Kidney stones measuring 20 mm or less are commonly managed using minimally invasive surgical techniques. Two widely used approaches are Super-mini Percutaneous Nephrolithotomy (SMP) and Flexible Ureteroscopy (fURS). Although both techniques are considered effective and safe, they differ in surgical approach, use of disposable equipment, postoperative recovery, and treatment cost. In resource-limited settings, economic considerations may play an important role in treatment selection.

This single-center randomized controlled trial was conducted at Bach Mai Hospital, Hanoi, Vietnam, to compare clinical outcomes, safety, and direct medical costs of SMP versus fURS in patients with renal stones ≤20 mm. Eligible patients were randomly assigned in a 1:1 ratio to undergo either SMP or fURS.

The primary outcome was the stone-free rate assessed by postoperative imaging. Secondary outcomes included operative time, postoperative complications, length of hospital stay, hemoglobin drop, and total direct treatment cost per case. The results of this study aim to provide evidence to support clinical decision-making for the management of renal stones, particularly in healthcare settings with limited resources.

Inclusion Criteria:

• Adult patients (≥18 years of age).
• Patients with renal stones measuring ≤20 mm in maximal diameter on preoperative imaging.
• No prior surgical or interventional procedure during the same hospital admission.
• Ability and willingness to provide written informed consent.

Exclusion Criteria:

• Pregnancy.
• Coagulation disorders or bleeding diathesis contraindicating surgery.
• Contraindications to either Super-mini Percutaneous Nephrolithotomy (SMP) or Flexible Ureteroscopy (fURS).
• Patients undergoing SMP or fURS for ureteral stones that migrated back into the kidney.