Images in clinical medicine. Stent-associated urinary calculi.

摘要

A 54-YEAR-OLD MAN WAS REFERRED BECAUSE OF A 6-MONTH HISTORY OF LOWER URINARY TRACT SYMPTOMS, microhematuria, and dull pain in the right flank. He had undergone shock-wave lithotripsy for the treatment of a 20-mm renal stone on the right side 12 years earlier. At that time, a double pigtail stent had been inserted after successful stone disintegration. However, the patient did not return for follow-up to have the stent removed. During the years after the stent placement, he had a few intermittent urinary infections. Plain radiography of the kidneys, ureters, and bladder showed a calcified double pigtail stent (solid arrows) with a fragmented intravesical portion (open arrow) and a large bladder stone (arrowhead). Renal radionuclide imaging showed loss of renal function in the affected kidney. The patient underwent right nephroureterectomy and cystolithotomy. His recovery was uneventful. Chemical analysis confirmed that the stone was composed of calcium oxalate and calcium phosphate. Pigtail stents are used for temporary urinary drainage and prevention of ureteral obstruction for up to 6 weeks after lithotripsy. Unretrieved stents can become a nidus for stone formation, renal obstruction, urinary infection, and impairment of renal function.