The investigators aim at this study to prospectively assess procedure-related outcomes after RIRS for renal calculi less than 20 mm, including stone free rate (SFR), predictors of successful outcome, complications types/rate, readmission rate and the need of auxiliary procedures. In addition, patient-reported outcomes after this modality of intervention are going to be assessed.

Inclusion Criteria:

1. Ability to give informed consent.

2. Stone criteria:

   • Less than 20 mm.
   • Infectious stone.
   • Growing stone on follow-up.

3. Kidney criteria:

   • Obstructing stone causing hydronephrosis.
   • Solitary kidney or bilateral renal stones.

4. Patients criteria:

   • Age ≥18 years.
   • Symptomatic stone causing pain or hematuria.
   • Patient comorbidity omitting other modalities as bleeding diathesis or skeletal deformities.
   • Patient preference or patients' social situation concerning profession or amount of travel

Exclusion Criteria:

1. Inability to give informed consent.

2. Stone criteria:

   • More than 20 mm.
   • Peripheral calyceal asymptomatic stone static in size on follow-up.
   • Unsuitable/failure of initial treatment modalities (oral dissolution therapy-SWL) for stones less than 20 mm.