Flexible Ureteroscopy With and Without Ureteral Access Sheath in Treatment of Large Renal Stones: a Randomized Controlled Trial.

Treating a large renal stone, more than 2 cm, is changing during the last decades. Technological innovations have led to a significant improvement in flexible ureteroscopes over recent years.

Many authors have used flexible ureteroscope (FURS) with laser fragmentation as proved treating modality with high efficacy. Although percutaneous extraction of large renal stones is still the first option, it has higher and more severer complications than flexible ureteroscopy.

FURS has developed into a standard diagnostic and treatment modality for upper urinary stone disease, transitional cell carcinoma and ureteral strictures. Indeed, more recently FURS is becoming a minimally invasive competitor to percutaneous nephrolithotomy for larger kidney stones as well as an accepted modality for localized treatment of small upper urinary tract transitional cell carcinoma.

The use of ureteral access sheath (UAS) is widely recognized as a technique utilized to keep the intrarenal pressure low when performing FURS for larger and more complex stones, although some authors advocate its use for most renal stones. UASs are now produced with varying characteristics including various lengths, diameters, materials, dilator tip designs, radiopaque markers, and stiffness. However, it also rises surgical costs and may injure the ureteral wall.

Most common reasons cited by urologists for using a UAS are to facilitate repeated entrance into the ureter and collecting system (as a time-saver), lower intrarenal pressure and protection of ureteroscope and ureter when extracting stone fragments. UAS has encouraged urologists in the fragmentation of large stones; it facilitates multiple entries and stone extraction during FURS.