A 70 year old man, a domicile, contacted an Urologist of the University Hospital of the Clinical Center in Banja Luka for intermittent pains in the left side with irradiation towards the front, bottom and medially, which lasted for the last 10 days, which were also accompanied, in the last few days, with swelling of the abdomen and constipation, without giving anamnestic data about the reduction of the quantity of urinated urine. Two years before, the patient underwent a transurethral resection of the prostate because of chronic urine retention caused by a benign hyperplasia of the prostate, and, when a malfunction of the right kidney was verified (a relative function of it was 8.2%). Having performed the physical check, it was found out that the meteorism of the abdomen and pain of the left side when touched, with the rest of the general findings being NAD. In the initial diagnostic evaluation, laboratory tests of the blood and urine were done, ultrasonography of the abdomen and urinal tract and X-ray of the KUB. Serum analysis of the blood has shown the value of leukocytes to being 12.5, urea 82.3 mmol/l (normal range being 2.8-7.2 mmol/l), creatinine 2130 µmol/l (normal range 62.0-106.0 µmol/l), potassium 6.6 mmol/l (normal range 3.5-5.1 mmol/l), chlorides (Cl) 94 mmol/l (normal range 98.0-107.0 mmol/l), phosphates 3.93 mmol/l (normal range 0.87-1.45 mmol/l), CRP 125.6 mg/L (normal range (0.0-5.0 mg/L), uric acid 409 µmol/l (normal range 202.0-416.0 µmol/l), and acido-alkaline status of the metabolic acidosis, i.e. pH of the blood 7.124, BE-19.3 mmol/l and BF (ecf)-20.9 mmol/l. Ultrasonography of the abdomen and urinal tract has shown hypotrophy of the right kidney, without the presence of focal lesions, calculosis and hydronephrosis, as well as compensatory hypertrophy of the left kidney with hydronephrosis grade I/II, and in the projection of one of the calyces of the lower group hyperechoic zone of size 7 mm with acoustic echo. X-ray of the KUB, because of the expressed meteorism, has not shown positive mineral shadows in the projection of the left half of the upper part of urinal tract. The initial therapy approach included an acute hemodialysis in the first three days of hospitalization, as well as application of a wide-spectrum antibiotics, diuretics and other anti-hypertensive therapies with medicament correction of the acid-alkali status with a remaining symptomatic therapy with positive clinical effects, and, after stabilization of a general situation, the drop of nitrogen substances and correction of the acid-alkali status. On the fourth day of hospitalization, a left-sided ureteroscopy using a semi-rigid ureteroscope was done, and it has shown the presence of ureterolith below the pyeloureteric neck of the size of about 8 mm and, when attempted to do endocorporeal lithotripsy using a pneumatic lithotripter, the stone migrated (got pushed-up) into the kidney, after which a DJ stent was installed at 5CH. In further post-intervention period, the nitrogen substances, blood electrolytes, acid-alkali status and infection parameters got stabilized, with a sterile urine culture. The control KUB shown the position of the DJ stent to be correct and also, less visible, 2 mineral shadows in the projection of the lower pole of the left kidney, of 7 and 8 mm size (). CT urography showed that the longitudinal diameter of the right kidney was 7.4 cm, a significant reduction of the parenchyma, without the presence of focal lesions, hydronephrosis and calculosis, as well as a longitudinal diameter of the left kidney being 13.2cm, and in the projection of the lower pole an oval nephrolith of 7 and 8 mm, as well as the correct position of the placed JJ stent (). The hospitalization lasted for 16 days. Two weeks after hospitalization, there were 4 instances of extracorporeal lithotripsy performed on out-patient basis, with the Siemens lithotripter that produces shock waves by electromagnetic vibration of the metallic membrane, with the satisfactory destruction of the described nephroliths, but slowed emission of the fragments from the lower kidney pole. After the last ESWL treatment, an asymptomatic urinary infection was verified, and the urine culture showed the causative agent to be Acinetobacter 10/5, so the adequate antimicrobial therapy was administered and the indication for DJ stent removal/replacement was decided. The control of native urinary tract has not shown the absolute presence of mineral shadows in the projection of the urinary tract (). Ultrasonography verified acoustic echo in the projection of the proximal part (pig-tail) of ureteral stent. According to that, 2.5 months after the initial placement of the DJ stent, the urethrocystoscopy was performed under general anesthesia with the aim of DJ stent removal, and it showed that the distal part of the stent was macroscopically fine, without encrustation signs, but when tried for extracting the stent, there was the encrustation around the ureteral part of the stent that was inside ureter, and it was impossible to extract it. The next was the somewhat difficult introduction of the semi-rigid ureteroscope into intramural and juxtavesicular part of the left ureter that showed the presence of the compact film encrustation of DJ stent on its whole length. The lithotripsy of the encrustations in the mentioned part of the ureter was performed, and the fragments looked like the egg shell. During the mentioned intervention it was not possible to remove the ureteral stent. Extracorporeal lithotripsy in the projection of the proximal part of JJ stent was performed the next day, although mineral shadows were not visible by fluoroscopy. During the hospitalization the hydronephrosis grade II developed and nitrogen materials increased (urea 16, creatinine 343, potassium 5.5), and even with the satisfying diuresis uric acid increased to 809 umol/l, allopurinol was administered and percutaneous nephrostomy was performed. After the stabilization of the nitrogen substances levels, repeated ureteroscopy with additional extracorporeal lithotripsy of the encrusted stent was performed and the stent was successfully removed. The patient was discharged with percutaneous nephrostomy catheter, and the readmission was scheduled in 10 days in order to perform indicated anterograde pyeloureterography, which has shown defects in contrast filling in the lower lumbar and iliac part of the ureter, described as encrustation fragments. Repeated ureteroscopy with contact disintegration of the remaining fragments was performed. During the following days, the diuresis was forced parenterally and per orally, with temporal closure of nephrostomy catheter with the aim of better migration and spontaneous elimination of the remaining fragments, with positive clinical effect. The control anterograde pyeloureterography did not show the presence of remaining fragments, the closure of the nephrostomy catheter did not show the presence of hydronephrosis and increase of nitrogen materials, so the nephrostomy catheter was removed ().