After shock wave lithotripsy and endoscopic lithotripsy, occasionally a patient has persistent ureteral fragments associated with ureteral obstruction. After lithotripsy, stone fragments may be embedded in the ureteral mucosa, and they may become completely submucosal and associated with obstruction. Others may be hidden in iatrogenic ureteral outpouchings, while still others may be extruded from the ureter entirely. We present 20 patients who were referred after previous treatment failed to clear fragments or who had residual obstruction. The majority of patients had failed endoscopic fragment retrieval or shock wave lithotripsy and were referred with ureteral obstruction. All patients were reevaluated by repeated upper tract endoscopy with small diameter endoscopes. As an adjunct to ureteral endoscopy, a 6F, 20 MHz. ultrasound probe was placed transureterally to determine the depth and location of stones. A total of 15 patients in this series had hyperechoic foci with shadowing consistent with submucosal or periureteral stone fragments. A decision for treatment was based upon the location as noted by sonographic and fluoroscopic visualization of intramucosal and submucosal fragments. Calculi more than 4 mm. from the lumen were not removed without evidence of obstruction. Multiple, small (speckled) fragments embedded in the mucosa were often associated with subsequent stricture. Solitary fragments within the wall of the ureter could be removed with relief of obstruction. The risk of embedding calculi submucosally during lithotripsy should be recognized. Submucosal fragments causing obstruction should be removed endoscopically. Totally extruded calculi may be left in situ safely.