[Endoscopic and percutaneous treatment of purulent retention caused by obstructive calculi of the upper urinary tract. Observations apropos of 6 case reports].

On the basis of 6 cases of pyonephrosis due to renal stones successfully treated without surgery over a period of one year, the authors define their current therapeutic approach which consists of 2 phases: --1st phase: salvage of the kidney by ultrasound guided percutaneous nephrostomy under local anaesthesia. No hasty endoscopic procedures in an attempt to insert a ureteric catheter into the kidney; --2nd phase: elimination of the obstructing stone (on average, 8 days after the 1st phase), by percutaneous nephrolithotomy, descending ureteroscopy or ascending ureteroscopy.