What are the indications for Retrograde Intrarenal Surgery (RIRS)?

Indications for Retrograde Intrarenal Surgery (RIRS)

RIRS is indicated as primary treatment for renal stones <2 cm, and is increasingly favored for upper ureteral stones where extracorporeal shock wave lithotripsy (ESWL) has failed or is not feasible. 1

Primary Indications

Stone Size and Location

• Renal stones <2 cm: RIRS is recommended as the main surgical modality, particularly when ESWL is not feasible or desirable 2, 3
• Upper ureteral stones: Flexible ureteroscopy (which includes RIRS) is increasingly favored due to technical advances, especially for stones where retrograde access is challenging 1
• Lower pole renal stones: RIRS has evolved from being merely an adjunct for lower calyx stones unresponsive to ESWL to a primary treatment option 2
• Large stones (1.6-3.5 cm): RIRS can be considered as a viable alternative to percutaneous nephrolithotomy (PCNL), though multiple sessions may be required 4

Failed Prior Treatment

• Post-ESWL failures: RIRS is the best option for managing stones that have failed extracorporeal shock wave lithotripsy 4
• Post-PCNL residual calculi: RIRS effectively treats residual fragments after percutaneous procedures 4
• Steinstrasse: Can be managed with RIRS when stone fragments obstruct the ureter after ESWL 1

Special Clinical Scenarios

Anatomical Considerations

• Infundibular stenosis: RIRS is indicated when narrow infundibula prevent stone passage or limit ESWL effectiveness 3, 5
• Renoureteral malformations: Anatomical abnormalities that complicate other approaches make RIRS preferable 3
• Musculoskeletal deformities: Patients with skeletal abnormalities that prevent positioning for PCNL or ESWL 3, 5
• Urinary diversion: Percutaneous antegrade ureteroscopy (which uses similar retrograde principles) is indicated for ureteral stones after urinary diversion 1

Patient-Specific Factors

• Bleeding diathesis/coagulopathies: RIRS has no specific contraindications for patients with various coagulopathies, unlike PCNL which requires careful anticoagulant monitoring 2, 3
• Obesity: RIRS is particularly advantageous in obese patients where PCNL positioning and access are challenging 3, 5
• Pregnancy: While not explicitly stated for RIRS, flexible ureteroscopy is recommended when antithrombotic therapy cannot be stopped 1

Combined Procedures

• Large impacted proximal ureteral stones (>15 mm) in dilated systems: Percutaneous antegrade ureteroscopy is an option when retrograde access is not feasible 1
• Renal stone removal with concurrent ureteral stones: RIRS can address both pathologies in a single session 1

Contraindications

The only absolute contraindication to RIRS is active urinary tract infection (UTI). 2

• Untreated UTI: Must be treated before proceeding with RIRS 1, 2
• General anesthesia risks: Standard perioperative assessment applies, though not specific to RIRS 1

Comparative Advantages Over Other Modalities

Versus PCNL

• Lower complication rates: RIRS demonstrates less morbidity, particularly reduced bleeding risk and transfusion requirements 6, 4
• Shorter hospital stay: Typically 24 hours versus longer stays with PCNL 4
• Faster recovery: Patients can resume normal activities within 2 days 4
• Similar stone-free rates for stones <2 cm: RIRS achieves 86.6% clearance in first sitting, 100% with second session 4

Versus ESWL

• Better for lower pole stones: RIRS overcomes the gravitational disadvantage of ESWL for dependent calyceal stones 2
• Single-session treatment: Avoids multiple ESWL sessions and associated complications like steinstrasse 1
• Direct visualization: Allows complete stone clearance under direct vision 3

Important Caveats

• "Dust and go" approach: Should be limited to large renal stones; complete stone removal remains the goal 1
• Stone size >2 cm: While feasible, may require multiple sessions and should be weighed against PCNL, which remains the standard for large stones 1, 6
• Prestenting consideration: May improve treatment outcomes for renal stones, though not routinely required 1
• Pediatric patients: RIRS efficiency has been proven in children, with technique modifications for smaller anatomy 3