Should the RIRS Score Be Calculated Before Every RIRS Procedure?
Yes, calculating a validated RIRS scoring system before every retrograde intrarenal surgery procedure is strongly recommended to predict stone-free rates and guide surgical planning.
Rationale for Preoperative Scoring
The R.I.R.S. scoring system was specifically developed to preoperatively estimate stone-free rates after RIRS and has demonstrated excellent predictive accuracy with an area under the receiver operating characteristic curve of 0.904 1. This scoring system evaluates four reproducible factors based on preoperative CT urography: renal stone density, inferior pole stone presence, renal infundibular length, and stone burden 1.
- The R.I.R.S. score ranges from 4 to 10 points and shows significant correlation with stone-free status (p < 0.001) 1
- The modified Seoul National University Renal Stone Complexity (S-ReSC) score also demonstrates superior predictive accuracy (AUC 0.806) compared to other scoring systems like the RUS score (AUC 0.692, p = 0.012) 2
- Stone-free rates decrease significantly based on score stratification: low scores (1-2) achieve 94.2% success, medium scores (2-4) achieve 84.0%, and high scores (>4) achieve only 45.5% success 2
Clinical Applications of Preoperative Scoring
Calculating these scores enables critical preoperative decision-making:
- Surgical planning and patient counseling: The scoring system allows realistic expectation-setting with patients regarding success rates, with overall stone-free rates after RIRS ranging from 61.5% on postoperative day 1 to 73.6% at one month 1
- Treatment modality selection: Scores can help determine whether RIRS is the optimal first-line approach or if alternative treatments (percutaneous nephrolithotomy) should be considered, particularly for high-complexity stones 2, 1
- Resource allocation: Preoperative scoring facilitates appropriate surgical scheduling and comparison of outcomes between centers and within centers over time 1
Critical Considerations
RIRS as second-line therapy has significantly lower success rates (67%) compared to first-line therapy (80%, p < 0.05) 3. This finding emphasizes the importance of preoperative scoring to identify patients who may have already failed other modalities and require modified expectations or alternative approaches 3.
- Patients with solitary kidneys can safely undergo RIRS with comparable stone-free rates (82.8% vs 83.6%) and complication rates to those with bilateral kidneys 4
- RIRS has no specific contraindications except active urinary tract infection and can be performed even in patients with coagulopathies 5
Practical Implementation
Before every RIRS procedure, obtain preoperative CT urography and calculate either the R.I.R.S. score or modified S-ReSC score 2, 1. These measurements are reproducible and based on objective imaging parameters rather than subjective assessment 1.
The scoring should inform:
- Patient selection and counseling about realistic success rates
- Surgical technique modifications for complex cases
- Decision to proceed with RIRS versus alternative approaches for high-score (high-complexity) cases where success rates drop below 50% 2