We proposed that silodosin administration preoperatively may facilitate ureteral access sheath (UAS) placement prior to flexible ureteroscopy (F-URS) and decrease the incidence of ureteric injury in some difficult cases.

Urolithiasis is a common urological disorder in the world and has a significant effect on the global health system. The goal of treatment is to achieve the highest stone-free rate (SFR) with the least invasive. Per¬cutaneous nephrolithotomy and flexible ureterorenoscopy (F-URS) are the two main minimally invasive procedures for the treatment of upper urinary tract stones.

The challenging step in flexible ureterorenoscopy (F-URS) is ureteroscopic access sheath (UAS) placement, which facilitates fast and safe access to the ureter and collecting system; improves visibility; reduces the risk of infection by reducing intrarenal pressure. However, in some cases, the acute ureteric injury may occur during ureteroscopic access sheath (UAS) placement.

Inclusion Criteria:

• Upper ureteric stone or stone kidney (with stone burden equal to or less than 20mm).
• 2. Non stented.
• Age (Above 18 years old).

Exclusion Criteria:

• Acute or chronic renal insufficiency.
• Uncorrected coagulopathy.
• Previous open (lumber or ureteric) surgery.
• Active urinary tract infection unless treated.

The study will be available under a reasonable request from the corresponding author.

One year after the end of the study.