Pelvicalyceal anatomy and stone related factors as predictors of stone free rate in retrograde intrarenal surgery for lower calyceal stone.

Introduction: The objective of the present study is to evaluate the various pelvi-calyceal anatomy related and stone related parameters and their influence on stone free rate in retrograde intrarenal surgery for lower calyceal stones.

Methods: The retrospective analysis of records of 206 patients who underwent retrograde intrarenal surgery for lower calyceal stones from December 2021 and November 2023.The patients were divided into two groups: stone free group and residual stone group. Various factors like patients' characteristics, stone size, volume, numbers, density, infundibular width, infundibulopelvic angle, operative time, lasing time, type of laser, and retreatment rate were compared between two groups.

Results: The mean stone size in stone free group was 1.1 ± 0.7 cm whereas in residual stones group was 1.7 ± 0.4 cm (p = 0.03). Overall stone free rate was 62.1% (128/206) whereas residual stone rate was 37.9% (78/206). In stone-free group only 2.3% (3/128) of the patients had an acute infundibulopelvic angle ⩽ 30° whereas in the residual stones group an acute infundibulopelvic angle ⩽ 30° was found in 58.9% (46/78) of the patients (p < 0.001). Patients with an infundibulopelvic angle ⩽ 30°, 93.8% (46/49) had residual stones, whereas infundibulopelvic angle > 30° only 20.1% (32/157) had residual stones (p < 0.001). Multivariate logistic regression analysis has demonstrated that Infundibulopelvic angle and stone size were the only significant factors in predicting stone free rate for lower calyceal stone.

Conclusion: Infundibulopelvic angle and stone size have significant impact on the stone free rates in retrograde intrarenal surgery for lower calyceal stones.