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PubMed2004

Usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection.

PURPOSE: To determine the usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection. MATERIAL AND METHODS: Sixty radiographs with a single urinary calculus less than 5 mm in the long diameter (15 in the kidney; 15 in the proximal ureter; 15 in the mid-ureter, 15 in the distal ureter) and 15 radiographs without calculi were evaluated. Four readers blinded to the presence or absence of urinary calculi on each radiograph reviewed the radiographs in the conventional display, reversed display, and combination of conventional and reversed displays at 1-week intervals. All images were evaluated in random order and the presence or absence of urinary calculi was interpreted using the confidence score from 1 to 5. RESULTS: Multireader analysis for calculi in all locations showed a greater area under the receiver operating curve for combination of the two displays (0.764) than for the conventional display alone (0.655) (P=0.031). In the single-reader analysis for calculi in all locations, the third reader showed a greater area under the receiver operating curve for the reversed display (0.784) than for the conventional display (0.622) (P=0.027). Multireader analysis of the calculi in the kidney showed a greater area under the receiver operating curve for combination of the two displays (0.824) than for the conventional display alone (0.703) (P=0.043). CONCLUSION: The reversed display of soft-copy abdominal radiographs may be useful for urinary calculi detection.

Area Under Curve↗
PubMed1999

Piezoelectric shockwave lithotripsy of urinary calculi: comparative study of stone depth in kidney and ureter treatments.

PURPOSE: The aim of this prospective study was to assess the relation between stone depth and the efficiency of piezoelectric extracorporeal shockwave lithotripsy (SWL). PATIENTS AND METHODS: A total of 150 patients presenting with 25 pelvic, 75 caliceal, and 25 upper and 25 lower ureteral calculi were treated using the EDAP LT02 lithotripter. All of the stones were easy to localize with sonographic and radiographic systems, and their largest diameter ranged from 4 to 25 mm (mean 8.5 mm). Renal and upper ureteral calculi were treated with the patient in the supine position and lower ureteral stones in prone position. On the basis of a meticulous stone localization and focusing, depth measurements were carried out under real-time ultrasonic guidance, the minimal distance between the cutaneous plane and the focal point being recorded only for definitely localized calculi. RESULTS: Ureteral calculi were significantly deeper than renal stones (p < 0.0001), but the distance from the cutaneous plane was statistically similar for upper and lower ureteral calculi. Stone depth was statistically affected by body mass index (BMI), patients with a BMI >25 having significantly deeper renal and ureteral calculi than subjects with a BMI < or =25 (p < 0.00001 and 0.01, respectively). Renal stones resisting SWL were significantly deeper than successfully treated calculi (p < 0.03). At the level of the ureter, the success rate after one SWL session was 85% for stones with a depth < or =110 mm and 57% for deeper stones, the difference being significant (p < 0.05). CONCLUSION: Stone depth has a significant influence on treatment outcome after piezoelectric SWL for both renal and ureteral calculi. We recommend particular attention be given to corpulent patients presenting with ureteral stones.

Adult↗
PubMed1982

Role of fluoride in formation of urinary calculi: studies in rats.

The effect of fluoride on urinary calculi formation in young rats was investigated. Two studies, in which rats received diets that included either higher calcium (9 g/kg diet) or normal calcium (5 g/kg diet), were conducted At each level of calcium, one group of rats received a high level of fluoride and another a low level of fluoride in the diet. Rats ingesting high fluoride diets exhibited a higher incidence of crystalluria and bladder stones compared with those receiving low fluoride diets. However, compared with higher calcium diets, normal calcium diets delayed the appearance of crystalluria and produced smaller calculi. Calcium and oxalate were the major components of the calculi. Calculi of rats fed the higher calcium and high fluoride diet contained relatively less protein and more calcium compared with calculi formed in rats ingesting the higher calcium and low fluoride diet. The concentration of fluoride in calculi from rats fed high fluoride diets was significantly higher than that of calculi from rats fed low fluoride diets. A significant positive correlation between calcium and fluoride concentration of calculi was observed in rats fed the higher calcium diet only. These studies indicate that ingestion of excess fluoride facilities calcium oxalate crystalluria and promotes the formation of bladder stones in rats, under the experimental conditions used.

Animals↗
PubMed1993

In situ ESWL for ureteric calculi: the optimum treatment?

In situ ESWL for ureteric calculi is associated with good stone clearance rates but is it without significant morbidity? A review of 189 patients with single ureteric calculi (150 upper ureter, 39 lower ureter calculi) revealed an 89% stone clearance for upper ureteral calculi and 80% stone clearance for lower ureteral calculi. However 11% of patients with upper ureteral calculi and 20% of patients with lower ureteral calculi required additional intervention for complications or failed treatment. In situ ESWL may not be the optimum therapy for all ureteric calculi especially those in the lower ureter.

Adolescent↗
PubMed2002

Non-contrast thin-section helical CT of urinary tract calculi in children.

BACKGROUND: Non-contrast thin-section helical CT has gained acceptance for the diagnosis of urinary tract calculi in adults, but experience with the technique in children is limited. PURPOSE: To evaluate the utility of non-contrast thin section helical CT for the diagnosis of urinary tract calculi in children. MATERIALS AND METHODS: Radiology databases at three pediatric institutions were searched to identify all pediatric patients evaluated by "renal stone" protocol CT scans (no oral or intravenous contrast, scans covering the entire urinary tract obtained in helical mode with narrow collimation (< 5 mm)). CT scans were reviewed for the primary finding of urinary tract calculi, for secondary signs of acute urinary tract obstruction and for evidence of alternative diagnoses. Medical records were reviewed to determine clinical presentation and to confirm the eventual diagnosis. RESULTS: One hundred thirty-seven scans of 113 children (mean age: 11.2 years) were studied. Thirty-eight of 94 examinations (40%) performed on 82 children for acute pain and/or hematuria showed ureteral calculi. Alternative diagnoses were suggested by CT on 16 scans (17%). Twenty-eight scans were performed on 10 asymptomatic children with known calculus disease confirming renal stone burden on 21 scans (75%) and persistent ureteral calculi on 6 scans (21%). Upper tract calculi were demonstrated on 10 of 15 scans (67%) performed to evaluate for calculi in patients with known non-calculus genitourinary tract abnormalities. CONCLUSIONS: Non-contrast thin section helical CT is a useful method to diagnose urinary tract calculi in children. Radiation dose in this retrospective study may exceed the lowest possible radiation dose for diagnostic accuracy. Further research is needed to optimize CT imaging parameters, while maintaining diagnostic accuracy and minimizing radiation dose.

Adolescent↗
PubMed2004

Helical CT evaluation of the chemical composition of urinary tract calculi with a discriminant analysis of CT-attenuation values and density.

The aim of this study was to evaluate the efficacy of helical CT using a combination of CT-attenuation values and visual assessment of stone density as well as discriminant linear analysis to predict the chemical composition of urinary calculi. One hundred human urinary calculi were obtained from a stone-analysis laboratory and placed in 20 excised pig kidneys. They were scanned at 80, 120 and 140 kV with 3-mm collimation. Average, highest and lowest CT-attenuation values and CT variability were recorded. The internal calculus structure was assessed using a wide window setting, and visual assessment of stone density was recorded. A stepwise discriminant linear analysis was performed. The following three variables were discriminant: highest CT-attenuation value, visual density, and highest CT-attenuation value/area ratio, all at 80 kV. The probability of correctly classifying stone composition with these three variables was 0.64, ranging from 0.54 for mixed calculi to 0.69 for pure calculi. The probabilities of correctly classifying calculus composition were: 0.91 for calcium oxalate monohydrate and brushite, 0.89 for cystine, 0.85 for uric acid, 0.11 for calcium oxalate dihydrate, 0.10 for hydroxyapatite, and 0.07 for struvite calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, 81% of the calculi were correctly classified. Assessment at 80 kV of the highest CT-attenuation value, visual density and the highest CT-attenuation value/area ratio accurately predicts the chemical composition of 64-81% of urinary calculi. When the first two ranks of highest probability for the accurate classification of each calculus type were taken into account, all cystine, calcium oxalate monohydrate and brushite calculi were correctly classified.

Animals↗
PubMed2006

[Drug-induced renal calculi].

Drug-induced renal calculi represent 1-2% of all renal calculi. They include two categories: those resulting from the urinary crystallisation of a highly excreted, poorly soluble drug or metabolite, and those due to the metabolic effects of a drug. Indinavir, used in HIV-infected patients, sulfonamides, especially sulfadiazine, and triamterene, which is less prescribed today, are the most frequent. Besides these drugs, about twenty other molecules, among them silicate-containing drugs and some antibiotics have been reported in patients receiving high doses or long-term treatments. Calculi analysis by physical methods such as infrared spectroscopy or x-ray diffraction can demonstrate the presence of the drug or its metabolites inside the calculi. In those calculi due to the metabolic effects of a drug, diagnosis relies on both stone analysis and clinical inquiry. Incidence of such calculi is probably underestimated, especially those due to calcium/vitamin D supplements or carbonic anhydrase inhibitors. Drug-induced calculi occur more often during high-dose or long term treatments, but there are also patient-related risk factors in relation to urine pH, urine output and other parameters, which can provide a basis for preventive treatment of such calculi. A better knowledge of these lithogenic complications of treatments and of solubility characteristics of drugs should reduce the incidence of drug-induced nephrolithiasis, especially in patients with identified risk factors.

HIV Protease Inhibitors↗
PubMed2006

Changing composition of renal calculi in patients with neurogenic bladder.

PURPOSE: Renal calculi are a significant source of morbidity for patients with neurogenic bladder. Calculi from patients with NB have traditionally been composed primarily of struvite and carbonate apatite secondary to chronic urea-splitting bacteriuria. In the current era there have been great improvements in the urological rehabilitation of patients with NB. We defined the composition of renal calculi in a contemporary cohort of patients with NB due to spinal cord injury or myelomeningocele who underwent percutaneous nephrolithotomy. MATERIALS AND METHODS: We performed a retrospective evaluation of all patients with NB due to SCI or MM who underwent PNL between January 2002 and January 2005. RESULTS: A total of 32 patients with NB (14 with SCI, 18 with MM) underwent PNL in this period. Stones were infectious in etiology in 37.5% (12 struvite/carbonate apatite) and metabolic in 62.5% (1 uric acid, 2 calcium oxalate monohydrate, 2 brushite, 6 hydroxyapatite, 9 mixed hydroxyapatite/calcium oxalate). All patients with struvite calculi were infected with urea-splitting bacteria on preoperative urine culture. CONCLUSIONS: Patients with neurogenic bladder are traditionally thought to harbor infection related calculi. These data demonstrate that many contemporary patients will be found to have calculi of a metabolic etiology. Although patients with NB still have renal calculi, advances in urological treatment may have affected the composition of their calculi, as metabolic stones are becoming more commonly identified. When metabolic components are identified, stone activity may be attenuated with appropriate metabolic evaluation, pharmacological therapies and dietary modifications.

Adolescent↗
PubMed1994

Inhibition of calculi fragment growth by metal-bisphosphonate complexes demonstrated with a new assay measuring the surface activity of urolithiasis inhibitors.

To evaluate compounds for the long-term inhibition of urinary calculi growth, we applied a newly developed in vitro assay to various metal-ligand complexes. The new experimental model--the preadsorbed calculi growth assay--was based upon the initiation of crystal growth in a metastable solution of calcium and oxalate with uniform granules derived from human renal calculi. Potential inhibitors were first absorbed onto the surface of the calculi granules, following which the loss of calcium from the seeded metastable solution was monitored as the indicator of calcium oxalate deposition. This assay allowed participation in the reaction by any matrix components present in the human calculi granules and limited the effect of the inhibitors to the calculi surface. Some complexes of metal ions with bisphosphonates had strong inhibitory effects, as opposed to citrate complexes which had minimal effect in this assay. Tin was the most potent metal ion, and pamidronate was the most potent bisphosphonate; together they slowed the growth of calculi granules to 9% of control. The inhibition by Tin-bisphosphonate complexes persisted despite a week of continual rinsing with a solution of sodium chloride and calcium. If the metal-bisphosphonate complexes are active in vivo as well, they might be considered for prophylaxis of calcium oxalate calculi or the prevention of regrowth of residual fragments following lithotripsy.

Calcium↗
PubMed1992

Electromagnetic extracorporeal shock wave lithotripsy for calculi in horseshoe kidneys.

Between June 1987 and January 1991, 11 renal units in 10 patients with horseshoe kidneys were managed by electromagnetic extracorporeal shock wave lithotripsy (ESWL) monotherapy with a Siemens Lithostar. A total of 33 calculi was treated in 42 sessions. All treatments were performed without anesthesia and on an outpatient basis. All calculi could be targeted by standard installation techniques. The maximum number of shock waves per session was 4,000, which implies per stone an average of 1.3 sessions and an average of 4,903 shock waves (range 1,800 to 9,000) at a mean energy setting of 17.8 kv. Complete disintegration or fragmentation into spontaneously passable particles was achieved in 27 calculi, for a success rate of 83% when considering the results in regard to the individual stone locations. Per renal unit, an average of 3 calculi were targeted and after an average of 3.8 sessions 6 units became stone-free. Horseshoe kidneys, when calculous, contain dispersed and multiple calculi and from these data approximately 1 session per stone must be planned. The number of treatments per renal unit increased in proportion to the number of calculi and to the presence of calculi with low fragility. Of 21 lower pole calculi 18 completely evacuated and this observation has been related to the more medial location of the inferior calices near the ureteropelvic junction. No impaired drainage of fragments was noted to be related to the horseshoe anatomy. Patency of the ureteropelvic anatomy appeared to be the main parameter for the evacuation of fragments. Neither preoperative nor postoperative adjuvant maneuvers have been necessary.

Adult↗
PubMed2001

Comparison of outcomes of ureteroscopy for ureteral calculi located above and below the pelvic brim.

OBJECTIVES: To compare the safety and efficacy of ureteroscopy performed for proximal and distal ureteral calculi in a contemporary cohort. Ureteroscopy has been used most often for distal ureteral calculi. However, advances in endoscopic equipment have facilitated access to the proximal urinary tract and have broadened the indications for ureteroscopy. METHODS: One hundred ninety-one patients underwent rigid and/or flexible ureteroscopy for ureteral calculi at the University of Michigan between January 1, 1997 and September 30, 1999. Only 7 patients with either bilateral calculi or steinstrasse were excluded. The final cohort consisted of 184 patients who underwent ureteroscopy for distal stones (n = 103) or middle/upper ureteral stones (n = 81). RESULTS: Bivariate analyses of pretreatment and perioperative characteristics were used to assess the sample population. The initial success rate for the distal and proximal ureteral calculi was 96% and 78%, respectively (P = 0.0008). After a "second-look" procedure in 4 and 7 patients with distal and proximal calculi, respectively, the success rate improved to 99% and 88%, respectively (P = 0.004). No differences were noted between groups regarding the intraoperative (P = 0.51) or postoperative (P = 0.85) complication rates. Multivariate logistic regression analysis confirmed that larger stone size (odds ratio 1.2, P = 0.0006) and proximal ureteral location (odds ratio 4.8, P = 0.01) are independent predictors of treatment failure. CONCLUSIONS: Ureteroscopic management of proximal and distal ureteral calculi is highly successful, and the difference in success rates has narrowed substantially. Currently, no greater risk is conferred to the patient for endoscopy of more proximal ureteral calculi.

Adult↗
PubMed2001

Flexible ureteroscopy in conjunction with in situ lithotripsy for lower pole calculi.

OBJECTIVES: To demonstrate the efficacy and safety of ureteroscopy as a compromise in treating small and intermediate-size lower pole calculi. The optimal management of lower pole calculi remains controversial. Shock wave lithotripsy is associated with minimal morbidity but with suboptimal stone clearance rates. Conversely, percutaneous nephrostolithotomy has greater morbidity but stone-free rates greater than 90% regardless of size. METHODS: Seventy-two patients underwent ureteroscopy for lower pole calculi 2 cm or less (mean 8.7 mm) during a 3-year period. To minimize confounding, 11 patients with additional calculi at other ipsilateral renal sites and 1 patient with large (2.4 cm each) bilateral calculi were excluded. Two patients with bilateral lower pole calculi and four who required a second procedure were included in the analysis. Thus, the final cohort consisted of 60 patients who underwent 66 procedures. RESULTS: Of patients with follow-up longer than 1 month, 79% were stone free after a single procedure, and this improved to 88% after a second procedure in 4 patients. All 7 patients with follow-up less than 1 month had a reduction in stone burden after successful fragmentation. Overall, 8 patients required an auxiliary procedure. No intraoperative complications, and 7 (11%) postoperative complications occurred. CONCLUSIONS: Ureteroscopy for lower pole calculi is associated with minimal morbidity and stone-free rates comparable to shock wave lithotripsy for smaller stones. The greatest utility of ureteroscopy is in the management of intermediate-size calculi, for which it has substantially higher stone-free rates and lower repeated treatment rates than does shock wave lithotripsy.

Chi-Square Distribution↗
PubMed2004

Endoscopic treatment of bladder calculi in post-renal transplant patients: a 10-year experience.

BACKGROUND AND PURPOSE: Urinary calculus formation following renal transplantation is an uncommon phenomenon. As a result of the growing number of renal transplants performed and the greater graft survival, there has been increased awareness of transplant-related complications, one of which is calculus formation. We report our experience in the management of bladder calculi after renal transplantation. PATIENTS AND METHODS: We retrospectively reviewed the charts of 500 consecutive renal transplant patients from 1992 through 2002 and encountered 7 who had bladder calculi postoperatively. Ureteroneocystostomy had been performed using polyglactic acid suture. Bladder calculi were treated endoscopically by litholapaxy, electrohydraulic lithotripsy (EHL), or holmium:YAG laser lithotripsy. RESULTS: Three calculi were found incidentally at the time of stent removal, and the others were associated with hematuria (43%), urinary tract infection (14%), or irritative voiding symptoms (14%). Eighty-six percent of the calculi were close to the allograft ureteral orifice. CONCLUSION: While various forms of lithotripsy were employed in treating bladder calculi, Hol:YAG laser lithotripsy appeared to be both efficacious and safe. Both EHL and litholapaxy were complicated by mucosal bleeding necessitating Bugbee fulguration. Holmium:YAG laser lithotripsy was not associated with mucosal bleeding, and fulguration was not required near the allograft ureteral orifice. In addition, ureteral stenting is not required. Bladder calculi may form over both absorbable and nonabsorbable suture material, and the ideal suture for the ureteroneocystostomy has yet to be found. Until then, the Hol:YAG laser should be the lithotrite of choice for bladder calculi following renal transplantation.

Adult↗
PubMed1988

Urinary calculi in renal transplant recipients.

UNLABELLED: Urinary calculi are an uncommon complication in renal transplant recipients. During a 15-year period, in 544 cases of kidney transplantation with a functioning allograft for more than 3 months, and a long-term follow-up, we have observed 9 cases (1.7%) of urinary calculi. Calculi occurred in 6 male and 3 female patients, 6 patients were recipients of living related and 3 of cadaveric kidneys. Calculi were diagnosed as early as 3 months and as late as 3.5 years after transplantation, but most were detected within the first year. The location of the calculi was the bladder in 4 cases, the transplant in 3, and indeterminant in 2. Crystallographic analysis of retrieved stones revealed calcium oxalate and/or phosphate in 4 cases, triple phosphate in 2, and uric acid in 1. All patients had one or more stone-predisposing factors, such as obstructive uropathy and recurrent urinary tract infection (4 cases), hyperoxaluria (3), or hypercalciuria (2). During long-term follow-up (mean 60 months), only one patient lost the renal graft, 14.5 years after transplantation, primarily from causes unrelated to urinary calculi. One instance of stone recurrence was noted. IN CONCLUSION: (1) urinary calculi after renal transplantation are relatively uncommon; (2) predisposing factors and crystallographic composition of the calculi are identical in type, but not frequency, to those of nontransplant patients; and (3) with proper medical and surgical management, post-transplant urolithiasis does not appear to affect graft prognosis.

Adult↗
PubMed1975

Morphology of salivary calculi. The distribution of the inorganic component.

Different hypotheses concerning the pathogenesis of salivary calculi have been postulated on the basis of their morphology. In the present study, microradiography of plane-polished ground sections of a number of salivary calculi has shown that the morphology of salivary calculi varies considerably. The commonly accepted concept that salivary calculi emanate from an inorganic nucleus, which then successively grows by the apposition of alternating shells of organic and inorganic substances, could not be established by this study, as the microradiographs show that the distribution of mineral elements varied extensively from one calculus to another. Thus, whereas some calculi exhibited a lamellar structure, others consisted largely of homogeneous, irregular layers of alternatively high and low mineral content. The lamellar structure also showed great variation, extending in some cases over the entire diameter of the calculus. Some calculi lacked the lamination in their peripheral parts whereas, in others, lamination occurred only in the most peripheral zone. The structure of the central portions also showed a varied configuration. The calculi were often built up around one or more mineralized nuclei, often centrally located, while in some cases a mineralized nucleus was lacking. This report discusses some of the significant factors in the great variation in morphological features and therefore also in the pathogenesis of salivary calculi.

Humans↗
PubMed1982

Renal calculi in apparently normal sheep.

The incidence of renal calculi in sheep was determined and the effects of season, sex and difference between left and right kidneys were considered. Examinations for calculi were made by x-ray photography and stereomicroscopy. The seasonal study extended from June 1972 to June 1973. The lowest incidence of calculi, occurred from November to February (25 to 35%) and the highest, in June 1972 (61%) and May 1973 (63%); in other months it generally ranged from 40 to 50%. These differences were highly significant (P less than 0.001). The incidence of calculi greater than 2 mm diameter was 0% and 3% in January and February and, except for 18% in June 1972 values were about 8%. Subepithelial deposits ranged from 2% (April) to 25% (June 1972) about a mean of 11%. Calculi were found most frequently in the middle third of the kidney and near the fornices. Of kidneys with microcalculi (less than 0.05 mm diameter) visual assessment showed 64% contained silica, 29% oxalate, 15% carbonate and 5% material of undetermined nature. Difference in the incidence of calculi between ewes and wethers and between left and right kidneys were not significant and the distribution of calculi within these kidneys was similar to that in the seasonal study. These results are discussed in relation to urinary tract obstruction in grazing sheep and to possible factors affecting the retention in and movement of calculi from the kidney.

Animals↗
PubMed1975

An observation on the composition and recurrence of urinary calculi.

Seven hundred patients with 735 urinary calculi were studied for the compositions of calculi by infrared analysis and for stone recurrence. Of these 700 cases, 422 cases were possible to follow up, and 250 cases have had no further stone; 138 cases experience recurring stones, and 34 cases had multiple stones. The length of follow-up period was 1-19 years averaging 8 years, 8 months. 41.2% of patients with calcium oxalate-calcium phosphate calculi had stones recurrently, and although there was some variation of recurrence rates for patients with various proportions of oxalate to phosphate in the calculi, it was impossible to predict the tendency of recurrence by these proportions. The stone recurrence was noted in 38.6% of patients with magnesium ammonium phosphate calculi, in 38.9% with mixed magnesium ammonium phosphate-calcium oxalate calculi, in 55.6% with uric acid calculi, and in 50% with cystine calculi.

Adolescent↗
PubMed1985

Percutaneous lithotripsy of staghorn calculi.

Eleven cases of staghorn calculi managed by percutaneous lithotripsy were reviewed. Ten of 11 cases were successful, and 70% of the successfully treated patients were discharged free of any renal stones. The percentage of patients discharged with residual stone fragments was higher than those with either percutaneously managed nondendritic calculi or surgically treated staghorn calculi. The complication rate was higher than for nonbranched stones managed percutaneously and was comparable to that for surgically removed dendritic calculi. Hospital stay averaged 18 days, equal to that for staghorn calculi treated by conventional surgical approach, but considerably longer than for nonbranched stones. Overall results more closely approximated those for surgical removal of staghorn calculi than those for percutaneous removal of nonbranched calculi. However, the principal advantage of percutaneous lithotripsy of staghorn calculi over surgical management is the significant reduction in convalescence after discharge from the hospital.

Adult↗