Clinical Indications and Procedures
The choice of scope is primarily determined by the location of the stone or pathology within the urinary tract.
Semi-Rigid Ureteroscopy (sr-URS)
Primary Use: Indicated for the distal (lower) and mid-ureter. Because the lower ureter is relatively straight, the rigid shaft can reach these areas easily.
Advantages: Better irrigation flow due to larger channels, superior push-and-pull maneuverability, and lower procedural costs.
Limitations: It cannot reach the kidney (renal pelvis/calyces) safely without risking ureteral perforation or trauma.
Flexible Ureteroscopy (f-URS)
Primary Use: Indicated for the proximal (upper) ureter and the kidney. It is the gold standard for Retrograde Intrarenal Surgery (RIRS).
Advantages: Can navigate the sharp "turn" into the kidney and reach all renal calyces. It is less traumatic to the ureteral lining.
Limitations: More expensive, requires specialized "ureteral access sheaths" to facilitate repeated entry, and has a slower irrigation rate which can sometimes impair visibility during bleeding.