Presentation Authors: Nuno Morais*, Braga, Portugal, Carla Ribeiro, Paulo Mota, Braga , Portugal, João Torres, Sara Anacleto, Ricardo Rodrigues, Braga, Portugal, Emanuel Carvalho-Dias, Braga , Portugal, Carlos Oliveira, Mário Cerqueira, Estêvão Lima, Braga, Portugal
Introduction: The advent of minimally invasive surgical techniques has enabled the reduction of morbidity associated with surgical treatment of renal lithiasis. However, there is not a consensus on the best approach to residual stones, as it is known that these fragments have the potential to cause complications after elective procedures.The objective of this study is to evaluate the characteristics and the natural history of residual stones after percutaneous nephrolithotomy (PCNL) or flexible ureterorenoscopy (F-URS) for treatment of kidney calculi.
Methods: Retrospective analysis of 369 patients submitted to endoscopic procedures for treatment of kidney stones. The presence and characteristics of residual fragments was accessed with follow-up radiologic exams and the occurrence of complications or the necessity of additional procedures were evaluated.
Results: The overall stone-free rate was 56.6% in F-URS and 60.9% in PCNL. The natural history of 239 patients with residual fragments was the spontaneous passage in 10.8% (26) of cases, 29.7% (71) developed new symptoms, 31.3% (75) had complications and 38.5% (92) required a new surgical procedure. The residual stones larger than 4mm had more complications (p < 0.001), more recurrence of symptoms (p=0.02) and more additional surgeries (p < 0.001) than stones smaller than 4mm. However, there was not found a significant association in spontaneous passage of residual calculi and its size ( < 4mm vs >4mm; p=0.305). In the logistic regression models, the size of the residual fragments and the multi-calicial distribution were predictors of the development of new symptoms (p=0,005 and p=0.016, respectively) and the need of surgical re-intervention (p < 0.001 and p=0.028, respectively). For each millimetre increase in size of the residual stone the chance of having a renal colic caused by a residual fragment increased by 8.7%. The location in the upper calyx, the multi-calicial distribution and the size of residual fragments were predictors of complications (p=0.034, p=0.033 and p < 0.001, respectively).
Conclusions: Residual stones are a common scenario after endoscopic renal lithiasis procedures and have the potential to cause morbidity and complications, even in the case of small stones with < 4mm of diameter. More studies with prospective and randomized design are necessary to confirm these findings.