Are we ready to predict percutaneous nephrolithotomy (PCNL) stone-free failure?

Abstract

To develop a tool, both simple and reliable, for postoperative percutaneous nephrolithotomy (PCNL) stone-free failure prediction. Materials and methods: We analysed a sample of 116 patients, who underwent conventional PCNL from 2011 to 2014. Cases with residual stones ⩽ 4 mm in size were regarded as clinically insignificant and 'stone-free'. Results: According to the low-dose computed tomography (CT) scan performed within 24 hours after operation, the patients were stratified as follows: 72 stone-free and 44 with residual stones. Among the analysed variables, three were derived as most important for prediction purposes: an additional stone in a calyx with an acute angle (⩽ 45°), represented by 'A'; an additional stone in a long calyx (⩾ 10 mm) with a narrow infundibulum (⩽ 8mm), represented by 'C'; and a stone size that is > 24 mm, represented by 'S'. These were abbreviated as the 'ACS' score. Depending on the absence or presence of each of these three variables, a score of 0 or 1 was assigned. If the ACS score is 0, then the probability of being a stone-free patient was about 88%; however, when the ACS score is 3, then the probability of being stone free was just 8%. Conclusion: Use of the ACS score seemed to be a simple and reliable tool for PCNL stone-free failure prediction.

How practical is the application of percutaneous nephrolithotomy scoring systems? Prospective study comparing Guy’s Stone Score, S.T.O.N.E. score and the Clinical Research Office of the Endourological Society (CROES) nomogram

“…Many factors have been identified to predict clearance rates after PCNL such as stone burden, composition, number and location, HU, BMI, skin-to-stone distance (SSD), abnormal renal anatomy etc. However, a significant predictor alone is not a predictive tool in itself and thus various models have been developed by various authors combining various such parameters [9] , [10] , [11] , [15] , [16] , [17] , [18] . A few of such models include the GSS [9] , Staghorn Morphometry [16] , Seoul National University Renal Stone Complexity Scoring system [15] , S.T.O.N.E.…”

“…A few of such models include the GSS [9] , Staghorn Morphometry [16] , Seoul National University Renal Stone Complexity Scoring system [15] , S.T.O.N.E. Nephrolithometry score [10] , CROES Nephrolithomteric Nomogram [11] , and recently developed acute angle, complicated calyx and stone size (ACS) score [18] . A logistic regression model was also developed by Zhu et al [19] for minimally invasive PCNL but it might not apply to standard PCNL.…”

Methylene blue-guided retroperitoneoscopy technique: alternative for percutaneous nephrolithotomy in cases with renal access failure

“…Furthermore, having to receive anesthesia for the second time for the operation and related psychological effects result in a very difficult process for the patient. If possible, completing the operation in a single session is more appropriate to avoid these unfavorable situations (16,17).…”