Pole Calculi Research Articles

Micro-percutaneous nephrolithotomy (micro-PNL) vs retrograde intra-renal surgery (RIRS): dealer's choice? The devil is in the details

Advances in minimally invasive endourological techniques continue to provide the Urologist a myriad of options for the management of symptomatic renal calculi. Previously, shock wave lithotripsy (SWL) or standard percutaneous nephrolithotomy (PNL) were the only two endourological options available. Yet, limitations of these two ‘standard’ techniques result from hard or dependent stones (for SWL) or the potential of increased morbidity during the treatment of small renal calculi (for PNL). Now the introduction of smaller fibre-optic needle-scopes combined with laser stone fragmentation (micro-PNL or ‘microperc’) provides access to difficult-to-reach renal calculi with minimal patient morbidity. Moreover, newer flexible ureteroscopes, along with nitinol baskets and graspers (retrograde intra-renal surgery or ‘RIRS’) allow another minimally invasive option for hard-to-reach renal calculi. In the present issue of BJUI, Sabnis et al. 1 present a well performed, randomised, prospective trial comparing microperc to RIRS for the management of renal calculi of <1.5 cm in diameter. They determined that both procedures were essentially identical in their ability to remove small-to-moderate sized renal stones with minimal patient morbidity/complications. Yet, both of these procedures have inherent limitations that are unique to the instrumentation used for each technique. Microperc has limited applicability for stones located anteriorly within the kidney, while RIRS is an ideal technique to access symptomatic renal stones within an anterior calyx 2. RIRS may not be able to target lower pole calculi in those patients with an acute infundibular angle or stones in a calyceal diverticulum, whereas a microperc can be used to reach hard-to-access calculi 3. One must accept that both of these innovative procedures are inefficient in their ability for removal of large volume stones and neither technique offers an efficient method of clearing multiple stone fragments. Ideally, both microperc and RIRS should only be used for small volume renal calculi. I would offer that both procedures are safe and effective alternatives for the management of small renal calculi. Yet, we must be realistic in offering these techniques to our patients, pairing each procedure with the most appropriate situation. Even in 2013, large volume renal calculi are best managed by standard or mini-PNL, where devices such as ultrasonic lithotripsy or dual ultrasonic/pneumatic lithotripsy offer efficient methods of stone removal 4. SWL is still a reasonable option for the treatment of renal calculi of ≤1 cm in diameter. Now RIRS and microperc can be added to the list of treatment options for managing symptomatic renal calculi. In patients with large renal calculi, along with multiple medical comorbidities or bleeding diatheses/on anti-coagulation, RIRS provides another, yet inefficient, alternative for stone removal, often requiring multiple procedures to clear the stone. In those situations where the flexible ureteroscope cannot target a renal calculus of <1.5 cm, microperc provides the option of accessing the calculus, yet offers no method of efficiently clearing stone fragments. If we set reasonable expectations for the use of these two minimally invasive endourological techniques, our patients will surely benefit. None declared.

Focused Ultrasound to Expel Calculi from the Kidney: Safety and Efficacy of a Clinical Prototype Device

Focused ultrasound has the potential to expel small stones or residual stone fragments from the kidney, or move obstructing stones to a nonobstructing location. We evaluated the efficacy and safety of ultrasonic propulsion in a live porcine model. Calcium oxalate monohydrate kidney stones and laboratory model stones (2 to 8 mm) were ureteroscopically implanted in the renal pelvicalyceal system of 12 kidneys in a total of 8 domestic swine. Transcutaneous ultrasonic propulsion was performed using an HDI C5-2 imaging transducer (ATL/Philips, Bothell, Washington) and the Verasonics® diagnostic ultrasound platform. Successful stone relocation was defined as stone movement from the calyx to the renal pelvis, ureteropelvic junction or proximal ureter. Efficacy and procedure time was determined. Three blinded experts evaluated histological injury to the kidney in the control, sham treatment and treatment arms. All 26 stones were observed to move during treatment and 17 (65%) were relocated successfully to the renal pelvis (3), ureteropelvic junction (2) or ureter (12). Average ± SD successful procedure time was 14 ± 8 minutes and a mean of 23 ± 16 ultrasound bursts, each about 1 second in duration, were required. There was no evidence of gross or histological injury to the renal parenchyma in kidneys exposed to 20 bursts (1 second in duration at 33-second intervals) at the same output (2,400 W/cm(2)) used to push stones. Noninvasive transcutaneous ultrasonic propulsion is a safe, effective and time efficient means to relocate calyceal stones to the renal pelvis, ureteropelvic junction or ureter. This technology holds promise as a useful adjunct to surgical management for renal calculi.

1539 TUBELESS PERCUTANEOUS NEPHROLITHOTOMY FOR COMPLEX RENAL CALCULI AND COMPLICATED PROCEDURES

INTRODUCTION AND OBJECTIVES: Tubeless PCNL is underutilized, usually as an option in nonbleeding, uncomplicated monotracts with complete stone clearance & decided intraoperatively. In this study we evaluated its feasibility, safety and efficacy in a tertiary teaching institute. METHODS: Forty (40) patients were alternately randomized (1:1) into tube (T) and tubeless (TL) PCNL groups. Tract dilatations were done using Alken metal dilators, no sealant or electrocautery was used for hemostasis and a 6 Fr JJ stent was kept. In T group 24 Fr nephrostomy tubes were placed. In TL group JJ stent was removed at 48 hours after operation and in tube group it was removed 1 week after drying of nephrostomy site. In TL group deep skin stitched were applied. Analgesic (intravenous tramadol) requirement and Visual Analogue Scores (noted every 3 hours) were recorded in first 48 hours (hrs). Postoperative X-ray KUB (on Day1) and ultrasound scans (on postoperative days 1, 2, 3 and 3 weeks) were done in all to see stone clearance and perinephric/puncture tract/intrarenal collection or hematoma. RESULTS: Demographic data and outcomes are shown in table 1. One procedure in TL required conversion to tube because of intraoperatively diagnosed pleural violation. Despite complicated calculi (55%) and high risk situations (50%), none in TL group had any significant perinephric collection or severe postoperative bleeding requiring any intervention. Patient age, size and type of stones, punctures, stone clearance rate, hematuria clearance time, mean haemoglobin drop, transfusion requirements, and complication rate were similar in both groups. TL-PCNL is superior (p values 0.05) to T-PCNL in terms of VAS pain scores and analgesic requirement in first 48 hrs, leak from tract site and hospital stay. CONCLUSIONS: In TL PCNL, deep skin stitches with JJ stenting for 48 hrs ensure a good local bleeding control and a dry tract site. TL-PCNL may be considered a new standard for PCNL. Nephrostomy should only be used for specific purposes like intraoperative pleural violation, major pelvicalyceal injury, balloon tamponading or relook. Parameter Tube group Tubeless group Number of patients(Right/left side) 20(13/7) 20(11/9) Age in years(mean/range) 33.2(15-55) 36.7(17-52) Sex(M:F) 2.3:1 3:1 Stone burden(maximum diameter in cms) (mean/range) 2.72(1.8-3.8) 2.56(1.9-4.2) No. of patients with Simple Calculi(Pelvis/ Calyceal) 8(6/2) 9(7/2) No. of patients with Complex Calculi(Multiple pole calculi/ Staghorns) 12(7/5) 11(7/4) No.of punctures(mean/range) 1.4(1-3) 1.3(1-3) Tracts: single/multiple(No.of pts.) 14/6 15/5 High risk situations : Infundibular tear/ Extravasation & tract loss/ Obvious bleeding/ Stone guided punctures (No.of pts.) 2/1/4/1 2/1/5/2 Operative time in minutes (mean/range) 106(60-170) 108(80-130) Hemoglobin drop in gm/dl (mean/range) 1.36(0-4.1) 1.21(0-3.1) VAS score in 0-24 hrs & 25-48 hrs(mean/range) 3.5(2.1-4.6) & 2.5(1-3.5) 2.4(0-3.8) & 1.9(0.5-2.5) Analgesic (tramadol in mg)requirement in 0-48 hrs (mean/range) 165(100-250) 85(50-100) Hematuria settling time in hrs(mean/range) 29.1(6-192) 36(3-160) Nephrostomy removal time in hrs(mean/range) 42.6(30-72) Not applicable(NA) Tract site leak duration in hrs(mean/range) 13.8(0-72) 0 Hospital stay in hrs(mean/range) 121.4(50-168) 88.3(52-210) Blood transfusion(No.of pts.) 4 3 Complications:Hydro-pneumothorax/ UTI/Late hematuria(No.of pts.) 1/3/0 1/2/1 Complete stone clearance rate : after first procedure/ after relook/ At 3 weeks follow up(in %) 70/80/90 70/NA/85

Natural History of Asymptomatic Renal Stones and Prediction of Stone Related Events

The appropriate management for asymptomatic renal stones remains unclear. We assessed the natural history and progression rate of such stones and identified clinical factors associated with an increased risk of stone related events. We retrospectively reviewed the medical records of 201 male and 146 female patients with asymptomatic renal stones. It was recommended that patients be followed every 6 months. Mean followup was 31 months (range 6 to 180). Patients were divided into 2 groups by stone related events, including spontaneous stone passage, flank pain, stone growth or the need for intervention during followup. Spontaneous passage occurred in 101 patients (29.1%). Of the patients 186 (53.6%) and 161 (46.4%) did and did not have stone related events, respectively. Of the whole cohort 85 patients (24.5%) required intervention but only 4.6% needed surgery. At 19 months after diagnosis 50% of the patients had a symptom. Those with stone related events were more likely to be younger (mean ± SD age 46.6 ± 12.7 vs 49.3 ± 12.6 years) and male, and have a stone history (p = 0.047, 0.017 and 0.014, respectively). Male gender significantly decreased the probability of freedom from stone related events (log rank test p = 0.0135) and it was an independent predictor of stone related events (HR 1.521, p = 0.009). Younger patients, and those with smaller stones and no stone growth were more likely to experience spontaneous passage and less likely to undergo intervention (each p <0.05). Asymptomatic renal stones can be followed safely but long-term followup is necessary. Periodic followup and early intervention should be recommended in patients with risk factors.

CT Imaging: Radiation Risk Reduction—Real-Life Experience in a Metropolitan Outpatient Imaging Network

The exponential growth of CT imaging has been fueled by recent technical advances, improved diagnostic accuracy, and medicolegal pressures. CT imaging has replaced many more invasive and expensive tests and has proven itself an indispensable part of diagnostic medicine. This growth in CT imaging, however, has also been accompanied by an unavoidable increased cumulative radiation exposure to the general public. It is important to fully understand the risks and benefits of and alternatives to CT imaging so that an informed decision can be made. A number of simple strategies may be used to minimize radiation exposure during CT imaging. These include protocol redesign and CT dose adjustments on the basis of each patient's body mass index, limiting length of coverage and multiphase examinations, and iterative reconstruction. At Imaging Healthcare Specialists, a highly successful program of radiation dose reduction was created, and dose savings of up to 90% have been achieved in select patients while maintaining diagnostic image quality. The approach is simple, reproducible, and inexpensive.

Flexible ureterorenoscopy (URS) for lower pole calculi

Flexible ureterorenoscopy (URS) for lower pole calculi

Research on the Completeness of Minimum Zone Method of Straightness Error in Plane

In the national standard,GB/T 11336-2004,the results of some groups of datas processed on the pole calculus method for minimum tolerance zone evaluation of the straightness error in a plane are against the principal of minimum tolerance zone method,i.e.high-low-high or low-high-low,that means the pole calculus method exists some incompleteness.To solve this problem,the evaluation method of pole searching in certain direction and iteration is proposed.Theoretical analysis and the processing results of straightness error in a plane have proved that the method of pole searching in certain direction and iteration coincides well with the minimum tolerance zone principal in the straightness error evaluation,i.e.high-low-high or low-high-low.The processing results of data also show that the new method has good completeness and reliable precise evaluating results and the evaluating process of the new method is more efficient and absolutely convergent.Particularly,the new method can overcome the defects of the pole calculation method of the straightness error in a plane existed in the national standard,GB/T 11336-2004.

E44 A retrospective study of comparing minimally invasive percutaneous nephrolithotomy and flexible ureteroscopy for lower pole calculi more than 1 cm in diameter

E44 A retrospective study of comparing minimally invasive percutaneous nephrolithotomy and flexible ureteroscopy for lower pole calculi more than 1 cm in diameter

Is the gravity effect of radiographic anatomic features enough to justify stone clearance or fragments retention following extracorporeal shock wave lithotripsy (SWL)

We determined whether the gravity effect of radiographic anatomic features on the preoperative urography (IVP) are enough to predict fragments clearance after shock wave lithotripsy (SWL). A Total of 282 patients with mean age 45.8 ± 13.2 years (189 male, 93 female), who underwent SWL due to renal calculi between October 2005 and August 2009 were enrolled. The mean calculi load was 155.72 ± 127.66 mm². The patients were stratified into three groups: patients with pelvis calculi (group 1); patients with upper or middle pole calculi (group 2) and patients with lower pole calculi (group 3). Three angles on the pretreatment IVP were measured: the inner angle between the axis of the lower pole infundibular and ureteropelvic axis (angle I); the inner angle between the lower pole infundibular axis and main axis of pelvis-ureteropelvic (UP) junction point (angle II) and the inner angle between the lower pole infundibular axis and perpendicular line (angle III). Multivariate analysis was used to define the significant predictors of stone clearance. The overall success rate was 85.81%. All angles, sessions number, shock waves number and stone burden were significant predictors of success in patients in group 1. However, in group 2 only angle II and in group 3 angles I and II had significant effect on stone clearance. Radiographic anatomic features have significant role in determining the stone-free rate following satisfactory fragmentation of renal stones with SWL. The measurement of infundibulopelvic angle in different manner helps to predict the stone-free status in patients with renal calculi located not only in lower pole, but also in renal pelvis and upper or middle pole. Gravity effect is not enough to justify the significant influence of the radiographic anatomic features on the stone clearance and fragments retention after SWL.

Gibt es den symptomlosen Nierenstein?

Asymptomatic renal calculi without any history of colic, hematuria or infection can be found as an incidental finding during preven-tive check-ups. The aim of our study was to eval-uate whether these stones provoke symptoms with the need for further treatment during the follow-up and whether they cause cortical defects which may consecutively affect the renal func-tion. In a prospective study we evaluated 104 patients with renal calculi. The -medical history, radiological findings and functional imaging as well as urine and blood analyses were recorded and evaluated. The influence of stone size and localisation on the development of acute stone-related symptoms, renal function and renal scarring were evaluated. Furthermore, we analysed whether localised pathological findings in radiographic or functional imaging may influence the creatinine level. The follow-up was be-tween 12 and 48 months (median: 25 months). During the study period 27 / 104 of our patients (26 %) developed symptomatic events (renal colic, hematuria, infection) in which patients with middle pole calculi with a mean -cumulative stone diameter of 9.8 mm had the -highest risk. A localised renal scarring could be found in 36.6 %. These patients had a significantly higher risk in presenting an increased creatinine level. Increasing stone size was diagnosed in 39 cases (37.5 %). Asymptomatic renal stones have to be controlled regularly in order to prevent the -patient from loss of renal function and hypertension caused by increasing stones or urinary tract infection.

The difficult ureter: what is the incidence of pre-stenting?

Difficulty may be encountered with retrograde access for rigid and flexible ureterorenoscopy (URS) due to anatomic abnormalities, a narrow ureteric lumen, tortuous ureteric path or previous instrumentation. Ureteric dilatation using a balloon or tapered dilator can occasionally fail and will usually lead to the placement of a ureteric stent. We present our experience and incidence of pre-stenting after failed standard access and dilatation techniques, the aim being to quote a figure for the patient at the time of consent. Data were collected prospectively from a single surgeon at a regional tertiary referral stone unit. The outcomes of those patients pre-stented, for failed access, were recorded. Between December 2007 and December 2008, a total of 119 patients underwent flexible and rigid URS. Mean patient age was 49 years (range, 19-86 years). Of these, 107 cases were undertaken for urolithiasis and 12 cases for diagnosis of upper tract malignancy. 12% (13/107) of cases were for pain and non-diagnostic imaging and 8.4% (9/107) of patients were pre-stented because of failed access, without complication, and subsequently had successful interval treatment. Of the remaining successful cases of confirmed urolithiasis, 33% (28/85) and 67% (56/85) were undertaken for ureteric and renal calculi, respectively. Stone clearance rates were 83% (19/23) and 75% (3/4) for lower pole renal calculi 5-10 mm and > 10 mm in size, respectively. The overall clearance rate for lower pole calculi was 81% (22/27). The ureteric stone clearance rate was 86% (24/28) rising to 92% (24/26) in those solitary stones less than 10 mm in size. The incidence of ureteric pre-stenting in a tertiary referral unit was 8% and should be considered and indeed discussed with patients when obtaining pre-operative consent, especially for purely elective, non-urgent, upper tract cases. The alternative for these difficult, tight ureters is extensive balloon dilatation, with the risk of trauma and the potential for long-term stricture formation.

Arguments for a comprehensive metabolic evaluation of the firsttime stone former

Arguments for a comprehensive metabolic evaluation of the firsttime stone former

A Prospective, Randomized Trial of Management for Asymptomatic Lower Pole Calculi

We determined the natural course and compared the deleterious effects in kidneys of shock wave lithotripsy, percutaneous nephrolithotomy and observation for asymptomatic lower caliceal stones. Between April 2007 and August 2008 patients with asymptomatic lower caliceal calculi were enrolled in the study. To assess stone status noncontrast abdominal helical computerized tomography was done 3 and 12 months after intervention. All patients were evaluated by dimercapto-succinic acid renal scintigraphy 6 weeks and 12 months after intervention. A total of 94 patients were prospectively randomized to percutaneous nephrolithotomy (31), shock wave lithotripsy (31) and observation (32). Mean +/- SD followup was 19.3 +/- 5 months (range 12 to 29). In the percutaneous nephrolithotomy group all patients were stone-free at month 12. Scintigraphy revealed a scar in 1 patient (3.2%) on month 3 followup imaging. In the shock wave lithotripsy group the stone-free rate was 54.8%. Scintigraphy revealed scarring in 5 patients (16.1%). In the observation group 7 patients (18.7%) required intervention during followup. Median time to intervention was 22.5 +/- 3.7 months (range 18 to 26). One patient (3.1%) had spontaneous stone passage. Scintigraphy did not reveal scarring in any patient. Stone related events were noted in more than 20% of patients with asymptomatic lower caliceal stones observed expectantly. To manage lower caliceal stones percutaneous nephrolithotomy has a significantly higher stone-free rate with less renal scarring than shock wave lithotripsy. Thus, patients with asymptomatic lower caliceal stones must be informed in detail about all management options, especially focusing on percutaneous nephrolithotomy with its outstanding outcome.

Validation of a High Fidelity Adult Ureteroscopy and Renoscopy Simulator

Surgical simulation technology may efficiently train and accurately assess the acquisition of many skills. Surgical simulators often lack realism and can be expensive at $3,000 to more than $60,000. We assessed the face, content and construct validity of a newly developed, anatomically accurate, reasonably priced high fidelity ureteroscopy and renoscopy trainer. A total of 46 participants, including attending urologists, urology residents, medical students and industry representatives, assessed the face and content validity of the simulator using a standard questionnaire. Ten experienced ureteroscopists with greater than 30 procedures per year and 10 novice ureteroscopists with 0 were assessed on the ability to perform flexible ureteroscopy, renoscopy and intrarenal basket extraction of a lower pole calculus using the adult ureteroscopy trainer (Ideal Anatomic Modeling, Holt, Michigan). Subject performance was assessed by an experienced ureteroscopist using a checklist, global rating scale and time to task completion. Of participants 100% rated the trainer as realistic and easy to use, and thought it was a good training tool, 98% thought that it would serve as a good training format and 96% would recommend it to urology trainees. All participants recommended it for use in residency programs and 96% would or would have used it during residency. Only 37.5% vs 100% of experienced vs novice ureteroscopists would use it to practice. Of participants 9% foresaw a problem with the trainer. On the trainer experienced ureteroscopists scored significantly higher on the global rating scale (mean +/- SD 33.1 +/- 1.3 vs 15.0 +/- 2.7, p <0.0001) and checklist (4.1 +/- 1.0 vs 2.4 +/- 1.1, p = 0.004), and required less time to complete the task (141.2 +/- 40.1 vs 447.2 +/- 301.7 seconds, p = 0.01). Our preliminary study suggests the face, content and construct validity of the adult ureteroscopy trainer as a high fidelity ureteroscopy and renoscopy trainer.

Skin to Stone Distance Is an Independent Predictor of Stone-Free Status Following Shockwave Lithotripsy

In recent years several new parameters such as Hounsefield unit density and skin to stone distance (SSD) have been determined to correlate with successful extracorporeal shockwave lithotripsy (SWL). SSD has been shown to independently predict successful SWL for lower pole calculi. The objective of this study was to determine which stone characteristics on noncontrast computed tomography (NCCT), including SSD, independently predict for SWL success regardless of stone location within the kidney. A retrospective review of all 1282 SWL procedures between 2004 and 2007 at a single institution revealed 83 patients meeting inclusion criteria for current study. All patients were treated using a single electromagnetic lithotriptor (DoLi 50; Dornier Medical Systems, Marrieta, GA) with a single technician. Stone-free (SF) status was determined by NCCT or abdominal plain film radiographs at 6 weeks post-SWL. Logistic regression analysis was computed to assess SF rates using SSD, stone size, location, and Hounsefield unit density as predictors. Of the 83 patients, 51 were SF and 32 had residual stones at a mean follow-up of 2.3 months. The mean SSD in the SF group was 83.3 +/- 21.9 mm in comparison to those in the residual stone group who had a mean SSD of 107.7 +/- 28.9 mm (p < or = 0.05). Multivariate logistic regression analysis revealed that SSD was the only significant independent predictor of treatment outcome. SSD is an easily measured parameter on NCCT that independently correlates with SWL efficacy in treating stones in all locations.

O que há de novo no diagnóstico e tratamento da litíase urinária?

To update some aspects of the diagnosis and management of urinary lithiasis. A review of the main articles published in PubMed indexed journals was performed. The occurrence of urinary stones is higher among patients with body mass index above 30. Urinary stones are correctly diagnosed by non-contrast CT in 98% of the cases. SWL is the best method for treatment of renal stones smaller than 2 cm with tomographic density under 1000 HU except for stones located at the lower renal pole where the limit is 1 cm. PCNL reaches a stone-free rate between 60% and 100% for renal stones larger than 2 cm. Semirigid ureteroscopy renders patients with distal ureteral stones free in up to 94% of the cases compared to 74% of SWL. Regarding upper ureteral stones, ureteroscopy promotes stone-free rates between 77% and 91%and SWL between 41% and 82%. The link between urinary stones, obesity and diabetes mellitus is well established. Non-contrast CT is the gold standard for diagnosis of urinary stones. SWL is the mainstay in the treatment of renal stones with less than 2 cm and density under 1000 Hounsfield Units, except for lower pole calculi where the limit is 1 cm. PCNL is the preferred method for treatment of renal stones larger than 2 cm. Semirigid ureteroscopy is the method of election for lower ureteral stones; flexible ureteroscopy is reserved for upper ureteral or renal stones with less than 1.5 cm non responsive to SWL or for those patients with contraindications to PCNL.

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Pediatric Flexible Ureteroscopic Lithotripsy: The Children's Hospital of Philadelphia Experience

Therapeutic options currently available for urinary stones include shock wave lithotripsy, percutaneous nephrolithotomy and ureteroscopic treatment. While these treatment options have become the standard of care in the adult population, the same has not necessarily been applied to the pediatric population, despite an increasing prevalence of stone disease in children. We report our flexible ureteroscopic experience with urinary stones in children. A total of 170 ureteroscopic treatments were performed. Demographic information was collected. Stone burden was measured in millimeters. Operative access, operative times, intraoperative complications, stone-free status and postoperative complications were evaluated. A total of 167 children (89 boys and 78 girls) underwent 170 ureteroscopic procedures for urinary calculi. Mean patient age was 62.4 months at the time of the procedure (range 3 to 218). Mean followup was 19.7 months (range 6 to 39). Mean stone burden was 6.12 mm (range 3 to 24), with an average of 1.3 stones per patient. Retrograde access could not be obtained in 95 of the children (57%). No ureters were actively dilated. Flexible ureteroscopy was performed in all cases regardless of stone location. Stone clearance was 100% for stone burdens 10 mm or less and 97% for burdens greater than 10 mm after 1 ureteroscopy. Pediatric ureteroscopy is a safe and efficacious modality in the treatment of all upper urinary tract calculi, including lower pole calculi.

First Digital Flexible Ureterorenoscope: Initial Experience

Flexible ureterorenoscopy is a minimally invasive procedure that is rapidly gaining popularity as a treatment for patients with upper urinary tract lithiasis. One of the main drawbacks is the limited visualization imposed by fiberoptic technology in an endoscope, often only 7 to 8F and the fragility of fiber-based optics in a flexible endoscope. We report our initial experience with digital flexible URS and holmium laser lithotripsy using digital image capture in three patients. Two patients had upper tract calculi (1 cm lower pole calculus and 8 mm caliceal diverticular stone, respectively), and one patient underwent diagnostic URS. After basket capture and intrarenal relocation of the lower pole stone, complete stone destruction was achieved. Similarly, the caliceal diverticular stone was destroyed after holmium laser incision of the caliceal diverticulum. Remarkable improvement in image quality was observed throughout the procedures in comparison with current fiberoptic image acquisition. Minor image interference was noted during fluoroscopic screening, which increased slightly during laser activation. The first digital flexible ureterorenoscope provided excellent image quality and zoom capability, with a substantial improvement compared with fiberoptic technology. It does not require a separate light source and is an important step for the continued evolution of flexible URS as a therapeutic modality for upper urinary tract pathology.

Lower pole calculi larger than one centimeter: Retrograde intrarenal surgery

Controversy remains on how to treat lower pole calculi between 1 and 2 cm of size. Treatment options like shock wave lithotripsy (SWL) or percutaneous stone treatment (PCNL) are associated with poor stone-free rates or high morbidity.Due to the ongoing development in endourologic technology, especially in flexible renoscopy, laser technique and grasping devices (tipless Nitinol baskets) retrograde intrarenal surgery (RIRS) has become an option in treating these patients.Based on personal experience and an overview of the published literature we discuss RIRS as a valuable alternative to PCNL in treating patients with larger calculi of the lower pole.The technical developments in laser technology as well as significant improvement in flexible renoscopes have made RIRS for larger lower pole stones possible. The low complication rate gives RIRS for lower pole stones superiority over the invasive percutaneous approach, which is associated with significant morbidity, even in experienced hands.