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The objectives of this study are to assess the efficacy and safety of retrograde ureteroscopic holmium laser lithotripsy for intrarenal calculi greater than 2 cm in diameter. A total of 24 patients with a stone burden >2 cm were treated with retrograde ureteroscopic laser lithotripsy. Primary study endpoints were number of treatments until the patient was stone free and perioperative complications with a follow-up of at least 3 months after intervention. In 24 patients (11 women and 13 men, 20-78 years of age), a total of 40 intrarenal calculi were treated with retrograde endoscopic procedures. At the time of the initial procedure, calculi had an average total linear diameter of 29.75 ± 1.57 mm and an average stone volume of 739.52 ± 82.12 mm(3). The mean number of procedures per patient was 1.7 ± 0.8 (range 1-3 procedures). The overall stone-free rate was 92%. After 1, 2 and 3 procedures 54, 79 and 92% of patients were stone free, respectively. There were no major complications. Minor postoperative complications included pyelonephritis in three cases (7.5%), of whom all responded immediately to parenteral antibiotics. In one patient the development of steinstrasse in the distal ureter required ureteroscopic fragment disruption and basketing. Ureteroscopy with holmium laser lithotripsy represents an efficient treatment option and allows the treatment of large intrarenal calculi of all compositions and throughout the whole collecting system even for patients with a stone burden of more than 2 cm size.

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This study aims to evaluate whether optical coherence tomography (OCT) using both the surface and the endoluminal technique is feasible to investigate the locations and degree of encrustation process in clinically used ureteral stents. After removal from patients, 14 polyurethane JJ stents were investigated. A fresh JJ served as a control. The external surfaces were examined using an endoscopic surface OCT whereas the intraluminal surfaces were investigated by an endoluminal radial OCT device. The focus was on detection of encrustation or crystalline sedimentation. In 12 female and two male patients, the median indwelling time of the ureteral catheter was 100 days (range, 19-217). Using the endoluminal OCT, the size and grade of intraluminal encrustation could be expressed as a percentage relating to the open lumen of the reference stent. The maximum encrustation observed resulted in a remaining unrestricted lumen of 15-35 % compared to the reference. The luminal reduction caused by encrustation was significantly higher at the proximal end of the ureteral stent as compared to its distal part. The extraluminal OCT investigations facilitated the characterization of extraluminal encrustation. OCT techniques were feasible and facilitated the detection of encrustation of double pigtail catheters on both the extra and intra luminal surface. Quantitative expression of the degree of intraluminal encrustation could be achieved, with the most dense and thickened occurrence of intraluminal incrustation in the upper curl of the JJ stent.

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