a clue to diagnosis. The combination of ultrasound equipment and internet access proved as a diagnostic “multitool”.