The incidence of lower-pole nephrolithiasis--increasing or not?

OBJECTIVE: To determine if the incidence of lower-pole nephrolithiasis is increasing. METHODS: A previously published meta-analysis of trends in the location of stones in the kidney, using data from 1984 to 1992, determined the percentage of lower pole stones in 26,722 kidney stones treated by extracorporeal shockwave lithotripsy (ESWL). We performed prospective studies on all patients treated by ESWL for a single renal stone (not manipulated from the ureter) in two organizations: at Lithotripters Inc., 47,303 stones were treated with ESWL by 1000 urologists in private practice from 1989 to 1995. At the Midwest Urologic Stone Unit, 9357 stones were treated with ESWL by 200 urologists in private practice from 1987 to 1995. The distribution of stones in both samples was compared with that reported earlier. RESULTS: The meta-analysis for stone location trends from the previously published article suggested that the percentage of kidney stones in the lower pole at ESWL increased erratically from 1984 to 1989 but was then stable for 3 years. The Lithotripters Inc. sample showed an essentially constant incidence from 28% in 1990 to 30% in 1995, and the Midwest Urologic Stone Unit sample showed an essentially constant incidence from 35% in 1988 to 36% in 1995. CONCLUSION: The incidence of lower pole nephrolithiasis has remained stable from 1990.

Radiation awareness program for extracorporeal shockwave lithotripsy using Medstone lithotripters.

To determine the effectiveness of a radiation awareness program in reducing the radiation exposure to patients treated by a Medstone lithotripter, the exposure was calculated at the end of each extracorporeal shockwave (SWL) treatment using a table of measurements of the estimated entrance exposure rates 70 cm from the X-ray tube port. The results, related to stone size and patient weight, were distributed every month to each radiologic technologist, and a summary was sent regularly to the treating urologists. The doses before and after the introduction of the radiation awareness program were compared to determine the effectiveness of the program, and the chi-square test was used to determine statistical significance. The average calculated radiation exposure before and after introduction of the radiation awareness program was 16.39 rad and 8.26 rad, respectively, for patients with single renal stones; 17.31 rad and 9.02 rad, respectively, with single ureteral stones; 18.45 rad and 9.39 rad, respectively, with multiple renal stones; and 20.59 rad and 11.28 rad, respectively with multiple ureteral stones. These reductions in calculated radiation exposure were statistically significant only with multiple ureteral stones (P = 0.03). The only statistically significant differences in the stone-free rates, retreatment rates, and post-SWL secondary procedure rates before and after the introduction of the radiation awareness program were seen in the stone-free rates with single renal stones: 70% v 65%, respectively (P = 0.02); in the retreatment rates with single ureteral stones: 10% v 6%, respectively ( P < .01); and in the post-SWL secondary procedure rates with single renal stones: 4% v 2%, respectively (P = 0.01), and single ureteral stones: 7% v 4%, respectively (P = 0.05). The radiation awareness program resulted in a 51% reduction in the estimated radiation exposure to patients during SWL using Medstone lithotripters.

Comparison of first-generation (Dornier HM3) and second-generation (Medstone STS) lithotripters: treatment results with 145 renal and ureteral calculi in children.

The treatment results obtained in children using an unmodified Dornier HM3 or a Medstone STS lithotripter for renal and ureteral stones were compared. The Dornier HM3 was used to treat 28 renal and 10 ureteral stones, while the Medstone STS was used to treat 73 renal and 34 ureteral stones. The treatment results were compared using the chi-square test to determine statistical significance. The stone-free rate, retreatment rate, and post-SWL secondary-procedure rate were 68%, 4%, and 0, respectively, with the Dornier HM3 and 93%, 6%, and 3.6%, respectively, with the Medstone STS for single renal stones and 80%, 0, and 0, respectively, with the Dornier HM3 and 82%, 0, and 5.9%, respectively, with the Medstone STS for single ureteral stones. Abnormal anatomy (horseshoe kidney, allograft kidney) or functional interference with the passage of fragments (urinary diversion, neurogenic bladder) was present in 16% of the children treated with the Dornier HM3 compared with 5% of those treated with the Medstone STS (p = 0.36). The treatment results with the unmodified Dornier HM3 and the Medstone STS were similar except for the statistically significantly higher stone-free rate for single renal stones obtained with the Medstone STS. The difference was most likely attributable to the smaller number of children with abnormal anatomy or functional interference with the passage of fragments who were treated with the Medstone.

The use of ungating with the Medstone lithotriptor.

PURPOSE: Ungating using the Medstone* lithotriptor by 200 urologists was evaluated. MATERIALS AND METHODS: During 1994, 3,288 patients were treated by 200 urologists at 46 sites in 6 upper midwest states using 5 fixed and 3 mobile Medstone lithotriptors. Ungating was used with 58 treatments in 57 asymptomatic patients (1.8%) due to irregular cardiac rhythm in 48 caused by a bundle branch block (11), atrial fibrillation (10), slow heart rate (6) and irregular cardiac complex (21); all 48 cases were clinically insignificant, and because of urologist choice in 9 with normal cardiac rhythm (10 treatments). The cardiac simulator used for ungated lithotripsy was set at 85 shocks per minute for irregular cardiac rhythm and at 120 shocks per minute for elective use. RESULTS: The 48 treatments in patients with clinically insignificant irregular cardiac rhythm (average age 66.4 years) were performed during an average of 41 minutes of shock time. One patient had clinically significant cardiac arrhythmia that resolved with gating. The 10 elective treatments were performed during an average of 34 minutes of shock time in patients an average of 60.4 years old. The 3,231 gated treatments were performed during an average of 40 minutes of shock time in patients an average of 51 years old. CONCLUSIONS: Ungating was safe and effective in allowing patients with an irregular cardiac rhythm to be treated with the same shock time as gated cases (normal cardiac rhythm).

Extracorporeal shockwave lithotripsy or percutaneous nephrolithotomy for lower pole nephrolithiasis?

A controversy has arisen as to whether the initial form of therapy for lower pole nephrolithiasis should be extracorporeal shockwave lithotripsy (SWL) or percutaneous nephrolithotomy (PCNL). We reviewed our results with 968 single lower pole stones treated by SWL and reviewed publications comparing SWL and PCNL for lower pole nephrolithiasis. In our cases, the stone-free rate was 71.2%, the rate of repeat treatment and post-treatment secondary procedures was 6.4%, the complication rate was 0.5%, and the hospital stay was less than 24 hours in 99.3% of patients. In published series of PCNL for lower pole nephrolithiasis, the stone free rate was 70.5% to 100%, repeat treatment rates were 4% to 62.5%, the complication rates were 13% to 38%, and the hospital stay was 3.1 to 6.1 days. The rates of recurrent stone disease with PCNL were 11% to 22%, similar to the rates after SWL. The percentage of renal urolithiasis patients with lower pole calculi since we started our unit in late 1986 has remained essentially constant at 38%. Although the stone-free rate with PCNL is higher than with SWL, the lower complication rate, lower repeat treatment/secondary procedure rate, the shorter hospital stay, and the similar recurrent stone rate with SWL make SWL more clinically effective as the primary therapy for lower pole calculi less than 2 cm in diameter.

Comparison of first generation (Dornier HM3) and second generation (Medstone STS) lithotriptors: treatment results with 13,864 renal and ureteral calculi.

Some reports have shown a decreased effectiveness of extracorporeal shock wave lithotripsy (ESWL*) with newer lithotriptors. We used a first generation unmodified Dornier HM3 lithotriptor to treat 5,698 patients with renal and ureteral calculi and a second generation Medstone STS device to treat 8,166 patients with renal and ureteral calculi. The treatment results were compared using the chi-square test to determine statistical significance. The stone-free rate, retreatment rate and post-ESWL secondary procedure rate were 69.5%, 4.4% and 3.1%, respectively, with the Dornier HM3 device and 72.1%, 4.9% and 2.3%, respectively, with the Medstone lithotriptor for single renal stones, and 81.5%, 5.2% and 5.5%, respectively, with the Dornier HM3 and 83.2%, 5.2% and 5.0%, respectively, with the Medstone device for single ureteral stones. There were no statistically significant different results between a second generation tubless Medstone STS lithotriptor and the gold standard unmodified Dornier HM3 instrument.

Extracorporeal shock wave lithotripsy for renal stones with renal cysts present.

While reports differ on the effect of extracorporeal shock wave lithotripsy (ESWL*) on renal cysts, little has been written on the stone-free status following ESWL for renal calculi with renal cysts present. We studied 13 patients with renal stones plus renal cysts, and only 6 (46%) were stone-free at 3 months after ESWL. While the number of cases is small, it is believed that renal cysts may interfere with the passage of stone fragments due to the impediment of drainage, and urinary stasis from the stretching and distortion of the caliceal system by the renal cysts.

Renal function after bilateral extracorporeal shockwave lithotripsy.

We studied renal function an average of 44 months after simultaneous bilateral renal SWL in 56 patients. No cases of clinically apparent acute renal failure occurred in the early postoperative period. The glomerular filtration rate (GFR) was calculated using an empiric formula having a significant correlation with measured creatinine clearance, and a change of 20% or greater was considered a clinically significant deterioration in renal function. Of the seven patients with a preoperative serum creatinine concentration of > 1.5 mg/dL, six had an average increase of 35% in postoperative GFR attributable to relief of obstruction, while one had a 30% reduction in GFR. Among 49 patients with a preoperative serum creatinine concentration of 1.5 mg/dL or less, there was an increase in postoperative GFR in 22 patients (45%), no change in 3 (6%), and a decrease in 24 (49%), who had a higher number of multiple renal stones (p < 0.05) and of repeat SWL (p = 0.08). Nine of them (18%) had a clinically significant decrease in GFR of > 20%. A review of the literature showed a long-term reduction of function in the individual human kidney after SWL in some cases of a solitary kidney and in some cases with an untreated contralateral kidney. Because there is no evidence that an untreated contralateral kidney aids the long-term recovery of the function of a treated kidney in all cases, simultaneous or separate bilateral renal SWL would not influence this long-term reduction in renal function, which was felt to occur with multiple renal stones and repeat SWL.

Nonstent or noncatheter extracorporeal shock-wave lithotripsy for ureteral stones.

OBJECTIVE: To determine if a ureteral stent or catheter was necessary to achieve satisfactory results with extracorporeal shock-wave lithotripsy (ESWL) for a stone in the ureter. METHOD: A retrospective review of 1,712 single ureteral stones treated in the ureter by ESWL using Dornier HM3 and Medstone STS lithotriptors was performed, 1,425 with a stent and 287 without a stent (in situ). Statistical analysis was performed using the chi-square test to determine the p value. RESULTS: The stone site, size, and treatment parameters (average shocks, kV, and estimated radiation to the patient) were similar in both groups. The retreatment rate, post-ESWL secondary procedure rate, and stone-free rate were 5 percent, 5 percent, and 79 percent, respectively, with a stent and 6 percent, 9 percent, and 79 percent, respectively, without a stent. CONCLUSION: The results of ESWL for single ureteral stones were similar with or without a stent, making the presence of a ureteral stent unnecessary.

Extracorporeal shock-wave lithotripsy for stones in middle third of ureter (overlying pelvic bone).

OBJECTIVE: To compare the results of using Dornier HM3 and Medstone STS lithotriptors to treat a ureteral stone overlying the pelvic bone (mid third of ureter) requiring the patient to be in the prone position. METHOD: The ease of use with each lithotriptor was evaluated and a retrospective review of the results using a Dornier HM3 in 53 patients and a Medstone STS in 143 patients was performed. The chi-square test was used to determine statistical difference. RESULTS: With single stones, the re-treatment rate, the post-ESWL secondary procedure rate, and the stone-free rate were 6 percent, 13 percent, and 75 percent, respectively, with the Dornier, and 6 percent, 8 percent, and 80 percent, respectively, with the Medstone. There was no statistically significant difference between these outcome results (p > 0.05). CONCLUSION: The prone position was difficult to achieve with the Dornier HM3, while the Medstone STS, a tubeless lithotriptor, allowed easy positioning of the patient in the prone position on its flat table. Satisfactory results were achieved using either machine.

Renal function after extracorporeal shock wave lithotripsy to a solitary kidney.

Studying renal function in patients with a solitary kidney undergoing SWL eliminates the compensatory effects of an untreated contralateral kidney and thus indicates any loss of function in the treated kidney. In 17 patients with a preoperative serum creatinine clearance of 1.5 mg/dl or less who underwent SWL to a solitary kidney, the glomerular filtration rate (GFR) was calculated by the formula of Cockcroft and Gault, which correlates significantly with measured creatinine clearance. A change of > or = 20% in the GFR was considered a clinically significant deterioration of renal function. In 12 patients with < 24 months' follow-up (mean 7.3 months) after SWL, there was no change in the estimated GFR, whereas 5 patients with > 24 months' follow-up (mean 36 months) had an average 22% reduction in the estimated GFR. This long-term effect is similar to the 29% long-term reduction in renal function recorded after percutaneous nephrolithotomy in solitary kidneys. Multiple stones, higher numbers of shock waves, and repeated SWL sessions correlated with decreases in GFR, but none of the differences was statistically significant. Like percutaneous nephrolithotomy, SWL results in a clinically significant long-term reduction in renal function.

Extracorporeal shock wave lithotripsy induced stimulation of the obturator nerve.

Extracorporeal shock wave lithotripsy to a left lower third ureteral calculus, 1.4 x 0.9 cm. large, using an unmodified Dornier HM3* lithotriptor with the patient in the sitting position produced thigh adductor movement with each shock. The procedure was terminated. Extracorporeal shock wave lithotripsy was performed uneventfully 1 week later using a Medstone STS lithotriptor with the patient in the supine position. We believe that the sitting position caused increased intra-abdominal pressure in the pelvis resulting in apposition of the ureteral segment containing the calculus to the obturator nerve, which was included either in the second focal point or in the extended shock path of the Dornier HM3 unit.

Perirenal extravasation with blunt trauma from rupture of a calyceal fornix.

Perirenal extravasation of urine with an intact renal parenchyma and with dye visualized in the ureter was seen on an excretory urogram (IVP) and computed tomographic (CT) scan in two patients (bilateral in one) with multiple injuries following blunt trauma. Expectant management with no invasive procedures resulted in disappearance of the extravasation within 3 to 5 days. Traumatic rupture of a calyceal fornix is thought to be the cause of the extravasation similar to the perirenal extravasation seen with renal colic from a ureteral calculus.

Extracorporeal shock wave lithotripsy in morbidly obese patients.

Management of urolithiasis in morbidly obese patients is usually associated with higher morbidity and mortality compared to nonobese patients. In morbidly obese patients, since the kidney and stone are at a considerable distance from the skin (compared to nonobese patients), difficulty may be encountered in positioning the patient so that the stone is situated at the F2 focal point of the lithotriptor. Using various aids, such as the extended shock pathway and abdominal compression, we treated 81 patients weighing more than 300 pounds using the Medstone STS tubless second generation lithotriptor. The stone-free rate at 3 months or longer was 68%, with another 10% having asymptomatic fragments of 4 mm. or less in diameter. Thus, a clinical stone-free rate of 78% was achieved. The retreatment rate was 11% and the post-lithotripsy secondary procedures rate was 3%. Since these results are comparable to those obtained when treating patients less than 300 pounds, extracorporeal shock wave lithotripsy can be used successfully to treat urolithiasis in morbidly obese patients.

Extracorporeal shock wave lithotripsy for calcified ureteral stent.

Calcification of a ureteral stent has been an unusual complication of long-term stent use for bypassing ureteral obstruction or after surgical repair. Open or percutaneous procedures have usually been required to remove the calcification before the stent can be extracted. We report six cases of calcified ureteral stents successfully managed by extracorporeal shock wave lithotripsy (SWL) followed by cystoscopic extraction, thus avoiding open or percutaneous procedures.

Traumatic dislocation of testes and bladder rupture.

Traumatic dislocation of the testes with bladder rupture occurred in 2 multiply injured patients with pelvic fracture. One had a history of retractile testes and the other of previous testicular dislocation. Surgical correction was performed after closed reduction failed. These injuries must be recognized and treated promptly to maximize the likelihood of testicular salvage. If early intervention is not possible, duplex ultrasonography and pulsed Doppler analysis are the optional valuative studies.