[Encrustation and stone formation in double J ureteral stent: report of two cases].

We recently experienced two cases of encrustation and stone formation on double J ureteral stent which had been indwelt at pyeloplasty and at pyelolithotomy. In these patients, bacteriuria and pyuria had continued. Encrustation and stone formation were recognized by follow-up X-ray fairly soon after operation. Judging from our experience, encrustation and stone formation should be suspected in patients with persistent bacteriuria and/or pyuria and who have episodes of urolithiasis. To avoid encrustation and stone formation, the ureteral stent should be replaced more frequently.