What kind of stone prevention for whom? Risk-adjusted metaphylaxis following urinary stone disease

Approximately 5% of the German population suffers from urinary stone disease, but only 25% of these urolithiasis patients are at risk of recurrent stone disease or a severe metabolic disorder. It is important that patients at high risk are picked up early, so that appropriate therapy and measures designed to prevent secondary stone disease can be implemented. Risk classification is easily achieved by combining stone analysis with a basic diagnostic program. Patients at low risk need no further diagnostic evaluation or treatment, so that it is enough to recommend general metaphylaxis in these cases. In contrast, patients at high risk require additional specific aftercare and should be evaluated with the aid of a comprehensive diagnostic program from the start to allow precise definition of the metabolic targets.     

Does volume matter? Incorporating estimated stone volume in a nomogram to predict ureteral stone passage

IntroductionRecent studies have shown that software-generated 3D stone volume calculations are better predictors of stone burden than measured maximal axial stone diameter. However, no studies have assessed the role of formula estimated stone volume, a more practical and less expensive alternative to software calculations, to predict spontaneous stone passage (SSP).MethodsWe retrospectively included patients discharged from our emergency department on conservative treatment for ureteral stone (≤10 mm). We collected patient demographics, comorbidities, and laboratory tests. Using non-contrast computed tomography (CT) reports, stone width, length, and depth (w, l, d, respectively) were used to estimate stone volumes using the ellipsoid formula: V=ϖ*l*w*d*0.167. Using a backward conditional regression, two models were developed incorporating either estimated stone volume or maximal axial stone diameter. A receiver operator characteristic (ROC) curve was constructed and the area under the curve (AUC) was computed and compared to the other model.ResultsWe included 450 patients; 243 patients (54%) had SSP and 207 patients (46%) failed SSP. The median calculated stone volume was significantly smaller among patients with SSP: 25 (14–60) mm³ vs. 113 (66–180) mm³ (p<0.001). After adjusting for covariates, predictors of retained stone included: neutrophil to lymphocyte ratio (NLR) ≥3.14 (odds ratio [OR] 6, 95 % confidence interval [CI] 3.49–10.33), leukocyte esterase (LE) >75 (OR 4.83, 95% CI 2.12–11.00), and proximal stone (OR 2.11, 95% CI 1.16–3.83). For every 1 mm³ increase in stone volume, the risk of SSP failure increased by 2.5%. The model explained 89.4% (0.864–0.923) of the variability in the outcome. This model was superior to the model including maximal axial diameter (0.881, 0.847–0.909, p=0.04).ConclusionsWe present a nomogram incorporating stone volume to better predict SSP. Stone volume estimated using an ellipsoid formula can predict SSP better than maximal axial diameter.     

Stone burden in an average Swedish population of stone formers requiring active stone removal: how can the stone size be estimated in the clinical routine?

OBJECTIVE: To get information on the distribution of stone burdens in an average and representative group of Swedish stone forming patients requiring active removal of stones from the kidneys or ureters and to compare different methods for assessing the stone burden. METHODS: A computerised device was used to measure the total stone surface area (A(measured)) of 599 stone situations in kidneys and ureters in a consecutive group of patients referred to active stone removal. These measurements were compared with the large and short transverse diameters of the greatest stone, the sum of the largest diameters of the stones, the arithmetically calculated surface area (A(calculated)) as well as with the stone-types (A-F) previously described. RESULT: There were 483 stone situations with one and 116 with more than one stone. The stones were found in 407 men and 192 women. In 343 cases were the stones on the left side and in 256 on the right side. There were 34 staghorn stones. Of the examined stone situations 250 were in the kidney and 349 in the ureter. An A(measured) above 300 mm(2) was recorded in 7% of all stone situations. The corresponding numbers for A(measured) above 200 mm(2), 500 mm(2) and 700 mm(2) were 13%, 4% and 3%, respectively. When staghorn stones were excluded, good correlations were recorded for all variables but the best correlation was found between A(measured) and A(calculated). A revision of the previously published stone-type subgroups is suggested based on the following limits for the stone surface area: A < or = 30 mm(2), B = 31-300 mm(2), C = 301-700 mm(2) and D > 700 mm(2). CONCLUSION: The distribution of stone situations with different stone burden in an average Swedish population is described. With the exception of staghorn stones and stones with extremely irregular form an acceptable estimate of the stone surface are can be arithmetically derived from the length and the width of the stone.     

What foods should stone formers avoid?

Urolithiasis is a disease that has a high recurrence rate. We think that dietary guidance is necessary for the prevention of urolithiasis. It is important that stone formers eat a well-balanced diet and proper quantity of foods.     

Pelvicaliceal anatomical variation between stone bearing and normal contralateral kidneys--does it have an impact on stone formation in pediatric patients with a solitary lower caliceal stone?

PURPOSE: We aimed to investigate the probable effect of pelvicaliceal anatomical differences between stone bearing and normal contralateral kidneys on the etiology of stone formation in children with a solitary lower pole caliceal stone. MATERIALS AND METHODS: We reviewed the clinical records of 25 pediatric patients who underwent SWL for a solitary lower caliceal stone and 15 healthy pediatric patients who served as controls. Lower pole IPA, IL and IW, together with other caliceal variables obtained from the pelvicaliceal anatomy of the stone bearing and contralateral normal kidneys of patients with urolithiasis, and both kidneys of the control group were measured based on excretory urography. Also, total pelvicaliceal volume for both kidneys was calculated. RESULTS: Mean LIPAs of stone bearing kidneys compared to the normal contralateral kidneys was more acute, equal and wider in 52%, 16% and 32% of the patients, respectively. Mean pelvicaliceal volumes of the stone forming and normal kidneys were 1,553.8 mm(3) (range 242 to 7,107) and 581.0 mm(3) (90 to 2,662), respectively, and there was statistical significance only in pelvicaliceal volumes between the stone bearing and contralateral normal kidneys (p <0.001). CONCLUSIONS: Our results reveal that IPA, IL and IW of calices do not have an effect on stone formation in pediatric patients. However, large pelvicaliceal volume seems to be a significant risk factor for stone formation in the lower calix, probably because it creates abnormal urodynamic and morphological features, especially when accompanied by other metabolic abnormalities.     

Upper urinary tract stone disease in patients with poor performance status: active stone removal or conservative management?

Background

It remains controversial as to whether active stone removal should be performed in patients with poor performance status because of their short life expectancy and perioperative risks. Our objectives were to evaluate treatment outcomes of active stone removal in patients with poor performance status and to compare life prognosis with those managed conservatively.

Methods

We retrospectively reviewed 74 patients with Eastern Cooperative Oncology Group performance status 3 or 4 treated for upper urinary tract calculi at our four hospitals between January 2009 and March 2016. Patients were classified into either surgical treatment group or conservative management group based on the presence of active stone removal. Stone-free rate and perioperative complications in surgical treatment group were reviewed. In addition, we compared overall survival and stone-specific survival between the two groups. Cox proportional hazards analysis was performed to investigate predictors of overall survival and stone-specific survival.

Results

Fifty-two patients (70.3%) underwent active stone removal (surgical treatment group) by extracorporeal shock wave lithotripsy (n = 6), ureteroscopy (n = 39), percutaneous nephrolithotomy (n = 6) or nephrectomy (n = 1). The overall stone-free rate was 78.8% and perioperative complication was observed in nine patients (17.3%). Conservative treatment was undergone by 22 patients (29.7%) (conservative management group). Two-year overall survival rates in surgical treatment and conservative management groups were 88.0% and 38.4%, respectively (p < 0.01) and two-year stone-specific survival rates in the two groups were 100.0% and 61.3%, respectively (p < 0.01). On multivariate analysis, stone removal was not significant, but was considered a possible favorable predictor for overall survival (p = 0.07). Moreover, stone removal was the only independent predictor of stone-specific survival (p < 0.01).

Conclusions

Active stone removal for patients with poor performance status could be performed safely and effectively. Compared to conservative management, surgical stone treatment achieved longer overall survival and stone-specific survival.

     

Is prevention of stone recurrence financially worthwhile?

This review shows that the cost of relying solely on minimally-invasive urological procedures for removing stones when patients return with recurrent stones is considerable and is significantly greater that that incurred by screening already proven recurrent stone-formers to identify the risk factors that are causing their stones and then instituting prophylactic measures to prevent stone recurrence. In the UK, at 1998 prices (when the original survey was carried out) for every stone episode prevented, there is a potential saving of almost ￡2,000 to the local Health Authority concerned. In spite of this, many Health Authorities have taken the liberty to discontinue comprehensive stone screening within the past 20 years under the mistaken supposition that minimally-invasive techniques for removing stones have “solved the stone problem”. At UCLH in London where such a comprehensive scheme has been in place for the past 8 years, savings of up to ￡250,000 per year can be made by identifying the particular lifestyle as well as the epidemiological, metabolic and nutritional risk factors involved in a given patient and then instituting appropriate measures to prevent further stones.     

Is there a role for open stone surgery?

Modern day urinary-stone treatment involves procedures and techniques that were not even available 20 years ago. The relatively rapid and sometimes explosive development of ESWL, percutaneous techniques, and ureteroscopy and intracorporeal lithotripsy has ushered in the era of minimally invasive stone management. In many regards, open surgery has such a limited role that its performance often is regarded as a sign of failure. To think of open stone surgery in this manner is likely to do a disservice to a small but important segment of the urinary-stone patient population. The critical responsibility of the urologist treating stone disease is to be able to recognize those clinical situations in which open stone surgery may represent at least a viable and reasonable alternative to less-invasive modalities. The duty of the surgeon is then to be able to present this option to the patient in an unbiased fashion and to effectively perform and implement this form of treatment if chosen. It is only with this approach that open surgery will continue to be correctly applied on those rare occasions and will not become a lost surgical art in the era of minimally invasive surgery.     

Is stone clearance after shockwave lithotripsy in patients with solitary upper-caliceal stone influenced by anatomic differences in the pelvicaliceal system?

PURPOSE: We investigated the effect of pelvicaliceal differences on stone clearance after extracorporeal shockwave lithotripsy (SWL) in patients with solitary upper-caliceal stones. PATIENTS AND METHODS: The clinical records of patients with solitary upper-caliceal stones who underwent SWL between 1996 and 2004 were reviewed. After excluding patients with hydronephrosis, significant anatomic abnormalities, non-calcium stones, metabolic abnormalities, recurrent stone disease, multiple stones, and previous renal surgery, 42 patients with a mean stone size of 153.47 mm2 (range 20-896 mm2) were enrolled in this study. They were divided into three groups according to stone burden (group 1 < or =100 mm2, group 2,101 mm2-200 mm2, and group 3 >200 mm2). Upper-pole infundibulopelvic angle (IPA), infundibular length (IL), and infundibular width (IW) were measured from intravenous urograms. Results: Of the total, 29 patients (69%) were stone free after SWL treatment. The differences in the upperpole IPA, IL, and IW of stone-free patients and patients with residual stones were not statistically significant (P = 0.85, P = 0.89, and P = 0.37, respectively). Again, there were no statistically significant differences in terms of upper IPA, IW, and IL in comparing the three groups divided by initial stone size. Conclusion: Upper-caliceal anatomy does not exert a significant impact on stone clearance after SWL for isolated upper-caliceal stones. To best of our knowledge, this is the first study to investigate the effects of pelvicaliceal anatomy on SWL treatment for upper-caliceal stones, so there is a need for further investigations to confirm our findings.     

Brushite stone disease as a consequence of lithotripsy?

The incidence of calcium phosphate (CaP) stone disease has increased over the last three decades; specifically, brushite stones have been diagnosed and treated more frequently than in previous years. Brushite is a unique form of CaP, which in certain patients can form into large symptomatic stones. Treatment of brushite stones can be difficult since the stones are resistant to shock wave and ultrasonic lithotripsy, and often require ballistic fragmentation. Patients suffering from brushite stone disease are less likely to be rendered stone free after surgical intervention and often experience stone recurrence despite maximal medical intervention. Studies have demonstrated an association between brushite stone disease and shock wave lithotripsy (SWL) treatment. Some have theorized that many brushite stone formers started as routine calcium oxalate (CaOx) stone formers who sustained an injury to the nephron (such as SWL). The injury to the nephron leads to failure of urine acidification and eventual brushite stone formation. We explore the association between brushite stone disease and iatrogenic transformation of CaOx stone disease to brushite by reviewing the current literature.     

Is pre-operative imaging essential prior to ureteric stone surgery?

INTRODUCTION

The aim of this study was to identify patients not requiring ureteric stone surgery based on pre-operative imaging (within 24 hours) prior to embarking on semirigid ureteroscopy (R-URS) for urolithiasis.

METHODS

The imaging of all consecutive patients on whom R-URS for urolithiasis was performed over a 12-month period was reviewed. All patients had undergone a plain x-ray of the kidney, ureters and bladder (KUB), abdominal non-contrast computed tomography (NCCT-KUB) or both on the day of surgery.

RESULTS

A total of 96 patients were identified for the study. Stone sizes ranged from 3mm to 20mm. Thirteen patients (14%) were cancelled as no stone(s) were identified on pre-operative imaging. Of the patients cancelled, 8 (62%) required NCCT-KUB to confirm spontaneous stone passage.

CONCLUSIONS

One in seven patients were stone free on the day of surgery. This negates the need for unnecessary anaesthetic and instrumentation of the urinary tract, with the associated morbidity. Up-to-date imaging prior to embarking on elective ureteric stone surgery is highly recommended.     

Large fibres in urinary calculi — Promoters of stone formation

Summary Large fibres (ø 10–20 m, length up to 5,000 m) are sometimes imbedded in urinary calculi. It may be that these fibres can catch sediment particles and promote stone growth. By scanning electron microscopy the morphology of the fibres was studied as well as the relationship of the fibres with crystalline stone components. The reported findings suggest that the fibres are possibly formed in the tubuli as the result of an hitherto unknown defect.     

Spontaneous stone passage: is it Ammi visnaga effect?

Ammi visnaga was used in Ancient Egypt as an herbal remedy for renal colic. “Khellin”, a chemical obtained from Ammi visnaga, was used as a smooth muscle relaxant and has been thought to have pleiotropic effects on urolithiasis. We report a case with multiple ureteral stone passages possibly as a result of medication with an herb preparation, Khellin.