Lower pole kidney stones have been associated with poor shock wave lithotripsy (SWL) outcomes due to its location. However, the real impact of collecting system anatomy on stone clearance after SWL is uncertain. There is a lack of prospective well-controlled studies to determine if lower pole kidney stones have inferior outcomes compared to non-lower pole kidney stones when treated with SWL.
We prospectively evaluated patients with a single kidney stone of 5 to 15 mm undergoing SWL from Jun-12 through Jan-19. All patients were submitted to computed tomography before and 3 months after the procedure. Demographic data (age, gender, BMI), stone features (stone size, stone area, stone density, and stone-skin distance – SSD), and collecting system anatomy (infundibular length and width, and infundibulopelvic angle) were recorded. Outcomes (fragmentation and stone clearance rates) were compared between lower pole and non-lower pole cases. Then, a multivariate analysis including all variables was performed to determinate which parameters significantly impact on SWL outcomes.
One hundred and twenty patients were included in the study. Mean stone size was 8.3 mm and mean stone density was 805 HU. Overall stone fragmentation, success, and stone-free rates were 84.1%, 64.1%, and 34.1%, respectively. There were no significant differences in stone fragmentation (76.0% vs. 71.4%; p=0.624), success rate (57.6% vs. 53.3%; p=0.435), and stone-free rate (40.2% vs. 35.7%; p=0.422) in the lower versus non-lower pole groups, respectively. On multivariate, only stone density (p<0.001) and SSD (p=0.006) significantly influenced fragmentation. Stone size (p=0.029), stone density (p=0.002), and SSD (p=0.049) significantly influenced kidney stone clearance.
Stone size, stone density, and SSD impact on SWL outcomes. Lower pole kidney stones have similar fragmentation and stone clearance compared to non-lower pole kidney stones.
Journal of endourology. 2019 Oct 09 [Epub ahead of print]
Fabio Cesar Miranda Torricelli, Manoj Monga, Fernando Yamauchi, Giovanni Scala Marchini, Alexandre Danilovic, Fabio Carvalho Vicentini, Carlos Batagello, Miguel Srougi, William Carlos Nahas, Eduardo Mazzucchi
Cleveland Clinic, Urology, 9500 Euclid Avenue / Q10, Cleveland, Ohio, United States, 44195; ., Cleveland Clinic, Urology, Cleveand, Ohio, United States; ., Sao Paulo, Brazil; ., Hospital das Clínicas, University of Sao Paulo Medical School, Section of Endourology, Division of Urology, São Paulo, São Paulo, Brazil; ., University of Sao Paulo Medical School, Sao Paulo, Brazil, Section of Endourology, Division of Urology São Paulo, Av. Dr. Eneas de Carvalho Aguiar, 255, 7 and. Sala 7175, São Paulo, São Paulo, Brazil, 05403-000; ., university of sao paulo medical school, Urology, R. Dr. Eneas de Carvalho Aguiar 255, 7th Floor, sao paulo, Brazil, 05400000; ., Sao Paulo, Brazil; ., Sao Paulo, Brazil; ., University of Sao Paulo, 28133, Av Dr Eneas Aguiar 256, Sao Paulo, Brazil, 05508-900; ., Hospital das Clínicas, University of Sao Paulo Medical School, Division of Urology, barata ribeiro street,490 room25, São Paulo, São Paulo, Brazil, 01308001; .