Patients with upper ureteral or renal stones will be randomized to undergoing ureteroscopy with or without a ureteral access sheath. The sheath is designed to facilitate ureteroscope insertion and re-insertion, thus allowing fragments to be basketed out. Stone free rates at 3 months will be determined between the two groups.

The investigators hypothesize that the use of the ureteral access sheath with ureteroscopy will result in improved stone free rates at 3 months compared to ureteroscopy without use of a sheath.

Inclusion Criteria:

• Upper ureteral (proximal to iliac vessels/iliac crest) calculi;
• Renal calculi;
• ASA class I or II;
• Normal renal function;
• Any stone composition;
• Single or multiple stones (planned treatment of all stones at this surgery);
• Age > 18 years;
• Able and willing to return treatment centre for follow-up visits; AND
• Signed study consent

Exclusion Criteria:

• Ureteric calculi distal to the level of the iliac vessels/iliac crest;
• Failed ureteroscopy for same stone (i.e. has to be the first ureteroscopic procedure for this stone, however a prior failed extracorporeal shockwave lithotripsy (SWL) is acceptable);
• Bilateral ureteroscopy;
• If an adjunctive procedure is planned post ureteroscopy (e.g. percutaneous nephrolithotomy, SWL) (i.e. it is known preoperatively that a ureteroscopic procedure will not render the patient stone free and that ancillary procedures will be necessary);
• If in the investigators opinion, enrollment would be not be appropriate; OR
• Pregnancy