Stephen P. Dretler

URETERAL STONES CLINICAL GUIDELINES PANEL SUMMARY REPORT ON THE MANAGEMENT OF URETERAL CALCULI

Purpose The American Urological Association convened the Ureteral Stones Clinical Guidelines Panel to analyze the literature regarding available methods for treating ureteral calculi and to make practice policy recommendations based on the treatment outcomes data.PURPOSE The American Urological Association convened the Ureteral Stones Clinical Guidelines Panel to analyze the literature regarding available methods for treating ureteral calculi and to make practice policy recommendations based on the treatment outcomes data. MATERIALS AND METHODS The panel searched the MEDLINE data base for all articles related to ureteral calculi published from 1966 to January 1996. Outcomes data were extracted from articles accepted after panel review. The data were then meta-analyzed to produce outcome estimates for alternative treatments of ureteral calculi. RESULTS The data indicate that up to 98% of stones less than 0.5 cm. in diameter, especially in the distal ureter, will pass spontaneously. Shock wave lithotripsy is recommended as first line treatment for most patients with stones 1 cm. or less in the proximal ureter. Shock wave lithotripsy and ureteroscopy are acceptable treatment choices for stones 1 cm. or less in the distal ureter. CONCLUSIONS Most ureteral stones will pass spontaneously. Those that do not can be removed by either shock wave lithotripsy or ureteroscopy. Traditional blind basket extraction, without fluoroscopic control and guide wires, is not recommended. Open surgery is appropriate as a salvage procedure or in certain unusual circumstances.

Report of the United States Cooperative Study of Extracorporeal Shock Wave Lithotripsy

Extracorporeal shock wave lithotripsy effectively fragments urinary calculi in the upper urinary tract and upper ureter. These fragments pass completely by 3 months in 77.4 per cent of the patients with single stones. Risk of obstruction, increased postoperative pain, need for additional urological operations and retained fragments are low for stones less than 1 cm. in size. As the number of stones treated or single stone size increases above 1 cm. the risk for these factors increases. Adjunctive urological surgical management is required in 9 per cent of the patients preoperatively and 8 per cent postoperatively. Only 0.6 per cent of the patients require some type of open operation to resolve the stone problems after extracorporeal shock wave lithotripsy. Hemorrhage, obstruction by fragments, severe pain and urinary infection all constitute known complications and require careful urological management of all patients. Hospitalization averages 2 days after treatment and patients usually return to work within a few days after they are discharged from the hospital.

Nephrolithiasis Clinical Guidelines Panel Summary Report on the Management of Staghorn Calculi

The American Urological Association Nephrolithiasis Clinical Guidelines Panel recommendations for managing struvite staghorn calculi are based on a comprehensive review of the treatment literature and meta-analysis of outcome data from the 110 pertinent articles containing viable, unduplicated data. The panel concluded that the 3 most significant outcome probabilities are those of being stone-free, undergoing secondary unplanned procedures and having associated complications. Panel guideline recommendations for most standard patients are that neither shock wave lithotripsy monotherapy nor open surgery should be a first-line treatment choice but that a combination of percutaneous stone removal and shock wave lithotripsy should be used.

The Pulsed Dye Laser for Fragmenting Urinary Calculi

The properties of a laser which effect stone fragmentation have been studied. The pulsed dye laser emitting at 504 nm. in one microsecond duration pulses appears to be the optimum out of a wide range of parameters tested. The laser is coupled to a 200 micron core fiber; this complete with its cladding has a total diameter of only 0.25 mm. Most calculi are fragmented by a series of pulses of up to 30 mJ. The system is used by firing bursts of pulses with the fiber actually in contact with the stone. The result is a very controlled fragmentation which is particularly suited to use in the confines of the ureter. This modality of treatment utilises less energy than ultrasound or electrohydraulic probes to fragment a stone and the very fine, flexible fiber represents a considerable miniaturization.

Oxalobacter formigenes May Reduce the Risk of Calcium Oxalate Kidney Stones

Most kidney stones are composed primarily of calcium oxalate. Oxalobacter formigenes is a Gram-negative, anaerobic bacterium that metabolizes oxalate in the intestinal tract and is present in a large proportion of the normal adult population. It was hypothesized that the absence of O. formigenes could lead to increased colonic absorption of oxalate, and the subsequent increase in urinary oxalate could favor the development of stones. To test this hypothesis, a case-control study involving 247 adult patients with recurrent calcium oxalate stones and 259 age-, gender-, and region-matched control subjects was performed. The prevalence of O. formigenes, determined by stool culture, was 17% among case patients and 38% among control subjects; on the basis of multivariate analysis controlling demographic factors, dietary oxalate, and antibiotic use, the odds ratio for colonization was 0.3 (95% confidence interval 0.2 to 0.5). The inverse association was consistently present within strata of age, gender, race/ethnicity, region, and antibiotic use. Among the subset of participants who completed a 24-h urine collection, the risk for kidney stones was directly proportional to urinary oxalate, but when urinary factors were included in the multivariable model, the odds ratio for O. formigenes remained 0.3 (95% confidence interval 0.1 to 0.7). Surprisingly, median urinary oxalate excretion did not differ with the presence or absence of O. formigenes colonization. In conclusion, these results suggest that colonization with O. formigenes is associated with a 70% reduction in the risk for being a recurrent calcium oxalate stone former.

An evaluation of ureteral laser lithotripsy: 225 consecutive patients

We treated 225 patients with 227 ureteral calculi (5 steinstrasse) via the pulsed dye laser with 9.5F rigid, 7.2F semirigid and flexible, steerable ureteroscopes. The 222 calculi (excluding steinstrasse) were fragmented by laser alone in 141 cases (64%), laser and a basket in 30 (13%), and laser and extracorporeal shock wave lithotripsy in 33 (15%). The laser failed in 18 cases (8%). Of the 222 calculi 165 were impacted. Of 29 impacted upper ureteral calculi 15 were treated by laser disimpaction and fragmentation, 13 by laser disimpaction followed by extracorporeal shock wave lithotripsy and 1 by an operation. Of 42 mid ureteral calculi (30 impacted) 24 were treated successfully by laser fragmentation and 14 by fragmentation followed by extracorporeal shock wave lithotripsy, while 4 failed laser therapy. Among 151 lower ureteral and tunnel calculi laser fragmentation was successful in 132 cases (87%), laser followed by extracorporeal shock wave lithotripsy was successful in 6 and 13 failed laser treatment. There were no ureteral strictures and no ureteral injuries related to use of the laser. The pulsed dye laser is safe and effective treatment for impacted upper and mid ureteral calculi, small mid ureteral calculi in female patients, and lower ureteral calculi in male and female patients. Use of the laser in conjunction with other endourological methods resulted in the need for an operation in 2 of 225 patients (0.9%) with ureteral calculi.

Management of the impacted ureteral calculus.

The management of 42 impacted ureteral calculi is reviewed. Impacted stones were defined by the inability to pass a guide wire or catheter on initial attempts. Stones were impacted in the upper ureter in 10 patients, mid ureter in 11 and lower ureter in 21. Upper ureteral stones were treated in 8 patients by extracorporeal shock wave lithotripsy after disimpaction by laser or other techniques. Mid ureteral stones were treated by laser alone in 7 patients and by extracorporeal shock wave lithotripsy after disimpaction in 4. Lower stones were treated by laser in 17 patients and ultrasound in 2. Complications included 3 major and 5 minor perforations, and 4 false passages. Treatment was successful without an open operation in 40 of 42 patients (95%). Our current approach to impacted ureteral calculi involves passing a rigid ureteroscope to the stone, with disimpaction performed by laser fragmentation or other dislodgement maneuvers. Proximal stones or large fragments then are treated by extracorporeal shock wave lithotripsy. Mid ureteral stones are treated similarly, unless they are so fragile that in situ fragmentation may be completed easily. Lower ureteral stones are fragmented in situ, with hard fragments extracted by basket. Alternative treatments for impacted calculi at all levels include unstented in situ extracorporeal shock wave lithotripsy, antegrade ureteroscopy and, finally, an operation.

Cystine Calculi—Rough and Smooth: A New Clinical Distinction

Four stones each from 2 populations of cystine calculi, 1 with a rough external surface (cystine-R) and the other smooth (cystine-S), were studied for their crystal structure with stereoscopic and scanning electron microscopy. Two stones each of cystine-R and cystine-S, calcium oxalate monohydrate, calcium oxalate dihydrate, struvite plus apatite and brushite were fragmented with extracorporeal shock wave lithotripsy and the fragmentability was compared. Fragments resulting from cystine-R and cystine-S extracorporeal shock wave lithotripsy were examined under the stereoscope to assess the plane of cleavage or fracture. Results show that cystine-R stones are comprised of well formed blocks of hexagonal crystals, whereas cystine-S calculi have small, irregular and poorly formed interlacing crystals. The center of cystine-R stones was similar to that of the periphery but the center of cystine-S stones was formed of blocks of hexagons similar to but smaller than the cystine-R calculi. Fragmentation with extracorporeal shock wave lithotripsy revealed that cystine-S stones are the least fragile, calcium oxalate dihydrate and struvite plus apatite were the most fragile, and cystine-R, brushite and calcium oxalate monohydrate calculi were in the intermediate fragility range. The possibility of the patient having a cystine-R calculus should be considered during therapeutic procedures.

Extracorporeal Shock Wave Lithotripsy of Caliceal Diverticula Calculi

We reviewed 10 patients with calculi in caliceal diverticula to determine whether they could be treated successfully by extracorporeal shock wave lithotripsy. Of the patients 7 required 1 and 3 required 2 treatment attempts to fragment the calculi completely. After a minimum followup of 3 months (mean 5.9 months) 2 patients (20 per cent) had passed successfully all of the stone fragments, while 3 (30 per cent) had passed more than half and 5 (50 per cent) had passed less than half of the fragments. Of the 8 patients with residual fragments only 3 had persistent symptoms indicating that symptom relief is not dependent on complete stone removal. The possibility of producing a satisfactory result (70 per cent free of symptoms) and the low morbidity of extracorporeal shock wave lithotripsy suggest that this treatment may be appropriate for calculi in caliceal diverticula.

An algorithm for the management of ureteral calculi.

We evaluated 158 patients with ureteral calculi (28 impacted in the ureteropelvic junction, 42 in the upper, 29 middle and 36 lower third of the ureter, and 23 in the intramural tunnel) treated by extracorporeal shock wave lithotripsy, percutaneous ultrasonic lithotripsy, ureteroscopic methods, chemolysis or surgery. Of the patients 92.5 per cent were treated successfully by endourological methods. Twelve patients (7.5 per cent) required an operation. Extracorporeal shock wave lithotripsy was successful in 61 per cent of the patients without placement of a ureteral stent and in 100 per cent in whom stent placement or stone dislodgement was successful. Ureteroscopic removal was successful in 52 of 56 patients with lower third and intravesical tunnel ureteral calculi. An algorithm for ureteral calculi management is developed, which emphasizes stent bypass and extracorporeal shock wave lithotripsy for upper third or ureteropelvic junction calculi, ureteroscopic removal or stent bypass with extracorporeal shock wave lithotripsy for middle third calculi, and ureteroscopic techniques for lower third and intramural tunnel calculi. Percutaneous ultrasonic lithotripsy, chemolysis and surgery are recommended as complementary methods.