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Second generation lithotriptors offer the advantage of anesthesia-free fragmentation of renal and ureteral calculi but they frequently require multiple treatments to attain a stone-free status. However, excessive single lithotripsy sessions or multiple treatments may be associated with significant damage to the kidney. For some clinicians a common treatment philosophy involves evaluation of serial plain abdominal films every 24 hours after lithotripsy and immediate retreatment of all patients with incomplete fragmentation. To avoid unnecessary retreatments and, thus, minimize potential renal damage, we prospectively evaluated 100 patients undergoing lithotripsy on a Wolf Piezolith 2300 device. Patients were routinely treated with 4,000 shocks at 1,100 bar. Serial plain abdominal films were obtained at 1 day and 2 weeks after lithotripsy. The need for retreatment was determined by the plain abdominal film results. Additional therapy was considered necessary if there was no stone fragmentation or if residual fragments measured greater than 4 mm. Of the patients whose plain abdominal film at 24 hours indicated the need for a repeat treatment 43% were stone-free on the 2-week film. Thus, these patients were spared an unnecessary treatment by allowing adequate time for the stone fragments to pass spontaneously. Our data suggest that repeat treatments on second generation lithotriptors should not be performed within 24 hours. Rather, the patient should be reevaluated at least 1 to 2 weeks later to avoid unnecessary retreatment with the attendant potential for renal injury. In addition, when comparing the retreatment rates of various lithotriptors, one should also consider the treatment philosophy used at the particular institution and the timing of the radiographic studies used to determine the stone-free status.

Ketoconazole was used to probe the pathogenetic importance of the serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentration in 19 patients with well characterized absorptive hypercalciuria (AH). Patients were studied while receiving a constant metabolic diet before and after 2 weeks of ketoconazole administration (600 mg daily). Twelve of the patients were classified as ketoconazole responders, because in conjunction with a reduction of serum 1,25-(OH)2D from 113 +/- 36 to 70 +/- 26 pmol/L, intestinal 47Ca absorption decreased from 76.3 +/- 8.1% to 61.9 +/- 7.7%, and 24-h urinary Ca excretion declined from 7.6 +/- 1.4 to 5.7 +/- 1.1 mmol (P < 0.001 each). In these patients, intestinal 47Ca absorption was directly correlated with serum 1,25-(OH)2D levels and 24-h Ca excretion. In another group of 7 patients, termed ketoconazole nonresponders, despite reduction of 1,25-(OH)2D from 122 +/- 36 to 84 +/- 17 pmol/L (P = 0.015), there was no significant change in intestinal Ca absorption (76.0 +/- 8.2% to 72.1 +/- 10.6%) or 24-h urinary Ca excretion (7.3 +/- 1.3 to 7.2 +/- 1.0 mmol). In these patients, neither intestinal Ca absorption nor urinary Ca excretion was correlated with serum 1,25-(OH)2D levels. It, thus, appears that AH is a heterogeneous disorder comprised of both vitamin D-dependent and vitamin D-independent subsets. Although useful to probe the pathogenesis of AH, chronic treatment with ketoconazole is not recommended because of its generalized effects in inhibiting steroid synthesis.

Microhardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (10%)/calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calcium apatite (10%); calcium oxalate monohydrate (85%)/calcium apatite (15%); and cystine (100%) were measured. Using Knoop and Vickers indenters the effects of chemical composition and microstructure on the microhardness measurement were assessed. Calcium oxalate monohydrate, magnesium ammonium phosphate hydrogen, and cystine stones, without apparent structure pattern, showed neither regional nor directional differences in their microhardness. In contrast, calcium apatite stones, with distinctly concentric laminae structure, showed regional variations which were correlated with the chemical composition of stone constituents. Scanning electron microscopy of the indenter impressions were taken to help in interpreting the directional dependence in Knoop hardness measurements with respect to the microstructure of the calculi. Vickers measurements showed the crystalline stones were isotropic within a layer. Combined results of Knoop and Vickers measurements indicate that the anisotropic Knoop hardness readings seen in the laminated regions were structural but not material-based. Implications of the results for the fragmentation of renal calculi in extracorporeal shock wave lithotripsy are discussed.

A standard stone phantom was used to compare stone damage after extracorporeal shock wave administration from electrohydraulic, electromagnetic and piezoelectric lithotripters. For each machine, a low and high shock wave intensity setting was chosen: 18 & 24 kV for electrohydraulic; 16 & 19 kV for electromagnetic; power levels 1 and 4 for piezoelectric. The shock wave was focused either at the front (surface facing the wave source) or back surface of the stone and 50, 100, 200 or 400 shocks were delivered to different stone groups. Effects of varying physical properties in the stone phantom were also investigated. Stone damage was described in terms of volume loss and both depth and width of the resulting damage crater. At the lower intensity settings, all three machines produced stone volume loss which was linearly related to the number of shock delivered. At higher intensity settings, volume loss increased rapidly as the number of shocks increased. With the same number of shocks, stone volume loss was greatest with the electrohydraulic machine, followed by electromagnetic and piezoelectric lithotripters for both low and high intensity settings. Damage craters from the piezoelectric device were narrow and deep; those from the electromagnetic machine were of the shape of a right angle circular cone; whereas those from the electrohydraulic lithotripter were shallow and wide. At the high intensity settings, damage from the piezoelectric and electrohydraulic lithotripters appeared to depend upon the position of the focal point with a higher volume loss when the shock waves were targeted at the front surface of the stone. For the electromagnetic device, a higher volume loss was found when we positioned the focal point at the back surface of the stone phantom. Stone phantoms with lower mechanical strength and acoustic impedance were more easily damaged than those with higher values. Finally, a computer regression model was developed to express volume loss in terms of the intensity setting, focal position and number of shocks for each lithotripter.

Selective medical therapy of nephrolithiasis is highly effective in preventing new stone formation. A remission rate of greater than 80% and an overall reduction in individual stone formation rate of greater than 90% can be obtained in patients with nephrolithiasis. In patients with mild to moderate severity of stone disease, virtually total control of stone disease can be achieved with a remission rate of greater than 95%. The need for stone removal may be dramatically reduced by an effective prophylactic program (Fig 6). Selective pharmacological therapy of nephrolithiasis also encompasses the advantages of overcoming nonrenal complications as well as averting certain side effects that may be caused by nonselective medical therapy. Despite these advantages, it is clear that selective medical therapy cannot provide total control of stone disease. A satisfactory response requires continued, dedicated compliance by patients to the recommended program and a commitment by the physician to provide long-term follow-up and care.

To evaluate for the possible differences in the extent of pathologic injury occurring following treatment with various lithotripsy modalities, we subjected rabbits to treatment on either an electrohydraulic, electromechanical, or piezoelectric lithotripter. Functional evaluations by enzymuria failed to reveal any difference in the extent of damage between the lithotripters. Pathologic evaluation of the kidneys revealed that both electrohydraulic and electromechanical lithotripsy resulted in an increased instance of acute subcapsular hematoma and fibrosis when compared to piezoelectric treated kidneys (p less than 0.001). Despite the definitive differences noted in the acute animals, there was no significant variation in the area of permanent renal damage that occurred between the various lithotripters.

Previous studies have demonstrated that renal parenchymal injury following extracorporeal shock wave lithotripsy is dependent upon shock wave power as well as the total number of shock waves administered. In order to determine the deleterious effects of temporal versus cumulative doses of shock wave administration, adult female rabbits were divided into five groups receiving either: 1000 shock waves in one session; 2000 shock waves in one session; 2000 shock waves in two sessions, one week apart; unilateral nephrectomy without lithotripsy; or anesthesia only as control population. One month following lithotripsy, renal functional studies for gamma glutamyl transferase and N-acetyl-beta-glucosaminidase revealed persistent enzymuria in the animals treated with 2000 shocks in one session. Pathologic studies in these animals confirmed an increased area of periglomerular and intratubular fibrosis when compared to animals managed by either 1000 shocks or 2000 shocks in divided doses (p less than 0.01). These findings suggest the importance of avoiding single treatments with large doses of shock waves and favor the administration of multiple small-doses of shock waves to minimize renal damage during the treatment of patients with hard or large calculi.

Extracorporeal shock wave lithotripsy has significantly altered the management of symptomatic renal and ureteral calculi. Yet in an effort to limit the potentially harmful effects of shock waves, while still maintaining or maximizing stone fragmentation, one must understand basic shock wave physics. This report presents a brief overview of the physical properties of shock waves and describes three different areas of shock wave physics investigation: measurement of shock wave pressures, assessment of stone fragmentation, and development of a stone phantom to allow the comparison of various lithotripsy devices. It is only through additional study of the basic physics of high-energy shock waves that we will be able to further enhance the clinical benefits of extracorporeal shock wave lithotripsy. Further understanding of the individual characteristics of a shock wave pressure field such as peak positive pressure, peak negative pressure, pulse duration, and size/shape of the focal region will allow the subsequent enhancement of stone fragmentation while minimizing the potential for shock wave injury to surrounding tissues.

The differential diagnosis of the acutely enlarged testis includes numerous benign and malignant disease processes. Most are treated with radical orchiectomy due to difficulty in differentiating between these disorders preoperatively. Saving the involved testis, prevention of recurrent infectious disease in the opposite testis and prevention of systemic manifestations of testicular disease are but a few of the reasons for accurate diagnosis of the acute scrotum. We report a rare case of brucellosis presenting as an acute scrotal mass and stress the importance of accurately identifying the specific etiology of testicular pathology to prevent long-term morbidity.

Extracorporeal shock wave lithotripsy has revolutionized the treatment of urinary calculi. It should be considered the treatment of choice for renal stones smaller than 2 cm and for the majority of ureteral calculi, under which circumstances success rates approaching 80 to 90 per cent may be anticipated. Larger renal calculi or impacted ureteral stones probably should be managed by endoscopic techniques with or without adjunctive intracorporeal (ultrasonic or electrohydraulic) lithotripsy or laser fragmentation. Recent modifications in lithotripter design have been focused on the development of pain-free lithotripsy. Concomitant with a decrease in power, however, is an attendant decrease in the efficiency with which stones can be fragmented, resulting in an increase in the number of lithotripsy treatments required for adequate stone fragmentation. Additionally, sonography is assuming an increasing role in stone localization, and its use will require sonographic training on the part of the urologist. Biliary lithotripsy has been promising in preliminary European studies, with success rates approaching 90 per cent. It must be noted, however, that the U.S. experience has not been as impressive. Moreover, only 20 to 30 per cent of patients referred for biliary lithotripsy appear to be optimal candidates for this new technique. Adjunctive dissolution of gallstones with chronic oral medical therapy may be required after biliary lithotripsy, and long-term follow-up studies still need to be performed. Finally, the potential deleterious effects of extracorporeal shock wave lithotripsy must always be kept in mind. Although the majority of clinical and animal investigations have documented no significant long-term alterations in renal function, care must still be exercised when performing lithotripsy with the knowledge of the potential for long-term injurious effects on the functioning renal parenchyma.

Nine women with laxative abuse and predominantly ammonium urate renal calculi underwent metabolic studies to identify common chemical abnormalities and determine pathophysiology. The 24-hour urine studies demonstrated marked decreases in volume (902 cm.3), sodium (28 mEq.), citrate (116 mg.) and potassium (21 mEq.). A significant elevation in ammonium urate supersaturation was found compared to control subjects when studied by the computer model EQUIL 2. Of the patients 7 had 1 or more urine specimens positive for phenolphthalein. Gastrointestinal loss of fluid and electrolytes allowed for chronic extracellular volume depletion. Intracellular acidosis was present as judged by low urinary citrate and potassium. The fact that the ion product for ammonium urate is increased significantly compared to controls reflects the stated pathophysiological changes. Laxative abuse should be suspected whenever a woman has an ammonium urate renal calculus in sterile urine.

Negative calcium balance and calcium nephrolithiasis are two sequelae of chronic metabolic acidosis. To establish the effects of acidosis on calcium and vitamin D metabolism, we have examined a group of nine patients with incomplete distal renal tubular acidosis. Patients were studied during a control phase and after eight months of potassium citrate treatment, 60 to 80 meq daily. Potassium citrate caused a significant decrease in urinary calcium. The fractional intestinal calcium absorption increased significantly, yet no change was observed in serum vitamin D levels. The estimated calcium balance increased significantly from -70.2 +/- 63.8 to +66.7 +/- 48.7 mg/d (P less than 0.01). Thus, potassium citrate treatment improved the estimated calcium balance by lowering urinary calcium while increasing the fractional intestinal calcium absorption. The original hypercalciuric state, its correction to normocalciuria, and the augmentation of intestinal calcium absorption seen in these patients are probably independent of vitamin D control since there was no change noted in serum 1,25-dihydroxyvitamin D levels.

Acute urinary retention in female patients often is attributed to psychogenic disturbances. However, it is apparent that this problem may be the harbinger of significant organic illness. Our experience with 27 patients reveals that careful evaluation and appropriate treatment prevent further urological complications and aid in the diagnosis of underlying pathological conditions.

Surgical management of urinary calculous disease has changed dramatically in the past decade. The development of percutaneous nephrostomy techniques has allowed new access to upper tract stones. Percutaneous removal of large calculi was made possible by the development of ultrasonic and electrohydraulic lithotripsy. All upper tract calculi can now be removed in 70 to 100 per cent of cases with minimal complications. Nephrostolithotomy has reduced transfusion rates and hospitalization costs and has markedly shortened convalescence periods compared with open surgery. Ureteroscopy followed nephrostolithotomy as advanced fiberoptic technology allowed the development of the small-caliber instruments required for this procedure. With experience, successful stone retrieval has occurred in 90 per cent or more of cases, again with minimal complications. As nephrostolithotomy and ureteroscopy have become available, the subspecialty of endourology has emerged and significantly changed the management of urinary tract calculi. Perhaps the most significant advance in stone therapy has been the design and implementation of extracorporeal shock wave lithotripsy. With this noninvasive technique, most renal and proximal ureteral calculi can be effectively treated with minimal morbidity and convalescence. Research in lithotripter design is continuing, with more advanced and effective machines on the horizon. The applicability of extracorporeal therapy for the treatment of biliary tract calculi is currently under investigation. Finally, one should not disparage medical therapy for recurrent nephrolithiasis. A comprehensive metabolic evaluation combined with selective medical therapy provides almost complete relief from recurrent stone formation and makes medical therapy an integral component of treating the patient with renal or ureteral calculi.

Previous experimental investigations of embryonic kidney development with in vitro organ-culture techniques have been limited by the short duration of graft viability and lack of detailed anatomic development. In a modified application of the chick chorioallantoic-membrane (CAM) grafting technique, we have transplanted 11-day-old undifferentiated embryonic murine kidney rudiments and studied their differentiation and early morphogenesis. Surviving grafts, maintained for 5-10 days on the CAM, demonstrated well-developed convoluted secretory tubules and highly branched collecting ducts. Definitive glomeruli were also identified in these grafts by the presence of efferent tubules, visceral and parietal epithelium, capillary tuft, and Bowman's space. In vitro branching of the ureteric bud preceded formation of definitive tubules. Sections of the CAM grafts appeared histologically comparable to the 14-15-day in vivo embryonic metanephros. Grafts of 10-day-old rudiments showed minimal kidney development; fewer grafts survived, fewer tubules were formed, and fewer glomeruli developed. Our results indicate that the CAM is an efficient site for in vitro murine kidney development with both vascularization of the explant and extensive maturation, including the appearance of primitive nephron units.

Previous experimental investigations of embryonic kidney development with in vitro organ culture techniques have been limited by the short duration of explant viability. Utilization of chick chorioallantoic membranes for transplanting undifferentiated murine kidney rudiments has allowed vascularization of the grafts with advanced maturation and the appearance of early nephron units.

Uric acid stone disease is dependent on three pathogenetic factors: acid urine pH, low urine volume, and hyperuricosuria. The management of nonobstructing uric acid calculi should include maintenance of an alkaline urine, an increase in urine volume, and reduction in urinary uric acid excretion. It appears that potassium alkali may avoid the complication of calcium stone formation in patients with uric acid stones. In patients with obstructing uric acid calculi, more rapid dissolution may be accomplished with intravenous alkalinization or direct irrigation of the stone with an alkaline solution.

Alkali therapy is used commonly to prevent recurrent stone formation in patients with distal renal tubular acidosis. We compared the effects of potassium citrate to those of sodium citrate in 6 well defined cases of incomplete distal renal tubular acidosis. The patients were studied during a control phase, during potassium citrate treatment (80 mEq. per day) and during sodium citrate treatment (80 mEq. per day) chosen in random order. Potassium citrate caused a decrease in urinary calcium and a significant increase in urinary citrate that resulted in a significant decrease in the urinary saturation of calcium oxalate. It did not alter the saturation of brushite and sodium urate. However, while sodium citrate also was able to increase the urinary citrate level, there was no decrease in the urinary calcium (owing to the increased sodium load). Thus, the urinary saturation of calcium oxalate did not decrease as much as with potassium citrate and the saturation of brushite increased significantly. Moreover, the urinary saturation of sodium urate increased significantly owing to the enhanced sodium excretion. The results suggest that potassium citrate therapy may retard the crystallization of calcium oxalate and may not cause calcium phosphate crystallization. In contrast, sodium citrate may have no effect or it sometimes may accentuate the crystallization of calcium salts. Thus, our study supports the potential clinical advantage of potassium citrate therapy over sodium alkali treatment in patients with incomplete distal renal tubular acidosis and recurrent calcium nephrolithiasis.

Anti-factor VIII antibodies, inherited or acquired inhibitors of the factor VIII molecule, have not been reported previously in the urological literature. Although more common in hemophiliac patients who have received multiple transfusions, this anticoagulant may be the cause of severe hemorrhage in nonhemophiliac patients. We describe a patient with carcinoma of the prostate and an unsuspected anti-factor VIII antibody, who experienced excessive postoperative bleeding and prolonged hospitalization following a vesicolithotomy and bilateral orchiectomy. A prolonged partial thromboplastin time and a significant decrease in measurable factor VIII clotting activity in a patient with no history of bleeding problems are essential clues in making the diagnosis of a factor VIII inhibitor. This coagulation defect is treated best with prothrombin complex concentrates, which contain vitamin K dependent clotting factors.

The effect of long-term hydrochlorothiazide therapy on renal calcium excretion was measured in 12 well defined cases of absorptive hypercalciuria and 10 of renal hypercalciuria. Patients were studied during a control phase, at 3 to 6 months of therapy and after long-term treatment with hydrochlorothiazide (mean 61 months for absorptive hypercalciuria and 71 months for renal hypercalciuria). Evaluation comprised measurement of urinary calcium and fractional (intestinal) calcium absorption while patients were maintained on a constant metabolic diet (400 mg. calcium per day) for 3 days. In patients with absorptive hypercalciuria urinary calcium decreased significantly at 3 months of treatment (from 266 to 137 mg. per day, p less than 0.001). However, with continued treatment urinary calcium rebounded to 197 mg. per day. Of the patients with absorptive hypercalciuria 50 per cent were hypercalciuric (greater than 200 mg. per day) on long-term treatment, whereas none was hypercalciuric at 3 months. In contrast, urinary calcium in the patients with renal hypercalciuria decreased from 299 to 104 mg. per day (p less than 0.001) at 3 months of treatment and remained reduced (116 mg. per day) during long-term treatment. Intestinal calcium absorption was increased initially and remained unchanged throughout treatment in the patients with absorptive hypercalciuria. In patients with renal hypercalciuria intestinal calcium absorption decreased significantly after short-term treatment with hydrochlorothiazide and remained so after long-term therapy. The results suggest that, unlike patients with renal hypercalciuria, some with absorptive hypercalciuria lose the hypocalciuric effect of hydrochlorothiazide during long-term treatment.

Technical advances and operator experience have resulted in a rapid and marked streamlining of the percutaneous approach to renal calculi. The development of nephrostomy tract balloon dilators, improved grasping instruments and the use of assisted local anesthesia have been integral in reducing the morbidity and cost of the procedure. We report our initial favorable experience in the use of percutaneous stone removal on an outpatient basis. All 5 patients underwent an uncomplicated 1-stage stone removal. Cost for outpatient percutaneous stone removal was substantially less than for surgery or extracorporeal shock wave lithotripsy.

To document more clearly the effect of selective medical treatment on the course of nephrolithiasis, we surveyed 103 consecutive patients being followed in our stone clinic. Of the patients who initially had existing stones within the kidneys 69 per cent experienced no symptoms while undergoing medical therapy, compared to 96 per cent of those who had no existing stones. In all subjects studied new stone formation was reduced in more than 95 per cent and no new stones were formed in more than 75 per cent. An operation for newly formed calculi was necessary in only 2 per cent of the patients on medical therapy, whereas 58 to 69 per cent of the patients required an operation for new stones before beginning medical treatment. We believe that selective medical treatment has an important role in the over-all management of nephrolithiasis. Appropriate medical therapy may decrease significantly the number of new stones formed and may obviate the need for a repeat stone operation. Therefore, medical treatment should be an important adjunct to percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy.

To evaluate the impact of the percutaneous removal of renal calculi we compared 41 patients who had undergone open renal surgery to 88 patients who had a one- or two-stage percutaneous nephrostolithotomy for symptomatic urolithiasis. The two groups were similar with regard to stone size, stone location, treatment success, and complication rates. However, for patients with calculi 2.5 cm or smaller in diameter, the percutaneous procedure resulted in lower postoperative morbidity, more rapid convalescence, less hospital cost, and greater patient satisfaction. For patients with calculi larger than 2.5 cm in diameter, the percutaneous approach was slightly more expensive than open surgery but resulted in a markedly shortened convalescent period. In our experience, percutaneous nephrostolithotomy performed in a single stage under assisted local anesthesia was the most efficacious and least expensive of the percutaneous approaches.

Flexible fiberoptic technology was first applied to cystoscopy in 1973, with greatly increased usage since 1982. Most procedures formerly performed with rigid cystoscopes can be done using flexible cystoscopes with minimal or no anesthesia. Patient positioning and precystocopy preparation and draping are simplified with the flexible fiberoptic instruments. Complete examination of the urethra and bladder can be performed with a single-lens system and with the patient in a variety of positions. Fiberoptic cystoscopy is limited in patients who are bleeding or have blood clots in their bladders. Withdrawal of irrigant or bladder drainage is cumbersome, and the fiberoptic image is currently not of the same caliber as that of the rigid-lens systems. Fiberoptic cystoscopy has become the procedure of choice for many urologists for ureteral stenting prior to extracorporeal shock-wave lithotripsy. With the advent of lithotripters that require no anesthesia, this application is likely to broaden. Future applications of flexible cystoscopy may include a flexible videocystoscope for use in diagnostic and therapeutic procedures.

Urinary glycosaminoglycans are thought to be macromolecular inhibitors of calcium stone formation. The 24-hour excretion of urinary glycosaminoglycans was measured quantitatively in 24 normal subjects and 206 patients with different etiologies of stone disease. In both groups a positive correlation was found between urinary glycosaminoglycans and total urinary volume and urinary sulfate. In normal subjects total urinary volume was r equals 0.716, p less than 0.001 and urinary sulfate was r equals 0.813, p less than 0.001, while in patients with stones these values were r equals 0.338, p less than 0.001 and r equals 0.326, p less than 0.001, respectively. The only significant difference in excretion of urinary glycosaminoglycans between the groups was found in the subgroup of patients with type I absorptive hypercalciuria. The type I absorptive hypercalciuria value of 33.4 +/- 14.9 mg. per day in patients with stones was significantly higher than the 25.8 +/- 8.3 mg. per day detected in normal subjects (p less than 0.05). Urinary glycosaminoglycan excretion in all other subgroups of nephrolithiasis as well as in a combined group of all patients with stones showed no significant difference when compared to that of normal subjects. Thus, no major quantitative relationship could be demonstrated between urinary glycosaminoglycan excretion and calcium stone formation in this study.

The long-term effects of potassium citrate therapy (usually 20 mEq. 3 times daily during 1 to 4.33 years) were examined in 89 patients with hypocitraturic calcium nephrolithiasis or uric acid lithiasis, with or without calcium nephrolithiasis. Hypocitraturia caused by renal tubular acidosis or chronic diarrheal syndrome was associated with other metabolic abnormalities, such as hypercalciuria or hyperuricosuria, or occurred alone. Potassium citrate therapy caused a sustained increase in urinary pH and potassium, and restored urinary citrate to normal levels. No substantial or significant changes occurred in urinary uric acid, oxalate, sodium or phosphorus levels, or total volume. Owing to these physiological changes, uric acid solubility increased, urinary saturation of calcium oxalate decreased and the propensity for spontaneous nucleation of calcium oxalate was reduced to normal. Therefore, the physicochemical environment of urine following treatment became less conducive to the crystallization of calcium oxalate or uric acid, since it stimulated that of normal subjects without stones. Commensurate with the aforementioned physiological and physicochemical changes the treatment produced clinical improvement, since individual stone formation decreased in 97.8 per cent of the patients, remission was obtained in 79.8 per cent and the need for surgical treatment of newly formed stones was eliminated. In patients with relapse after other treatment, such as thiazide, the addition of potassium citrate induced clinical improvement. Thus, our study provides physiological, physicochemical and clinical validation for the use of potassium citrate in the treatment of hypocitraturic calcium nephrolithiasis and uric acid lithiasis with or without calcium nephrolithiasis.

Selective pharmacologic therapy of calcium nephrolithiasis is highly effective in preventing new stone formation. A remission rate of greater than 80 per cent and overall reduction in individual stone formation rate of greater than 90 per cent can be obtained in patients with calcium nephrolithiasis. In patients with mild-to-moderate severity of stone disease, virtually total control of stone disease can be achieved as evidenced by remission rates of greater than 95 per cent. The need for stone removal may be dramatically reduced by an effective prophylactic program. Selective pharmacologic therapy of calcium nephrolithiasis also encompasses the advantages of overcoming the nonrenal manifestations of conditions that cause stone formation as well as averting certain side effects that may be caused by nonselective medical therapy. Despite these advantages, selective medical therapy clearly cannot provide total control of stone disease. A satisfactory response requires continued, dedicated compliance by patients to the recommended program and a commitment of the physician to provide long-term follow-up and care.

It generally is believed that conservative measures of high fluid intake and dietary modification in the setting of a stone clinic could favorably influence the course of renal stone disease. To establish the effect of specific medical treatment from the stone clinic effect, we compared the results of potassium citrate therapy to those of 11 reported conservative or placebo trials. The 54 patients receiving potassium citrate chosen for this comparison had mild to moderately severe stone disease (less than 1 stone per patient per year), similar to that encountered in conservative placebo trials (mean 0.54 stones per patient per year). New stone formation was virtually eliminated by potassium citrate therapy (a decrease from 0.52 to 0.02 stones per patient per year, a remission rate of 96 per cent, p less than 0.001), whereas it continued in 39 per cent of the patients during conservative or placebo trials. However, in patients participating in conservative or placebo trials new stone formation decreased by only 54 per cent (from 0.54 to 0.25 stones per patient per year). The superior response to potassium citrate suggested that this specific medical treatment exerted an additional favorable effect on the course of stone disease above the stone clinic effect.

Distal renal tubular acidosis is a common cause of intractable calcium nephrolithiasis. We examined the effect of oral potassium citrate therapy in 9 patients with incomplete distal renal tubular acidosis diagnosed on the basis of an abnormal response to an oral ammonium chloride load. Patients were studied during a control phase and after 3 months of potassium citrate treatment (60 to 80 mEq. daily). Potassium citrate caused a significant increase in urinary pH and urinary citrate, and a decrease in urinary calcium. The urinary relative saturation ratio of calcium oxalate significantly decreased during treatment, while that of brushite did not change. Potassium citrate also was shown to inhibit new stone formation. During a mean treatment period of 34 months none of the 9 patients had new stones, although 39.3 plus or minus 79.7 (standard deviation) stones per patient formed during the 3 years preceding treatment. The results support the potential clinical advantage of potassium citrate therapy in patients with distal renal tubular acidosis and recurrent calcium nephrolithiasis.

We reviewed our experience with extracorporeal shock wave lithotripsy therapy in 138 patients who presented with mid and upper ureteral calculi. In the patients who had successful stone manipulation back into the renal collecting system the success rate was significantly higher compared to that for stones treated primarily within the ureter (92.8 versus 80.8 per cent, p less than 0.05). Among the stones treated within the ureter the success rates appeared to be similar for stones treated in situ (83.3 per cent) compared to those treated when a catheter could be placed alongside the calculus (79.3 per cent). Higher voltage and more shock waves were administered to stones treated within the ureter compared to stones that were manipulated back into the kidney. However, this increase power did not enhance the success rate. In addition, it appears that a plain film of the abdomen obtained within 24 hours of lithotripsy treatment is a good predictor of success as defined by the rate free of stones at 6 weeks of followup. Our results from a community-based multi-use lithotripsy center suggest that ureteral stone manipulation should be attempted before extracorporeal shock wave lithotripsy for mid and upper ureteral calculi.

An anatomic defect of the urethra is occasionally the cause of voiding dysfunction in the young male patient. A urethral diverticulum can often be overlooked if retrograde urethrography is not performed properly. Two cases are presented along with a discussion of the technique for dynamic retrograde urethrography. The description of a new radiologic sign indicative of a posterior bulbar urethral diverticulum, is presented.

The change in the position of the kidney during percutaneous nephrostomy is a major concern to urologists who participate in percutaneous stone removal. We report that the majority of kidneys ascend an average of 2.2 cm. when the patient turns from a supine to a prone position. This change in position is more marked on the right side and is more common in male patients. Knowledge of this anatomical variation is important to determine which patients are suitable candidates for percutaneous nephrostolithotomy and to plan a percutaneous approach to a renal or ureteral calculus.

Localized amyloidosis of the urethra is a rare pathological entity that may resemble neoplastic disease. Biopsy is required to make the appropriate diagnosis. Although localized therapy is available for obstructing, symptomatic lesions, asymptomatic lesions may be followed with conservative management and spontaneous regression has been reported. In addition, an appropriate medical evaluation should be performed to determine the presence of systemic amyloidosis.

We retrospectively reviewed the outcome of extracorporeal shock wave lithotripsy in patients with renal calculi less than 3 cm. in size who were treated at a large multi-user lithotripsy center. Patients in whom indwelling ureteral stents were placed before lithotripsy treatment were subjected to higher levels of total power (shocks times voltage), yet the rate free of stones did not differ from those treated without a stent. In addition, the patients with internal ureteral stents experienced a significantly higher incidence of urinary urgency (43 versus 25 per cent) and hematuria (40 versus 23 per cent) than nonstented patients, respectively (p less than 0.05). Also, the duration of bladder discomfort was longer for stented patients (26 versus 13 per cent) as was the duration of urinary frequency (31 versus 16 per cent), compared to nonstented patients (p less than 0.05). The results suggest that use of an indwelling ureteral stent may not contribute to a higher rate free of stones for the treatment of small to medium sized renal calculi and, in fact, it may make the treatment more uncomfortable for the patient than performing lithotripsy without ureteral stenting. Of course, in selected cases (solitary kidney, large stone burden and aid in stone localization) ureteral stenting has a useful adjunctive role in extracorporeal shock wave lithotripsy.

The advent of percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy has definitely altered the way in which symptomatic renal calculi are approached. However, these new techniques should not affect the need for appropriate diagnostic evaluation and institution of medical treatment for the prevention of recurrent nephrolithiasis. A diagnostic evaluation should identify underlying physiological and environmental defects responsible for stone formation, as well as identify specific medical disorders that cause recurrent stone formation. With this information one then can construct an appropriate treatment program that will prevent the occurrence of additional calculi. Comprehensive metabolic protocols have evolved from tedious inpatient procedures to more convenient outpatient tests that can be performed in approximately 2 weeks. In addition, the advent of automated urinalysis packages has allowed many physicians access to reliable, sophisticated technology. Further dissemination of these simplified metabolic protocols will enable more accurate diagnosis of recurrent stone disease and, hopefully, permit the institution of appropriate medical therapy by a wider group of treating physicians.

We describe a case of direct percutaneous ureterolithotomy in which the combination of antegrade control, a ureteral stent and precise fluoroscopic imaging resulted in a successful outcome. This technique may be helpful when other more traditional methods for percutaneous ureteral stone removal fail.

Clean intermittent catheterization has been an effective treatment for the management of patients with a neurogenic bladder during the last 15 years. Reported complication rates have been low and the majority of these problems have been minor. While significant problems are seen only rarely during clean intermittent catheterization, we recently diagnosed 2 potential life-threatening complications: bladder perforation and bladder necrosis. We present our experience with these major problems associated with routine clean intermittent catheterization.