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PubMed2006

Calcium oxalate urolithiasis in mice lacking anion transporter Slc26a6.

Urolithiasis is one of the most common urologic diseases in industrialized societies. Calcium oxalate is the predominant component in 70-80% of kidney stones, and small changes in urinary oxalate concentration affect the risk of stone formation. SLC26A6 is an anion exchanger expressed on the apical membrane in many epithelial tissues, including kidney and intestine. Among its transport activities, SLC26A6 mediates Cl(-)-oxalate exchange. Here we show that mutant mice lacking Slc26a6 develop a high incidence of calcium oxalate urolithiasis. Slc26a6-null mice have significant hyperoxaluria and elevation in plasma oxalate concentration that is greatly attenuated by dietary oxalate restriction. In vitro flux studies indicated that mice lacking Slc26a6 have a defect in intestinal oxalate secretion resulting in enhanced net absorption of oxalate. We conclude that the anion exchanger SLC26A6 has a major constitutive role in limiting net intestinal absorption of oxalate, thereby preventing hyperoxaluria and calcium oxalate urolithiasis.

Animals↗
PubMed2003

Levels of retinol and retinyl esters in plasma and urine of dogs with urolithiasis.

Vitamin A (VA) deficiency and Tamm-Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol-binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone-forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.

Animals↗
PubMed2001

The association of androgen- and oestrogen-receptor gene polymorphisms with urolithiasis in men.

OBJECTIVE: To evaluate the association of urolithiasis with polymorphic microsatellite (encoding cytosine, adenine, and guanine, CAG) repeats in the exon 1 region of the androgen receptor (AR) gene and thymine/adenine (TA) repeats in the oestrogen receptor (ER). PATIENTS AND METHODS: Patients with urolithiasis (149) and a group of normal controls (102) were examined and compared. The CAG repeats of the AR gene and TA repeats of the ER gene were detected by polymerase chain reaction. The CAG repeats ranged from 171 bp (10 CAG repeats with 141 bp of amplified flanking sequences) to 270 bp (43 CAG repeats). The TA repeats ranged from 160 bp to 194 bp. Associations between calcium oxalate stone disease and the CAG repeats in AR gene and TA repeats in ER gene were then evaluated. The results were classified according to sex and peaks in allelic frequency distribution. RESULTS: There was a significant difference between the male stone patients and the normal controls in the distribution of CAG repeats in the AR gene. Both groups showed a high percentage of 21-repeats in the allelic distribution, at 17 (16%) and 20 (37%) in stone patients and normal controls, respectively. The results indicate that 21-CAG repeats might be related to a lower risk of stone formation in men (P < 0.05). In the ER gene, the peak allelic distribution of TA repeats was 14, showing a significant difference between male stone patients and the normal control subjects (P < 0.01). There were no statistical differences between female stone patients and the control subjects in either the AR or the ER gene. CONCLUSION: Urolithiasis among men appears to be associated with AR gene CAG repeat and ER gene TA repeat polymorphisms, whereas there was no significant association among female stone patients. These sex hormone receptors seem to be related to the higher incidence of stone formation among men.

Adult↗
PubMed1998

Fracture risk among patients with urolithiasis: a population-based cohort study.

In a population-based retrospective cohort study, 624 Rochester, Minnesota residents with an initial symptomatic episode of urolithiasis in 1950 to 1974 were followed for 11,909 person-years for subsequent age-related fractures. During this period of observation, the number of patients with a first vertebral fracture was over four times the number expected on the basis of vertebral fracture incidence rates in the general population of Rochester [standardized morbidity ratio (SMR), 4.3; 95% confidence interval, 3.4 to 5.3]. The risk of vertebral fracture was elevated among men as well as women, and was associated with increasing age and with the use of corticosteroids for more than six months. However, vertebral fracture risk was increased nearly fourfold (SMR 3.9; 95% confidence interval, 3.0 to 4.9) among the urolithiasis patients without such exposure, which suggests that corticosteroids do not completely account for the association with vertebral fractures. There was no increase in the risk of hip, pelvis, proximal humerus or distal forearm fractures in this cohort of patients, and their survival was not impaired. Additional studies are needed to define the pathophysiology of vertebral fractures among patients with urolithiasis.

Adolescent↗
PubMed2001

Felbamate urolithiasis.

PURPOSE: To report a case of felbamate (FBM) urolithiasis. METHODS: Urographic imaging [sonography, abdominal computed tomography (CT), intravenous pyelogram, voiding cystourethrogram] and urologic procedures (cystoscopy with lithotripsy, ureteral stent) to define and capture the stones. Stone identification was by infrared spectroscopy and gas chromatography/mass spectrometry. RESULTS: A 15-year-old boy had painful hematuria, bilateral ureteral obstruction, and urinary retention. Kidney, bladder, and ureteral stones were found, and ureteral stent placement was required to relieve obstruction. The stone material was identified as FBM by chemical analysis. Stone formation ceased with discontinuation of FBM. CONCLUSIONS: FBM urolithiasis can occur, and possible contributory factors include high felbamate dosage, drug polypharmacy, and risk factors for forming stones of other types. FBM urolithiasis may be heralded by crystalluria.

Adolescent↗
PubMed2005

Absorptive hyperoxaluria leads to an increased risk for urolithiasis or nephrocalcinosis in cystic fibrosis.

BACKGROUND: Hyperoxaluria has been incriminated to account for the increased incidence of urolithiasis or nephrocalcinosis in patients with cystic fibrosis (CF). Hyperoxaluria presumably is caused by fat malabsorption and the absence of such intestinal oxalate-degrading bacteria as Oxalobacter formigenes. To better elucidate its pathophysiological characteristics, we prospectively studied patients with CF by determining these parameters and performing renal ultrasonography twice yearly. METHODS: In addition to routine tests in urine (lithogenic and stone-inhibitory substances), the presence of O formigenes was tested in stool, plasma oxalate was measured, and a [13C2]oxalate absorption test was performed in 37 patients with CF aged 5 to 37 years (15 females, 22 males) who were constantly hyperoxaluric before the study. RESULTS: Hyperoxaluria (oxalate, 46 to 141 mg/1.73 m2/24 h [0.51 to 1.57 mmol/1.73 m2/24 h]; normal, < 45 mg/1.73 m2/24 h [< 0.5 mmol/1.73 m2/24 h]) was now found in 24 patients (64.8%). Plasma oxalate levels were elevated in 6 patients (7.92 to 19.5 micromol/L; normal, 6.3 +/- 1.1 micromol/L). Oxalobacter species were detected in only 1 patient. Intestinal oxalate absorption was elevated (11.4% to 28.5%; normal, < 10%) in 23 patients. Hypocitraturia was present in 17 patients (citrate, 0.35 to 2.8 g/1.73 m2/24 h [0.2 to 1.1 mmol/1.73 m2/24 h]; normal female, > 2.8 mg/1.73 m2/24 h [> 1.6 mmol/1.73 m2/24 h]; male, > 3.3 mg/1.73 m2/24 h [> 1.9 mmol/1.73 m2/24 h]). Urine calcium oxalate saturation was elevated in 17 patients (5.62 to 28.9 relative units; normal female, < 5.5 relative units; male, < 6.3 relative units). In 16% of patients, urolithiasis (n = 2) or nephrocalcinosis (n = 4) was diagnosed ultrasonographically. CONCLUSION: Absorptive hyperoxaluria and hypocitraturia are the main culprits for the increased incidence of urolithiasis and nephrocalcinosis in patients with CF. We advocate high fluid intake, low-oxalate/high-calcium diet, and alkali citrate medication, if necessary. Additional studies are necessary to determine the influence of Oxalobacter species or other oxalate-degrading bacteria on oxalate handling in patients with CF.

Adolescent↗
PubMed1985

Childhood urolithiasis in Iran: a comparative study on the calculi composition of 121 cases.

Within 12 years, 165 cases of urolithiasis were observed at the Children's University Hospital of Teheran. The incidence of urolithiasis amounts to 1 case in 300 paediatric hospitalizations. 160 calculi from 121 children were analysed by various methods: semiquantitative chemical analysis (Mercognost), x-ray diffraction, polarising microscopy on thin sections. In about 25% of the cases metabolic disorders or malformations were found responsible for urolithiasis. In 100 cases, stone formation was attributed to the upper and in 21 cases to the lower urinary tract. Calcium oxalates are the most frequent constituents, followed by ammonium acid urate. The core of the stones in the upper tract was mostly composed of calcium oxalate. Ammonium acid urate was the second important core component, but occurred especially enriched in the lower urinary tract. On the basis of these and literature data, the lack of ammonium acid urate in juvenile stones in Europe and the USA seems surprising. Thus, it must be assumed therefore, that ammonium acid urate is a key to understanding the formation of endemic calculi. The cases studied support that with increasing standard of living, the incidence of bladder stones decreases.

Adolescent↗
PubMed2003

Pediatric urolithiasis--evaluation of risk factors in 95 children.

OBJECTIVE: Pediatric urolithiasis is a rarely encountered pathology, except in endemic areas such as Turkey. As a recurrent pathology which may reveal functional as well and morphologic changes in the urinary tract, metabolic and environmental factors, in addition to urogenital abnormalities, should be evaluated thoroughly in each patient. In this prospective study, the patient and family histories of 95 children with stone disease were evaluated, together with serum and urine risk factors. MATERIAL AND METHODS: Between 1996 and 2001, 95 children (25 females, 70 males; mean age 7.3 years; age range 0.6-15 years) referred to our department with urolithiasis were evaluated. All patients were investigated with respect to stone localization, associated abnormalities, urinary tract infection (UTI), positive family history and serum and urine risk factors. In addition to standard risk factors (hypocitraturia, hypercalciuria, hyperoxaluria, hyperuricosuria, hypomagnesuria), diet and 24-h urine volume were also assessed in all children. Children with cystinuria were excluded from the study. RESULTS: Stone size ranged from 0.3 to 3.3 cm, with an average value of 2.0 cm. The localization of the stones was classified as unilateral single stone in 37 patients, multiple unilateral stones in six and bilateral multiple stones in 27. Hypocitraturia was the commonest risk factor detected in our patients. A positive family history was present in 51 cases (54%). In addition, UTI was present in 59 cases (62%) and 67 cases had a previous history of recurrent UTI. Associated urogenital abnormality was detected in nine cases (9.4%). There were significant correlations between stone size and urinary citrate excretion (p < 0.05) and between the presence of UTI and urinary phosphate excretion (r = 0.59, p = 0.047). Treatments used were open surgery in seven (7.3%) cases, extracorporeal shock-wave lithotripsy in 39 (41%) and endoscopic surgery in 20 (21%). Following these procedures, 39 (41%) patients were completely stone-free, 11 (11%) had residual stones (<5 mm in diameter) and 12 (14.8%) passed the stone(s) spontaneously. During follow-up, regrowth was seen in four (4.2%) patients and stone recurrence was noted in a further four (4.2%). CONCLUSIONS: In addition to stone removal, treatment of pediatric urolithiasis requires a thorough metabolic and environmental evaluation of all patients on an individual basis. Obstructive pathologies have to be corrected immediately and apparent metabolic abnormalities should also be treated. Children with a positive family history should be followed carefully with respect to stone recurrence. Urine volume increases in parallel with body mass index and medical therapeutic agents which increase urine citrate levels should be encouraged.

Adolescent↗
PubMed2004

Urolithiasis associated with indinavir in a patient with spinal cord injury.

OBJECTIVE: To report a case of indinavir-induced urolithiasis, and the greater risk of this occurrence in individuals with spinal cord injury (SCI) who require fluid restriction for an intermittent catheterization program (ICP). METHODS: Case report. RESULTS: A 38-year-old man with a T4 ASIA A SCI (according to the American Spinal Injury Association classification scale) and human immunodeficiency virus (HIV) infection was using an ICP and taking indinavir (a protease inhibitor) as part of his antiviral regimen. Cystoscopy was performed to rule out recurrent urethral condylomata. He was found to have a bladder stone measuring 0.5 cm x 0.5 cm x 0.3 cm, which, on analysis, was composed of indinavir (100% exterior, 90% interior). The bladder stone was removed under direct visualization. The plain abdominal radiograph did not reveal any stones. CONCLUSION: Indinavir is a frequently used drug for the treatment of HIV that has the potential to induce urinary lithiasis. This is particularly problematic for individuals with SCI who are on fluid restriction and an ICP. Therefore, cystoscopy and monitoring for indinavir-induced urolithiasis should be undertaken in individuals with SCI who are taking indinavir. Considerations include switching to a different protease inhibitor or choosing an entirely new HIV drug cocktail with less potential for urolithiasis.

Adult↗
PubMed2002

Current management of urolithiasis: progress or regress?

PURPOSE: To assess the impact of the development of less powerful second- and third-generation shockwave lithotripters on surgical stone therapy in light of recent advances in ureteroscopy and laser lithotripsy. As such, we sought to identify current trends in the treatment of stone disease, both at our university medical center and nationally, and to contrast them with the corresponding data from 1990. PATIENTS AND METHODS: All urolithiasis procedures (ureteroscopy, SWL, open surgery, and percutaneous stone removal) performed in 1998 were compared with all urolithiasis procedures performed 8 years earlier (1990) at a single institution (Washington University, St. Louis). In addition, Medicare data for each year from 1988 through 2000 were collected from the Health Care Financing Administration to assess the national trends for open stone surgery, ureteroscopic stone removal, SWL, and percutaneous nephrolithotomy. RESULTS: At Washington University, the number of percutaneous stone removals remained stable; however, the overall number of ureteroscopies increased by 53%, while the number of SWLs, decreased by 15%. The Medicare data likewise reflect a marked decrease in open stone surgery and a marked increase in ureteroscopic stone surgery with a slight increase in SWL. Utilization of percutaneous nephrolithotomy remained unchanged. CONCLUSIONS: We believe this trend toward ureteroscopy is attributable to several factors: improved, smaller rigid and flexible ureteroscopes; the availability of more effective intracorporeal lithotripters (e.g., pneumatic and holmium laser), and the lack of development of lower cost, more effective SWL. This is an unfortunate trend, as we are moving away from the noninvasive treatment that was the hallmark of urolithiasis therapy at the beginning of the last decade toward more invasive endoscopic therapy. Increased research efforts in SWL technology are sorely needed.

Female↗
PubMed1995

Funding for urolithiasis research: progress and strategies for future NIH support.

A review of the National Institutes of Health funding history for urolithiasis shows that support has increased from about $3 million in 1990 to about $4.7 million in 1993 and to an estimated $5.1 million in 1994. The award of large project grants accounts for the increase: individual research project grant funding (R01-type grants) has not increased. The overall funding for urologic research supported by the National Institute of Diabetes and Digestive and Kidney Diseases has more than doubled in this same period, with most of the increase attributable to the award of individual research grants. Although there has been a significant number of urolithiasis research grant applications submitted in this time period, the percent of successful (funded) applications continues to lag behind the number in other urology-related areas. Strategies for improving the award rate for urolithiasis-related research grant applications are reviewed.

Forecasting↗
PubMed1999

Is there a role for uric acid in an animal model of calcium phosphate nephrocalcinosis and calcium phosphate crystallization in urine of patients with idiopathic calcium urolithiasis? An orientational study.

Uric acid (UA), a waste product of purine metabolism, may be involved in calcium phosphate crystallization and deposition. Rats, which develop nephrocalcinosis on high-fat or magnesium-deficient diets, and patients with idiopathic calcium urolithiasis have hyperproteinuria, especially of nonalbumin protein, and a shift toward elevated serum UA. In rats, an increase in UA precursors and renal UA suggests hypoxemia, which stimulates xanthine oxidase. In patients, a primary increase in renal xanthine oxidase would explain the low urine UA in the presence of an elevated serum concentration. For calcium phosphate deposition (rats) or incorporation into stones (humans) to occur, a crucial factor may be xanthine oxidase-mediated overproduction of free radical species and subsequent tissue damage. Another factor may be whether sufficient UA is synthesized to neutralize these free radicals. Allopurinol use, which inhibits xanthine oxidase and has long been favored for the treatment of idiopathic calcium urolithiasis, may not prevent stones, because it also diminishes the availability of UA. An investigation of the factors that control serum UA homeostasis may be rewarding in research into the etiology of idiopathic calcium urolithiasis.

Animals↗
PubMed2003

Slc7a9-deficient mice develop cystinuria non-I and cystine urolithiasis.

Cystinuria is a common recessive disorder of renal reabsorption of cystine and dibasic amino acids that results in urolithiasis of cystine. Cystinuria is caused by defects in the amino acid transport system b0,+ (i.e. the rBAT/b0,+AT heteromeric complex). Mutations in SLC3A1, encoding rBAT, cause cystinuria type A, characterized by a silent phenotype in heterozygotes (phenotype I). Mutations in SLC7A9, encoding b0,+AT, cause cystinuria type B, in which heterozygotes in most cases hyperexcrete cystine and dibasic amino acids (phenotype non-I). To facilitate in vivo investigation of b0,+AT in cystinuria, Slc7a9 knockout mice have been generated. Expression of b0,+AT protein is completely abolished in the kidney of Slc7a9-/- mice ('Stones'). In contrast, Stones expressed significant amounts of rBAT protein, which is covalently linked to unidentified light subunit(s). Stones mice present a dramatic hyperexcretion of cystine and dibasic amino acids, while Slc7a9+/- mice show moderate but significant hyperexcretion of these amino acids (phenotype non-I). Forty-two per cent of Stones mice develop cystine calculi in the urinary system. Calculi develop during the first month of life and grow throughout the life span of the animals. Histopathology in kidney reveals typical changes for urolithiasis (tubular and pelvic dilatation, tubular necrosis, tubular hyaline droplets and chronic interstitial nephritis). The fact that some Stones mice, generated in a mixed genetic background, develop cystine calculi from an early age, while others do not develop them in their first year of life, suggests the involvement of modifier genes in the lithiasis phenotype. Thus, Stones provide a valid model of cystinuria which can be used in the study of genetic, pharmacological and environmental factors involved in cystine urolithiasis.

Amino Acid Transport Systems, Basic↗
PubMed1997

Urolithiasis in the exstrophy-epispadias complex.

PURPOSE: We sought to determine the incidence of urolithiasis in patients with the exstrophy-epispadias complex, associated risk factors and guidelines for the proper clinical management of this problem. MATERIALS AND METHODS: We retrospectively reviewed the chart and x-rays of 530 patients with the exstrophy-epispadias complex treated at our institution. RESULTS: Stones formed in 77 of the 530 patients (15%), including 16% of those with classic exstrophy, 25% of those with cloacal exstrophy and 3% of those with epispadias. White and male individuals were most commonly affected. Most calculi formed in the bladder, whether native or augmented by enterocystoplasty. Standard techniques were successful for stone removal. Most calculi consisted of calcium apatite, calcium oxalate monohydrate or magnesium ammonium phosphate, usually in combination with at least 1 other element. The risk of stone formation was associated with augmentation cystoplasty (p < 0.001) and a bladder neck procedure to increase outlet resistance (p < 0.001). Other risk factors included urinary tract infection, foreign bodies, vesicoureteral reflux and urinary stasis but not acidosis or immobilization. Stones recurred in 30 patients (39%), including equal numbers of those treated with open and closed techniques, and recurrence was associated with urinary tract infection or struvite composition (p < 0.05). Serum calcium abnormalities were not present in any patient, including those with metabolic acidosis or prolonged immobilization. Urinary chemistry studies were incomplete or unavailable. CONCLUSIONS: These data suggest that urolithiasis in the exstrophy-epispadias complex is related to risk factors associated with surgical reconstruction of this condition. The role of metabolic abnormalities that may predispose to urolithiasis is unknown but under investigation. Standard treatment is effective but stone recurrence remains a significant problem. Urine chemistry data may provide information to help minimize stone development in this patient population.

Abnormalities, Multiple↗
PubMed2001

Adequacy of a single stone risk analysis in the medical evaluation of urolithiasis.

PURPOSE: We tested the hypothesis that a single 24-hour urine sample for stone risk analysis would be sufficient for the simplified medical evaluation of urolithiasis. MATERIALS AND METHODS: We retrospectively analyzed stone risk profile data on 24-hour urine samples obtained during random and restricted diets in 225 patients with recurrent urolithiasis. RESULTS: In 2 random samples we noted no significant difference in urinary calcium, oxalate, uric acid, citrate, pH, total volume, sodium, potassium, sulfate or phosphorus. For these risk factors there was a highly significant positive correlation in the 2 random samples (r > or = 0.68, p <0.0003) and the value of each was abnormal or normal in at least 81% of patients. Urinary magnesium and ammonium were significantly lower in random sample 2 than 1, the former by 4%. After calcium, sodium and oxalate dietary restriction mean urinary calcium and sodium plus or minus standard deviation decreased significantly by 25% from 251 +/- 125 to 187 +/- 98 mg. daily and by 38% from 183 +/- 87 to 113 +/- 57 mEq. daily, respectively. Other risk factors had a slight or no significant change. Correcting random urinary calcium for the excessive urinary excretion of sodium brought urinary calcium to 210 +/- 108 mg. daily, similar to the value on the restricted diet. CONCLUSIONS: The reproducibility of urinary stone risk factors is satisfactory in repeat urine samples. A single stone risk analysis is sufficient for the simplified medical evaluation of urolithiasis.

Adolescent↗
PubMed2002

Hematuria due to urolithiasis in a child with chronic immune thrombocytopenic purpura.

Hematuria is an uncommon manifestation of chronic immune thrombocytopenic purpura. The occurrence of urolithiasis in children with chronic immune thrombocytopenic purpura has not been described. We report a case of hematuria due to urolithiasis in an 8-year-old boy with chronic immune thrombocytopenic purpura. This child, who had a history of immune thrombocytopenic purpura of 1 year's duration, presented to the emergency department with gross hematuria. The cause of hematuria was initially attributed to his primary disease process. A careful history, examination, and pertinent investigations revealed that the hematuria was secondary to urolithiasis. This report highlights the need to keep an open mind and to search for specific causes of bleeding, even in children with known bleeding disorders.

Child↗
PubMed2001

Economics of urolithiasis: cost-effectiveness of therapies.

The cost of treating urolithiasis with extracorporeal shockwave lithotripsy and endoscopic surgery continues to be a significant burden on a nation's healthcare economy. Cost-effectiveness evaluations of various medical and surgical treatment options for urolithiasis is a practical method of developing rational allocation strategies for limited economic resources. In this review, the cost-effectiveness of shockwave lithotripsy and that of endoscopic surgery in the management of kidney and ureteral stones are compared. This is followed by a discussion of the cost of the medical management of urolithiasis in comparison with repeated surgical treatment.

Cost-Benefit Analysis↗
PubMed2003

Identifying patients who are suitable for stentless ureteroscopy following treatment of urolithiasis.

PURPOSE: Foregoing ureteral stents following ureteroscopy for urinary calculi is an evolving practice. Randomized trials support stent omission in select cases though generalizability is unclear and criteria for stentless ureteroscopy are unknown. Therefore, we sought to identify significant clinical characteristics affecting postoperative morbidity in unstented patients to provide a context for future randomized trials. MATERIALS AND METHODS: Of 837 ureteroscopic procedures for urolithiasis performed at our institution from January 1997 through January 2002 a ureteral stent was not placed in 226 (32%). Among these patients 47 had no stone at the time of the procedure leaving 219 (26%) who were treated for urinary calculus disease. Multivariate logistic regression was used to determine the association of 24 variables with postoperative morbidity. RESULTS: Of the 219 patients treated with ureteroscopy 39 (18%) had a postoperative complication, which was obstructive in 26 (12%), infectious in 10 (5%), and related to patient co-morbidity in 3 (1%). Factors associated with postoperative morbidity included renal pelvic location (p = 0.02), lithotripsy (p = 0.03), bilateral procedure (p = 0.07), history of urolithiasis (p <0.0001), diabetes mellitus (p = 0.06), recent/recurrent infection (p <0.0001), operative time 45 minutes or greater (p = 0.07), operative time 45 minutes or greater plus lithotripsy (p = 0.0004), operative time 45 minutes or greater plus ureteral dilation (p = 0.07) and bilateral stentless procedure (p = 0.005). CONCLUSIONS: Multiple patient and operative factors may predispose a patient to postoperative morbidity after a stentless procedure. Future trials should prospectively validate the role of these factors in either promoting (e.g., history of urolithiasis) or preventing (e.g., preoperative stent) a postoperative complication in the setting of stentless ureteroscopy.

Adult↗