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At least 37 records · Page 2Linked to original sources

PubMed1997

[Stone recurrence after stone free status with extracorporeal shock wave lithotripsy].

BACKGROUND: The objects of this study is to evaluate the ipsilateral stone recurrence who became stone free status after extracorporeal shock wave lithotripsy (ESWL). METHODS: Three hundred ninety five patients who became stone free after ESWL with Lithostar and followed more than 6 months, were analyzed stone recurrence. Stone recurrence were diagnosed by KUB and/or ultrasound. Actual recurrence free rate were calculated based on the period from the day of achieved stone free status to the day of estimated recurrence. Eight factors examined included sex, side, number, location, size, stone history urological complication, hydronephrosis and also contralateral recurrence was analyzed. RESULTS: Over all ipsilateral recurrence free rate were 96.5%, 78.8%, 65.3% after 1, 3 and 5 years, respectively. Contralateral stone free rate were 98.1%, 92.5%, 87.2% after 1, 3 and 5 years. Five-year recurrence free rate according stone factors, there were significant difference in stone number (Single 71.1% and multiple 31.6%), in stone history (with history 77.1% and without 35.7%), in urological complication (without complication 67.7% and with complication 35.7%). However, there were no significant difference in sex, side, stone, location, stone size and hydronephrosis. CONCLUSION: This results suggested that the stone number, stone history and urological complication were highly related to ipsilateral stone recurrence after stone free status by ESWL. Extracorporeal shock was lithotripsy had probability of higher stone recurrence rate.

Adolescent↗

PubMed1991

[Extracorporeal shock wave lithotripsy for ureteral stones and cystine stones].

We report our experience with extracorporeal shock wave lithotripsy (ESWL) in the treatment of ureteral and cystine stones, which are known to be difficult to treat by this method. First, in order to determine the effectiveness of the ureteral catheter in the destruction of ureteral stones, we compared the clinical results of 121 patients treated without the catheter and 141 patients inserted with the catheter. There was no significant difference in the success rate between the two groups regardless of stone size, which indicates that the use of the ureteral catheter had no effect on the outcome of treatment. We then studied the clinical results of impacted ureteral stones which are especially difficult to destroy. Excretory urography was performed to non-invasively diagnose these stones, and those without visualization in the ureter below the stone were diagnosed as impacted stones and treated by ESWL without the ureteral catheter. Among the stones with a diameter of 1 to 2 cm, the success rate was significantly lower in impacted stones compared to non-impacted stone. These findings suggest that ESWL treatment without the ureteral catheter may be effective for ureteral stones with a diameter of less than 1 cm and non-impacted stones with a diameter of 1 to 2 cm, while combination therapy with other methods such as TUL may be better for other stones. We also performed ESWL on 6 patients with renal stones and 2 patients with ureteral stones which were cystine stones. Renal stones required an average 4.1 treatment with an average of 1,875 shocks per treatment, and ureteral stones required 1.5 treatment with an average of 1,833 shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Endoscopic treatment of bile duct stones: is stone extraction necessary after endoscopic sphincterotomy?

BACKGROUND: The current treatment for stones in the biliary tree is endoscopic sphincterotomy (ES) followed by stone extraction with the help of balloon catheters or metal baskets. Stone extraction techniques are often associated with complications. Moreover, the balloon catheters break easily which aids to the cost of the procedure. The present study was designed to examine the effectiveness of endoscopic sphincterotomy (ES) alone in allowing spontaneous expulsion of bile duct stones and to determine the circumstances which warrant stone extraction. METHODS: Endoscopic retrograde cholangio-pancreatography (ERCP) was attempted in 68 patients with stones in the common bile duct. The stone size was determined by ultrasound, cholangiography in post cholecystectomy patients with a T-tube or by ERCP. Patients with stone size of 15 mm or less in diameter were treated with ES alone without stone extraction. Patients were discharged from the hospital within 24 hrs and returned for reassessment every week or earlier, if symptomatic, until complete clearance of stones was demonstrated. RESULTS: Endoscopic sphincterotomy was successfully performed in 63 (93%) patients, the procedure was abandoned in the remaining 5 patients for technical reasons. Spontaneous clearance of stones was observed in 55 (87%) patients, usually without any accompanying pain (47.85%). Persistent stones were seen in 8 (13%) patients; extension of the ES resulted in spontaneous stone expulsion in 6 of these patients. Thus, 61 (97%) of the 63 patients with stones of 10 mm or less in size cleared the stones spontaneously and all 8 patients who failed the initial ES, had stones > 10 mm in size. COMMENT: The present study shows that all small stones (< 10 mm) and most of those < 15 mm are expelled spontaneously after an adequate ES. These finding if substantiated by larger studies will reduce considerably the cost of the procedure as well as the morbidity associated with mechanical stone extraction.

Adolescent↗

PubMed2005

Ultracal-30 gypsum artificial stones for research on the mechanisms of stone breakage in shock wave lithotripsy.

Artificial stones are used in research on the mechanisms of stone breakage in shock wave lithotripsy (SWL) and in assessing lithotripter performance. We have adopted Ultracal-30 gypsum as a model, finding it suitable for SWL studies in vitro, acute animal experiments in which stones are implanted in the kidney, and as a target to compare the in vitro performance of intracorporeal lithotripters. Here we describe the preparation of U-30 stones, their material properties, shock wave (SW) breakage characteristics, and methods used for quantitation of stone fragmentation with this model. Ultracal-30 gypsum cement was mixed 1:1 with water, cast in plastic multi-well plates, then, the stones were liberated by dissolving the plastic with chloroform and stored under water. Stone breakage in SWL was assessed by several methods including measures of the increase in projected surface area of SW-treated stones. Breakage of hydrated stones showed a linear increase in fragment area with increased SW-number and SW-voltage. Stones stored in water for an extended time showed reduced fragility. Dried stones could be rehydrated so that breakage was not different from stones that had never been dry, but stones rehydrated for less than 96 h showed increased fragility to SWs. The physical properties of U-30 stones place them in the range reported for natural stones. U-30 stones in vitro and in vivo showed equivalent response to SW-rate, with approximately 200% greater fragmentation at 30 SW/min compared to 120 SW/min, suggesting that the mechanisms of SW action are similar under both conditions. U-30 stones provide a convenient, reproducible model for SWL research.

Calcium Sulfate↗

PubMedDate not supplied

Mucin content in gallbladders with brown pigment stones or combination stones with a brown periphery.

BACKGROUND/AIMS: Gallbladder mucus itself has been recognized to play an important role in gallstone development. Despite the diverse mechanisms of stone induction and the differences in stone composition, there is a quantitative increase in the epithelial mucus production period before stone formation. As brown pigment stones are found frequently in gallstone disease, we conducted a study on gallbladders with brown pigment stones or combination stones with a brown periphery to evaluate the mucin content in the gallbladder epithelium in comparison to gallbladders with cholesterol stones and those without stones. METHODS: Gallbladder specimens were fixed in 10% formalin immediately after cholecystectomy and then embedded in paraffin. The specimens were sectioned for periodic acid-Schiff-alcian blue (PAS-AB, pH 2.5) double stain to evaluate the intra-epithelial mucin content. The PAS-AB index was calculated as a proportion of the PAS-AB-positive mucin area to the total epithelial area, using a computerized image analyzer. RESULTS: Evaluation of the PAS-AB index on the lining epithelia of gallbladders showed that it was 32.43 +/- 9.96% in gallbladders with brown stones, which is significantly (p < 0.001) higher than in gallbladders with cholesterol stones (15.63 +/- 6. 75%) and gallbladders without stones (9.55 +/- 4.77%). CONCLUSION: The results show that gallbladders with brown stones contain more abundant mucin than gallbladders with cholesterol stones or those without stones. They also suggest that the gallbladder epithelium per se might play a more important role in stone formation in those with brown stones than in those with cholesterol stones.

Adult↗

PubMed1993

Endoscopic extraction of bile duct stones: management related to stone size.

Endoscopic sphincterotomy has become the first line treatment for patients with common bile duct (CBD) stones. This technique may fail, however, due to difficult anatomy, previous surgery, periampullary diverticula or the presence of a large stone. The importance of stone size to the success of endoscopic sphincterotomy has not been fully assessed. A prospective study was carried out over the period January 1987 to December 1989 on 100 patients (45 male, 55 female, median age 69 years, range 19-97) with CBD stones in which a policy of early duct clearance was followed. Endoscopic retrograde cholangiopancreatography (ERCP) was performed and the stone size and number recorded from the cholangiograms and corrected for magnification. Sphincterotomy was performed using a diathermy unit with a cutting current and stones were extracted using a balloon catheter or a Dormia basket. Of the 100 patients with CBD stones receiving ERCP, successful clearance of the biliary tree was possible in seven without endoscopic sphincterotomy and five were felt to be unsuitable for endoscopic sphincterotomy. Of the remaining 88 patients endoscopic sphincterotomy was successful in 75 (85%). Of the 75 patients having endoscopic sphincterotomy stone clearance was successful in 44 (59%). There were no deaths and only four complications, which rapidly resolved on conservative treatment (two acute pancreatitis, two bleeding). The number of CBD stones present was similar in those patients with successful endoscopic sphincterotomy and duct clearance (median 1, range 1-10, n = 44) as in those in whom it failed (median 2, range 1-6, n = 31). In contrast there was a highly significant difference when stone size was analysed (successful clearance median stone size 10 mm, range 3-27 mm; unsuccessful: median 18 mm, range 10-42, p<0.001). Stones less than 10 mm in diameter (n=21) were all removed successfully whereas in patients with stones over 15 mm (n=25) only three were removed endoscopically (12%). All patients with evidence of residual stones had additional treatment. Of these 31 patients, 10 had surgery, 11 had insertion of an endoprosthesis, and 10 had dissolution treatment with methyl-tert-butyl ether through a nasobiliary catheter. This study shows the importance of stone size to the success rate of endoscopic removal of bile duct stones.

Adult↗

PubMed2003

Stone recurrence predictive score (SRPS) for patients with calcium oxalate stones.

PURPOSE: We developed a convenient, self-administered 8-item stone recurrence predictive score (SRPS) to predict the recurrence of calcium oxalate stones. MATERIALS AND METHODS: An 8-item SRPS to predict stone recurrence was developed based on general patient data, including age, sex, urine volume, smoking, wine drinking, family history, stone number and history of gouty arthritis. Mean age of the 204 studied patients with calcium oxalate stones +/- SD was 59.4 +/- 14.5 years (range 24 to 83). The male-to-female ratio was 3:1. Of the patients 115 were recurrent stone formers and 89 were single stone formers. We compared all available general data in the recurrence and control groups. RESULTS: Family history, stone number, gouty arthritis and SRPS were independent risk factors for stone recurrence. Mean SRPS in recurrent and single stone formers was 7.6 +/- 3.1 and 5.1 +/- 2.0, respectively (p = 0). An increase in SRPS had a significant positive correlation with stone recurrence (r2 = 0.859, p <0.0001). At an SRPS cutoff of 7 or greater we achieved 61.7% sensitivity and 75.3% specificity to predict stone recurrence. At an SRPS of 11 or greater we found that 100% of patients had recurrent stones. CONCLUSIONS: With the introduction of the 8-item SRPS we provide a simple, convenient and reliable tool to predict calcium oxalate stone recurrence. Due to the characteristics of the high incidence of stone recurrence thorough metabolic evaluation may be justified in patients with an SRPS of 7 or greater and preventive measures are highly recommended in those with an SRPS of 11 or greater.

Adult↗

PubMed2000

Helical CT of urinary calculi: effect of stone composition, stone size, and scan collimation.

OBJECTIVE: Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS: One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS: At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (<approximately 6 mm) and other stones (< approximately 4 mm) had very low attenuation, so low that they could remain undetected on helical CT. The model predicted well the degree that attenuation was affected by stone size and collimation width. CONCLUSION: Stone composition and stone size, relative to CT collimation, independently influenced CT attenuation. The effect of stone size and collimation generally conformed to the model's predictions. We determined that small stones with low attenuation can be overlooked on helical CT.

Humans↗

PubMed1985

The severity of infection stones compared to other stones in the upper urinary tract.

A retrospective study of the case records of 391 adult patients with spontaneously passed or surgically removed concrements from the upper urinary tract during the period 1982-1983 was performed. According to chemical analysis, 66% of the stones were calcium stones, 30% were infection stones, 4% were uric acid/urate stones and 1% were cystine stones. Of the infection stones 12 (10%) were staghorn calculi. The infection stones placed a greater strain on the patients than the calcium stones. Thus, infection stones were significantly more often recurrent stones and required surgery significantly more often than the calcium stones. Only 6% of the patients with infection stones had proved abnormalities predisposing to upper urinary tract infection. Urinary tract infection with a urease-producing microorganism was detected in only 52% of the patients with infection stones. As infection with a urease-producing microorganism is a prerequisite for the formation of infection stones in the urinary tract a careful microbiological investigation to find and treat the infection responsible for the stone formation is mandatory.

Adolescent↗

PubMed2002

The Dretler stone cone: a device to prevent ureteral stone migration-the initial clinical experience.

PURPOSE: Retrograde stone migration during ureteroscopic lithotripsy occurs in 5% to 40% of proximal and distal ureteral stone cases. This migration increases morbidity and the need for auxiliary procedures. The Dretler stone cone (Medsource, Norwell, Massachusetts) is a novel device to prevent proximal stone migration and facilitate fragment extraction during ureteroscopic lithotripsy. We assessed the safety and efficacy of the Dretler stone cone in the clinical setting and compared it prospectively with a conventional flat wire basket during ureteroscopy for ureteral calculi. MATERIALS AND METHODS: To our knowledge we report the initial clinical use of the Dretler stone cone in 50 consecutive patients with ureteral calculi undergoing ureteroscopic extraction. Calculi were situated above the sacroiliac joint in 24 cases, over the sacroiliac joint in 15 and below the sacroiliac joint in 11. Pneumatic lithotripsy was done in 42 cases. In the remaining 8 cases ureteroscopic (3) or fluoroscopic (5) intact stone extraction was performed. The later 23 cases using the Dretler stone cone were prospectively compared with 20 of ureteroscopic intracorporeal lithotripsy using a standard flat wire basket. RESULTS: The Dretler stone cone was successfully placed in all 50 cases. In 41 patients it was placed via cystoscopy under fluoroscopic guidance, while 9 impacted stones required ureteroscopic placement. Six patients in whom the Dretler stone cone was used had residual fragments less than 3 mm. No patient required auxiliary procedures. In the prospective trial no patients in Dretler stone cone group had residual fragments greater than 3 mm. or required auxiliary procedures. However, in the flat wire basket group residual stones greater than 3 mm. were present in 6 cases (30%, p <0.001), while auxiliary procedures were required in 4 (20%, p <0.01). CONCLUSIONS: The Dretler stone cone represents a new generation of basketry that minimizes proximal ureteral stone migration and allows safe extraction of fragments during ureteroscopic lithotripsy. In our experience it is associated with a lower incidence of significant residual fragments and fewer auxiliary procedures than conventional flat wire baskets.

Adult↗

PubMed2004

Correlation between urinary tract pure stone composition and stone morphology on plain abdominal film.

BACKGROUND: Crystallographic composition of urinary tract stone varies in several chemical groups and determines the degree of fragmentation to extracorporeal shock wave lithotripsy (ESWL) which has been widely used for the treatment of renal and ureteral calculi. Visual prediction of stone composition by its morphology from plain radiograph may provide a simple method and clinical hint to decide therapeutic modalities. A prospective study was designed to determine the correlation of stone composition with its radiographic morphology. METHODS: One hundred patients of urolithiasis with passage of stone fragments (after ESWL, surgical lithotomy or endoscopic lithotripsy) analyzed as pure stone by infrared spectrometry were reviewed by plain abdominal film to classify their morphology, location and size. Five experienced surgeons familiar with the radiographic patterns of different types of pure stones were invited to predict the stone composition on plain abdominal film. RESULTS: Five different patterns of radiographic appearances of the stones were identified. Calcium oxalate monohydrate referred to the smooth-shaped and homogeneous ones with denser opacity. Calcium oxalate dihydrate referred to those smaller ones that had irregular margin with stippled border and were less dense. Calcium phosphate (CaP) had moderate density and size without significant figures. Struvite meant staghorn stone; usually bilateral. Uric acid referred to those being radiolucent, slightly opacified, and in large size. The 5 surgeons achieved an overall accuracy of 27.4%. There was no obvious relations between accuracy and location or size of the stones. CaP stone was the most likely to be misclassified, and achieved only 20% accuracy. CONCLUSIONS: Different stone composition showed grossly specific radiographic appearances, but clinical test revealed poor correct rate in prediction of stone composition from plain abdominal film. The results of our study suggest that prediction of stone component based on stone morphology on plain abdominal film may not be accurate enough. Patient's clinical information and other laboratory data should be considered while interpreting plain abdominal film for better treatment choice of urolithiasis.

Calcium Oxalate↗

PubMed2005

Predictions of outcomes of renal stones after extracorporeal shock wave lithotripsy from stone characteristics determined by unenhanced helical computed tomography: a multivariate analysis.

The aim of our study is to analyze the relationships between the characteristics of renal stones determined by unenhanced helical computed tomography (UHCT) and their outcomes after extracorporeal shock wave lithotripsy (ESWL) as well as to predict ESWL outcomes of renal stones by their UHCT characteristics with the use of multivariate analysis. During a 7-month period, 80 adult patients with renal stones underwent ESWL as well as UHCT both before and 3 months after ESWL. Of the 80 patients, 42 patients were classified as ESWL successes and 38 as ESWL failures based on their post-ESWL UHCT findings. For pre-ESWL UHCT, a stone number of more than 2 (P=0.0236), a maximal stone size of greater than 12 mm (P<0.0001), a stone burden of more than 700 mm3 (P<0.0001), a maximal stone density of more than 900 HU (P=0.0008) and nonround/oval stones (P=0.0007) were associated with ESWL failure outcomes. Multivariate analysis demonstrated that a stone burden of more than 700 mm3 (P=0.0003), the presence of nonround/oval stones (P=0.0072) and a maximal stone density of more than 900 HU (P=0.0430) were statistically significant predictors of a failure outcome for ESWL. Thus, the analysis of stone characteristics of renal stones by UHCT is helpful in selecting appropriate patients undergoing ESWL for favorable outcomes and reduces the overall costs of the treatment of renal stones.

Adult↗

PubMed2005

Diagnosis and metaphylaxis of stone disease. Consensus concept of the National Working Committee on Stone Disease for the upcoming German Urolithiasis Guideline.

This review draws the recent state of the art in metabolic diagnosis and metaphylaxis of stone disease. It is the basis for the consensus approval with the other medical societies and institutions in Germany involved in the guideline process of the new "Urolithiasis Guideline". The German Working Committee on Stone Disease reviewed critically the current literature in the field of urolithiasis-including the existing German and EAU-Guidelines as well as the Conference Book of the First International Consultation on Stone Disease. As far as possible the references were rated according to the EBM criteria. On this basis the expert group discussed all pathways and statements regarding the management of stone disease. The present review coincides with the consented guideline draft of the German Working Committee on Stone Disease. Occurrence of stone disease in the western world increases seriously. Modern lifestyle, dietary habits and overweight-problems of the affluent societies-emerge to be the important promoters of the "stone-boom" in the new millennium. This even affects children, whose stone prevalence is otherwise significantly less than that of adults. Criteria for the high risk group of stone formers were clearly defined. A diagnostic standard is formulated for the basic and the elaborate metabolic evaluation of a stone patient. Approximately 75% of all stone patients could anticipate stone recurrence with elementary reorientation of their lifestyle and dietary habits, summarized as general metaphylaxis. About 25% of the stone formers require additional pharmacological intervention to normalize their individual biochemical risk, precisely compiled for each stone type as specific metaphylaxis.

Consensus↗

PubMed2006

Efficacy of extracorporeal shock wave lithotripsy for isolated lower caliceal stones in children compared with stones in other renal locations.

OBJECTIVES: To evaluate the efficacy of extracorporeal shock wave lithotripsy (ESWL) monotherapy for isolated lower caliceal calculi in a pediatric age group and compare it with that for isolated middle/upper caliceal and renal pelvic calculi. METHODS: We retrospectively reviewed the data of 151 renal units in 126 children treated with ESWL for isolated caliceal and renal pelvic stones from March 1992 to February 2004. The stones were localized in the lower, middle/upper calices, and renal pelvis in 50, 26, and 75 renal units, respectively. The results were compared with respect to renal location and stone burden. RESULTS: The median patient age was 8 years (range 1 to 16). The median stone burden in the lower and middle/upper caliceal groups was significantly lower than in the renal pelvis group at 0.6, 0.6, and 1 cm2, respectively (P = 0.002). The overall stone-free rate was 62% for lower calices, 65.3% for middle/upper calices, and 80% for renal pelvis stones. For the group with a stone size greater than 2 cm2, the stone-free rate decreased to 33% in both lower and middle/upper calices; however, it was almost the same in the renal pelvis (81.8%). A highly significant relation was found between the stone burden and number of sessions (P < 0.001), but none between the stone burden and stone-free rate. CONCLUSIONS: In our study, ESWL was equally effective for stones in all locations. We recommend ESWL as the primary treatment of choice for stones less than 2.0 cm2 in all caliceal locations. For the management of caliceal stones greater than 2.0 cm2, prospective randomized trials comparing ESWL and percutaneous nephrolithotomy are necessary.

Adolescent↗

PubMed2004

Efficacy of the Stone Cone for treatment of proximal ureteral stones.

BACKGROUND AND PURPOSE: Whereas ureteroscopic lithotripsy is more efficacious than SWL in treating lower-ureteral stones, the same has not been universally said of its ability to treat proximal ureteral stones. Because failed proximal lithotripsy is often attributable to the complications associated with stone migration into the renal pelvis and calices, an instrument that can prevent this migration is a potentially important tool in the ureteroscopic armamentarium. This study sought to assess the role of just such an instrument, the Stone Cone, in proximal-ureteral lithotripsy. PATIENTS AND METHODS: We treated 19 consecutive patients having proximal-ureteral stones using semirigid ureteroscopy, a Stone Cone Nitinol urologic retrieval coil, and holmium:YAG laser lithotripsy with a 200- or 365-microm fiber. In all patients, both the Stone Cone and the laser fiber were utilized under direct visual guidance through the working channel(s) of the ureteroscope. RESULTS: All 19 patients were rendered stone free after Ho:YAG laser lithotripsy in conjunction with a Stone Cone. No stone fragments were noted to migrate into the renal pelvis, and the Stone Cone did not break or become entrapped in any of the 19 cases. CONCLUSION: The Stone Cone is a powerful new tool for proximal-ureteral lithotripsy and will likely revolutionize the treatment of proximal-ureteral stones. The savings in morbidity, time, and money associated with not having to chase stone fragments using flexible ureteroscopy are considerable.

Female↗

PubMed2006

Lower-caliceal stone clearance index to predict clearance of stone after SWL.

BACKGROUND AND PURPOSE: There is no uniform consensus regarding the anatomic factors that influence the clearance rate of caliceal stones after SWL, as different authors have studied various independent factors separately. We correlated both favorable and unfavorable factors into a formula to predict the clearance rate. PATIENTS AND METHODS: A series of 56 consecutive patients (37 male, 19 female) with isolated lower-caliceal single stones (right 29, left 27) treated with SWL using the Dornier Compact Delta lithotripter were analyzed retrospectively. Of these, 40 patients had soft stones, and 16 patients had hard stones. The first stone-free rate (SFR) according to plain films and ultrasonography was analyzed by stone size, and a stone clearance index (SCI) formula was applied to see if there was any change in the SFR, especially for stones >2 cm. RESULTS: The formula, which correlated well with the clearance, is SCI = [(IVA x IW x stone type)/IH] - (stone size in mm(2)/10). Nearly all (90%) of the patients with an SCI of >0 cleared their stones within 3 months, and 87% of the patients with an SCI <0 cleared their stones after 3 months. Positive and negative predictive values were 93.33% and 76.9%, respectively. The accuracy of the correlation is 85.71%. CONCLUSIONS: The success of SWL for lower-caliceal stones can be predicted easily using the SCI. Stones of >200 mm(2) (>2 cm) surface area may still be suitable for SWL if the SCI is positive, whereas alternative treatment modalities should be considered if the SCI is a low negative value (<-7).

Evidence-Based Medicine↗

PubMed2004

Can we improve the prediction of stone-free status after extracorporeal shock wave lithotripsy for ureteral stones? A neural network or a statistical model?

PURPOSE: We evaluated whether an artificial neural network (ANN) can improve the prediction of stone-free status after extracorporeal shock wave lithotripsy (ESWL) (Dornier Medical Systems, Inc., Marietta, Georgia) for ureteral stones compared to a logistic regression (LR) model. MATERIALS AND METHODS: Between February 1989 and December 1998, 984 patients with ureteral stones, including 780 males and 204 females with a mean age +/- SD of 40.85 +/- 10.33 years, were treated with ESWL. Stone-free status at 3 months was determined by urinary tract plain x-ray and excretory urography. Of all patients 919 (93.3%) were free of stones. The impact of 10 factors on stone-free status was studied using an LR model and ANN. These factors were patient age and sex, renal anatomy, stone location, side, number, length and width, whether stones were de novo or recurrent, and stent use. An LR model was constructed and ANN was trained on 688 randomly selected patients (70%) to predict stone-free status at 3 months. The 10 factors were used as covariates in the LR model and as input parameters to ANN. Performance of the trained net and developed logistic model was evaluated in the remaining 296 patients (30%), who served as the test set. The sensitivity (percent of correctly predicted stone-free cases), specificity (percent of correctly predicted nonstonefree cases), positive predictive value, overall accuracy and average classification rate of the 2 techniques were compared. Relevant variables influencing the construction of the 2 models were compared. RESULTS: Evaluating the performance of the LR and ANN models on the test set revealed a sensitivity of 100% and 77.9%, a specificity of 0.0% and 75%, a positive predictive value of 93.2% and 97.2%, an overall accuracy of 93.2% and 77.7%, and an average classification rate of 50% and 76.5%, respectively. LR failed to predict any nonstone free cases. LR and ANN identified stone location and stent use as important factors in determining the outcome, while ANN also identified stone length and width as influential factors. CONCLUSIONS: ANN and LR could predict adequately those who would be stone-free after ESWL for ureteral stones. The neural network has a higher ability to predict those who fail to respond to ESWL.

Female↗

PubMed1996

Biochemical relationship between urine composition and urinary stone formation in stone forming patients.

The precise relationship between urine composition and stone formation has not yet been completely understood. The object of this work is to study some constituents of the urine in stone formers and normal subjects in a trial to correlate stone formation with urine composition. Urinary levels of oxalic acid, uric acid and phosphate were elevated in oxalate, urate and phosphate stone formers, respectively, while in the urine of mixed stone formers both oxalic and uric acids were increased. Urinary levels of ascorbic acid, citric acid and mucopolysaccharides in all groups of patients were significantly higher than the corresponding control levels. Although oxalic acid, uric acid and phosphate concentrations were high in their respective stones, the concentrations of these constituents were nearly the same in the mixed stones. Also Ca2+ concentration was higher in stones of oxalate and mixed stone formers than in stones of urate and phosphate formers. Exceptionally, magnesium was high in stones of phosphate stone formers. It is recommended that urinary contents of oxalate, urate and phosphate have to be minimized to overcome stone recurrence.

Adult↗