What's New?
2001 American Urological Association Meeting

Risk of Calcium Oxalate Stone Formation with Ascorbic Acid Ingestion

It is believed that ascorbic acid has been thought to increase the stone risk in patients via metabolism to oxalate and acidification of the urine. In patients who ingested 2 grams of ascorbic acid per day resulted in a statistically significant increase in urinary oxalate in normal subjects (20%), and stone formers (33%), but there was no statistical change in the urine pH. It is recommended that ascorbic acid should be limited to less than 2 grams per day in patients who are calcium oxalate stone formers.

Traxer O, Adams-Huet B, Pak CYC, Pearl MS. Risk of Calcium Oxalate Stone Formation with Ascorbic Acid Ingestion. Journal of Urology 165:243A, 2001.

 

Urinary Lithogenic Promoters and Inhibitors During the Three Trimesters of Pregnancy

In this study, it was shown that urinary biochemical components (calcium, phosphate and uric acid) were found to be higher during each trimester of pregnancy compared with non-pregnant and post-menopausal women. In the third trimester of pregnancy, urinary oxalate was significantly elevated while citrate and magnesium were significantly lower when compared to the first trimester. However, there are no reports to date of a higher incidence of stone disease in pregnant women, suggesting that the short duration of pregnancy may not cause stone formation, or that pregnant women excrete other compounds that may protect them from urolithiasis.

Nageswararao C, Sudha C, Sarada B, Satyanarayana U. Urinary Lithogenic Promoters and Inhibitors during the Three Trimesters of Pregnancy. Journal of Urology 165:243A, 2001.

 

Protective Analysis of The Impact of Timing on Metabolic Stone Evaluation for Stone Patients

The timing of evaluation for patients with metabolic stone disease is under debate. Most physicians recommend evaluation when the patient has completed treatment or the patient has become stone-free. In this study, there was a significant increase in urinary citrate levels from initial analysis to delayed analysis. There were no significant changes in urinary volume, calcium or oxalate.

Smith LJ, Kolon TF, Miller OR, Kane CJ. Protective Analysis of The Impact of Timing on Metabolic Stone Evaluation for Stone Patients. Journal of Urology 165:244A, 2001.

 

Metabolic Risk Factors for Stone Formation in Patients with Cystic Fibrosis

Cystic Fibrosis is an autosomal recessive trait, which is characterized by chronic pulmonary disease, insufficient pancreatic and digestive function, abnormally concentrated sweat, and an increase incidence of urolithiasis, and a high risk of stone recurrence. Patients with cystic fibrosis have an increased risk for hyperoxaluria, increased levels of urinary calcium oxalate and decreased urinary citrate levels. The authors recommend that metabolic evaluation is indicated in all patients with cystic fibrosis.

Gatti J, Caplan D, Smith E, Kirsch A. Metabolic Risk Factors for Stone Formation in Patients with Cystic Fibrosis. Journal of Urology 165:244A, 2001.

 

The Etiology of Urolithiasis in HIV Patients

HIV patients demonstrate a variety of stone types and can be attributed to the underlying metabolic abnormalities rather than the use of protease inhibitors. The authors recommend that all HIV patients should undergo a metabolic workup to prevent future stone formation.

Loor MM, Smith ND, Nadler RB. The Etiology of Urolithiasis in HIV Patients. Journal of Urology 165:244A, 2001.

 

Renal Nerves Mediate Renal Vasoconstriction Caused by Shockwave Lithotripsy

It has been shown that shockwave lithotripsy applied to one renal pole damages the pole and transiently reduces renal blood flow in both kidneys. It has been shown that denervation of the kidney blunts the response to changes in renal blood flow, suggesting that renal nerves mediate, in part, the vasoconstrictor response of the un-shocked contralateral kidney to shockwave lithotripsy, and the vasoconstriction occurring in the shocked kidney.

Willis LR, Shalhav AL, Lifshitz DL, Connors BA, Blomgren PM, Simon JR, Lingeman JE. Renal Nerves Mediate Renal Vasoconstriction Caused by Shockwave Lithotripsy. Journal of Urology 165:244A, 2001.

 

Application of Low Energy Shockwaves (12 KV) to The Lower Renal Pole Prevents Hemorrhagic Injury in The Upper Pole After Application of High Energy Shockwaves (24 KV) to The Upper Pole

In this study, renal vasoconstriction following shockwave lithotripsy at low kilovoltage (12 KV) to one pole of the kidney appears to limit the bleeding and subsequent development of hemorrhagic legions caused by shockwaves applied at a higher kilovoltage (24 KV) to the other pole.

Willis LR, Evan AP, Connors BA, Blomgren PM, Shao Y, Lingeman JE. Application of Low Energy Shockwaves (12 KV) to The Lower Renal Pole Prevents Hemorrhagic Injury in The Upper Pole After Application of High Energy Shockwaves (24 KV) to The Upper Pole. Journal of Urology 165:245A, 2001.

 

Intestinal Oxalobacter Formigenes Colonization Urinary Oxalate Levels in Calcium Oxalate Stone Formers

It is known that oxalobacter formigenes is a colonic bacterium capable of breaking intestinal oxalate. This study showed that there is a correlation between calcium oxalate stone formers and the absence of oxalobacter formigene colonization. Patients who form calcium oxalate stones, who lack oxalobacter have a higher average urinary oxalate level than patients who are oxalobacter positive. The authors suggest that patients taking quinolones will reduce the level of oxalobacter formigenes, while patients taking penicillin or Bactrim do not have any effect on the oxalobacter formigene level. They recommend giving penicillin or Bactrim to the patients who are calcium oxalate stone formers.

Troxel SA, Low RK. Intestinal Oxalobacter Formigenes Colonization Urinary Oxalate Levels in Calcium Oxalate Stone Formers. Journal of Urology 165:245A, 2001.

 

Can the Recurrence of Oxalate Stone be prevented? Role of Oxalobacter Formigenes in Stone Recurrence.

90% or urinary calculi are calcium oxalate stones. Oxalobacter formigenes is a oxalate degrading bacterium, colonizing the GI tract in humans. This study demonstrated a relationship between urinary oxalate levels and the intestinal bacterium, oxalobacter formigenes. The absence of the bacterium in the intestines appears to result in a higher risk of recurrent oxalate stone disease by causing hyperoxaluria.

Tunuguntla HSGR. Can the Recurrence of Oxalate Stone be prevented? Role of Oxalobacter Formigenes in Stone Recurrence. Journal of Urology 165:246A, 2001.

 

ERBIUM:YAG Lithotripsy

Previous studies demonstrate that urinary calculi absorb laser energy more efficiently at the wavelength of 2.9 micrometers (corresponding to Erbium:YAG), than to 2.1 micrometers (corresponding to Holmium:YAG Laser). Erbium:YAG laser lithotripsy results in greater fragmentation than Holmium:YAG lithotripsy when normalized for irradiation. Erbium;YAG is transmitted efficiently in water, resulting in forward vapor expansion and minimal lateral expansion with little risk of collateral damage. Future work to improve the optical fiber of Erbium:YAG energy requires investigation.

Chang KF, Le H, Welch AJ, Kamerer AD, Teichman JM. J. Erbium:YAG Lithotripsy Journal of Urology 165:360A, 2001.

 

A New Ultrasonic and Lithoclast Combination for Highly Effective Percutaneous Nephrolitholapaxy.

The new lithotripter consists of a lithoclast Master (EMS) and a new ultrasonic device (EMS). 55 consecutive patients underwent percutaneous nephrolithotomy (PCNL) for partial or complete staghorn calculi. This new device has a new headpiece, foot switch, and pinch valve for irrigation and a control unit. This new lithotripter provides easy use and demonstrated double the efficacy of either lithotripter alone.

Hofmann R, Olbert P, Wille S, Varga Z, Heidenreich A. A New Ultrasonic and Lithoclast Combination for Highly Effective Percutaneous Nephrolitholapaxy. Journal of Urology 165:362A, 2001

 

First Clinical Experience of Laser Lithotripsy Using the Partially Frequency-Doubled Double-Pulse Neodym-Yag Laser ("FREDDY")

Partially Frequency-Doubled Double-Pulse Neodym: Yag laser or "FREDDY", was utilized with flexible ureteroscopy in the treatment of 50 patients with urolithiasis. Complete disintegration of stones was achieved in 80.1%. There was no ureteral perforation in any cases. Lithotripsy with "FREDDY" allows an easy and low-cost entry into laser lithotripsy. There was insufficient disintegration of uric acid and cystine stones, but this is outweighed by the safe laser application without danger of ureteral perforations.

Stark L, Carl P. First Clinical Experience of Laser Lithotripsy Using the Partially Frequency-Doubled Double-Pulse Neodym-Yag Laser ("FREDDY"). Journal of Urology 165:362A, 2001.

 

Ureteroscopy of Impacted Calculi

The treatment of impacted ureteral calculi by shockwave lithotripsy typically yields poor results and ureteroscopy may offer a therapeutic alternative. In this study, the management of impacted ureteral calculi by ureteroscopy was associated with a higher incidence of ureteral stenosis (6 of 35 patients). Etiological factors that may contribute to ureteral stenosis include prolonged impaction, mucosal edema, ureteral perforation during the procedure, and residual stone fragments encrusted in the mucosa.

Brito AH, Mitre AI, Duarte RJ, Arap S. Ureteroscopy of Impacted Calculi. Journal of Urology 165:362A, 2001.

 

Ureteroscopy in Pregnancy as a First Line Intervention For Ureteral Calculi

Renal colic during pregnancy represents a diagnostic and therapeutic challenge. When conservative therapy fails, ureteral stenting or other temporary measures may be chosen as a first line treatment, postponing definitive therapy until after delivery. In this study, hematuria (40%), fever (10%), and nausea (20%), were seen. Ureteroscopy was performed as a first line intervention in 6 patients, percutaneous nephrolithotomy in 1 patients, and double J stent placement in 3 patients. Ureteroscopy may be considered as a safe and effective treatment option in pregnant patients with renal colic requiring intervention.

Lingeman JE, Lifshitz DA, Wright I, Steele RE, Simmons GR. Ureteroscopy in Pregnancy as a First Line Intervention for Ureteral Calculi. Journal of Urology 165:373A, 2001.

 

Comparisons of The Efficacy of Two Shock Wave Generators: A Prospective Randomized Study

A prospective randomized study of 694 patients with urinary tract stones underwent either electrohydraulic (Dornier MFL 5000) or electromagnetic (Dornier Lithotripter S DLS) lithotripsy for the treatment of urinary calculi. In this study, the Dornier Lithotripter S demonstrated significant clinical advantages over the Dornier MFL 5000 with regard to shorter treatment time, lower retreatment rate, and a greater overall success rate. There was no statistically significant difference in complication rates in either of the two lithotriptors.

Sheir KZ, Madbouly K, El-Sobky E, Ghoneim MA. Comparisons of the Efficacy of Two Shock Wave Generators: A Prospective Randomized Study. Journal of Urology 165:373A, 2001.

 

What Effects The Lower Pole Stone Clearance After ESWL?

62 patients with lower pole renal calculi were treated with ESWL as first line treatment. Lower pole infundibulopelvic anatomy with a wide infundibulopelvic angle, broad infundibular width, and short infundibular length were favorable anatomical factors for stone clearance following shockwave lithotripsy. When patients have three favorable anatomical factors, ESWL should be considered the first line treatment. However, if patients have a stone size greater than or equal to 10mm, and two or more unfavorable anatomical factors, one should consider alternative treatment options other than ESWL.

Yiu TF, Yiu MK, Hung HH, Liu PL. What Effects the Lower Pole Stone Clearance after ESWL? Journal of Urology 165:374A, 2001.

 

Routine Ureteral Stenting is not necessary After Ureteroscopy: A Prospective Randomized Trial

60 consecutive renal units were prospectively randomized into either a stent or no stent group following ureteroscopy for treatment of calculi or transitional cell carcinoma. Routine ureteral stenting is not indicated in patients who do not require ureteral dilation during ureteroscopic procedures. Placement of ureteral stents following ureteroscopy may be avoided, reducing overall operative time (20% reduction), surgical cost ($700 savings), and patient morbidity.

Byrne RR, Kourambas J. Auge BK, Delvecchio FC, Preminger GM. Routine Ureteral Stenting is not Necessary After Ureteroscopy: A Prospective Randomized Trial. Journal of Urology 165:375A, 2001.

 

Single Session Monotherapy Treatment for Staghorn Calculi

This was a retrospective review of 100 patients who underwent percutaneous staghorn treatment by a single surgeon in a single session. There were 90 complete staghorns and 10 partial staghorn calculi. The average anesthesia time was 110 minutes; average blood loss 450cc; transfusion rate 45%; and a stone-free rate of 86%. The average length of stay was 4.6 days. The complication rate was 7% including pneumonia, ileus, DVT, hydrothorax, and excessive hemorrhage requiring embolization. The authors reveal that multiple angular tracts are an effective, time efficient and minimally morbid single session modality for percutaneous staghorn calculus treatment.

Rotariu P, Yohannes P, Alexianu M, Kapoor R, Smith AD. Single Session Monotherapy Treatment for Staghorn Calculi. Journal of Urology 165:375A, 2001

 

Ex-Vivo Ureteroscopy: An Effective Approach Addressing Incidental Nephrolithiasis in Living Kidney Donors

Historically, urolithiasis in living related donors has been a relative contraindication or has subjected the donor to additional procedures, thereby delaying transplantation. In this study, 9 kidney donors with incidental, unilateral, non-obstructive nephrolithiasis were managed with ureteroscopy with Homium:YAG laser lithotripsy in the ex-vivo kidney, immediately prior to transplantation. The authors suggest that candidates for donor nephrectomy with incidental nephrolithiasis can safely donate and effectively have the stone burden treated by ex-vivo ureteroscopic Homium:YAG laser lithotripsy at the time of transplantation. There were no complications in the donor or the recipient related to this intervention.

Rashid MG, Wolf JS, Konnak JW, Faerber GJ. Ex-Vivo Ureteroscopy: An Effective Approach Addressing Incidental Nephrolithiasis in Living Kidney Donors. Journal of Urology 165:376A, 2001

 

Shock Wave Lithotripsy for Renal Stones: Low Success Rate after Initial Treatment Failure

To date, there is no consensus regarding the number of shockwave lithotripsy (SWL) treatment given to a single stone before considering alternative treatment modalities. In this study, 3,886 patients with 4,938 renal calculi underwent 6,426 treatments using the Dornier MFL 5000 lithotripter. Success rate for shockwave lithotripsy retreatment of kidney stones dropped from 71%, 46%, 41%, after first, second, and third treatment of the renal calculi, respectively. Alternative treatment options may be appropriate for kidney stones that fail initial shockwave lithotripsy therapy.

Pace K, Dyer S, Tariq N, Honey RJ. Shock Wave Lithotripsy for Renal Stones: Low Success Rate after Initial Treatment Failure. Journal of Urology 165:377A, 2001

 

Incidence of Renal Hematoma Formation after ESWL Using The New Dornier Doli-S Lithotriptor.

Subcapsular or perirenal bleeding is the most common side effect caused by ESWL. The incidence of hematoma formation following ESWL is between 0.2 and 0.4%. Predisposing factors to hematoma formation include uncontrolled hypertension, bleeding dyscrasias, infections, and usage of anticoagulants. Hematoma formation with the new Dornier Doli-S lithotriptor has not been reported in other studies. In the present study however, subcapsular hematomas were seen in 12% of patients (3 of 25). There were no identifiable predisposing risk factors contributing to these hematomas. All hematomas resolved without intervention.

Piper NY, Dalrymple N, Bishoff JT. Incidence of Renal Hematoma Formation after ESWL Using The New Dornier Doli-S Lithotriptor. Journal of Urology 165:377A, 2001

 

Unenhanced Helical Computed Tomography (CT) Versus Intravenous Urography (IVU) In Patients With Acute Flank Pain: Accuracy and Economic Impact.

In patients with acute flank pain, unenhanced helical computed tomography (CT) has been suggested as an alternative procedure to intravenous urography (IVU). In a prospective randomized study, 122 patients underwent either CT scan (n=59) or IVU (n=63). Direct cost for both examinations were the same ($246 US). Unenhanced helical CT scans can be performed immediately, unlike IVU's requiring bowel preparation and contrast media. CT scans required significantly less time to be performed than IVU (23 minutes vs 81 minutes). Indirect costs were much lower for CT scans. The average applied radiation dose was 6.5mSv for CT scan and 3.3mSv for IVU. CT scan found alternative pathologies in 9.1% and by IVU 5.1%. The specificity and sensitivity of CT scan was 94% and 94%, respectively; and 90% and 84% for IVU, respectively. Unenhanced helical CT tomography has a higher diagnostic accuracy and a better economic impact than IVU. Unenhanced helical CT is more effective, faster, less risky, and less expensive. CT scan detects more additional renal and extra-renal pathologies than IVU. The authors suggest that there is no disadvantage missing renal functional information of the IVU. Unenhanced helical CT should be considered the first line modality for diagnostic imaging in patients with acute flank pain.

Tabatabaei S, Harisinghani MG, Hahn PF, Mueller PR, McDougal WS. Unenhanced Helical Computed Tomography (CT) Versus Intravenous Urography (IVU) In Patients With Acute Flank Pain: Accuracy and Economic Impact. Journal of Urology 165:393A, 2001
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