A S Cass

Hennepin County Medical Center, Minneapolis, Minnesota, United States

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Publications (112)

  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Mar 1996 · Journal of Endourology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Apr 1995 · The Journal of Urology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Jan 1995 · Journal of Endourology
  • Alexander S. Cass · John E. Heller
    [Show abstract] [Hide abstract] ABSTRACT: When pull on a stone basket enclosing a distal ureteral stone met marked resistance and endoscopic lithotripsy failed, extracorporeal shock wave lithotripsy was used to fragment the entrapped stone in the ureter and allowed successful removal of the basket with the enclosed fragments.
    Article · May 1994 · Urology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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. 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. 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. The results of ESWL for single ureteral stones were similar with or without a stent, making the presence of a ureteral stent unnecessary.
    Article · Mar 1994 · Urology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Feb 1994 · Journal of Endourology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: 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. 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. 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). 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.
    Article · Feb 1994 · Urology
  • Alexander S. Cass · Joe Y. Lee · Carl S. Smith
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Aug 1993 · The Journal of trauma
  • Joe Y. Lee · Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: One of the most important advances in trauma to the lower urinary and genital tracts has been the increased use of imaging techniques in its diagnosis and treatment. Computed tomography has been used in the diagnosis of bladder rupture and magnetic resonance imaging and ultrasonography in the diagnosis of post-traumatic urethral strictures. The treatment of post-traumatic urethral strictures by endoscopic urethroplasty has been facilitated by ultrasonography and fluoroscopy and ultrasonography has helped with blunt testicular injury in deciding surgery or observation. (C) Lippincott-Raven Publishers.
    Article · Jun 1993 · Current Opinion in Urology
  • A S Cass
    Article · May 1993 · British Journal of Urology
  • A S Cass · P Kavaney · L Levine · [...] · J Wolpert
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Mar 1993 · Journal of Endourology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: A case report of an acute severe genital infection simulating Fournier's gangrene was subsequently found to be caused by chickenpox.
    Article · Feb 1993 · Urology
  • J.Y. Lee · A.S. Cass · J.M. Streitz
    [Show abstract] [Hide abstract] ABSTRACT: 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.
    Article · Jan 1993 · Urology
  • A.S. CASS · W. BROOKER · E. DUTHOY · [...] · K.J. WHANG
    [Show abstract] [Hide abstract] ABSTRACT: Of 6765 patients having extracorporeal shock wave lithotripsy (SWL) with either a Dornier HM3 or a Medstone STS lithotripter to 7381 kidneys, 7 (0.1 %) developed clinically significant renal hemorrhage diagnosed by persistent pain, increasing hematuria, or a drop in hemoglobin in excess of 2 g/ml and confirmed by retrograde pyelography or ultrasound or CT scanning. Blood transfusion was required in one patient, and all seven patients were managed expectantly, with one patient having an unsuccessful attempt at percutaneous drainage of suspected infection of the hematoma at 4 weeks post-SWL. Pre-existing hypertension was present in three patients. Aspirin intake was present in four patients, and abnormal platelet aggregation studies were present in one of these patients 7 days after ceasing aspirin intake. It is important that patients be specifically questioned regarding aspirin intake, as some patients do not regard aspirin as a medication. Shock wave lithotripsy should be performed no earlier than 2 weeks after cessation of aspirin intake.
    Article · Dec 1992 · Journal of Endourology
  • A S Cass · JY Lee · H Aliabadi
    [Show abstract] [Hide abstract] ABSTRACT: A total of 12 patients with urinary diversions had calculi in 15 kidneys managed initially by extracorporeal shock wave lithotripsy (ESWL) in 12 kidneys and percutaneous nephrolithotripsy in 3. After 15 treatments with ESWL only 3 of the 12 kidneys (25%) became stone-free. Endoscopic procedures were used in 5 kidneys with fragments remaining after ESWL, and comprised percutaneous ultrasound lithotripsy in 2 and transstomal retrograde manipulations in 3. The 3 initial and 5 subsequent endoscopic procedures resulted in 6 of the 8 kidneys (75%) being stone-free. The poor results with ESWL are due to preexisting dilated upper urinary tracts and to immobility in obese myelomeningocele patients. Endoscopic procedures are the preferred method of treatment in these patients.
    Article · Oct 1992 · The Journal of Urology
  • A S Cass
    [Show abstract] [Hide abstract] ABSTRACT: Second generation tubless lithotriptors allow for easy prone positioning of patients, resulting in increased use of extracorporeal shock wave lithotripsy (ESWL) for calculi in the ureter, especially in the mid and lower third portions. The 3-month stone-free rate with single stones using a Dornier HM3 and a Medstone STS lithotriptor in the upper ureter was 79% (316 patients) and 81% (188), respectively, while in the mid ureter it was 60% (20 patients) and 81% (32), respectively, and in the lower ureter it was 80% (5 patients) and 85% (26), respectively. The retreatment rate with single stones using the Dornier HM3 and the Medstone STS devices was 5% and 4%, respectively, in the upper ureter, 13% and 12%, respectively, in the mid ureter, and 0% and 5%, respectively, in the lower ureter. The second procedure rate after ESWL with single stones using the Dornier HM3 and the Medstone STS units was 6% and 6%, respectively, in the upper ureter, 15% and 16%, respectively, in the mid ureter, and 0% and 17%, respectively, in the lower ureter. Expectant management is still an acceptable method to treat small ureteral stones, and it is questionable whether ESWL is the appropriate treatment for lower third ureteral stones compared to equally effective and less expensive ureteroscopy.
    Article · Jul 1992 · The Journal of Urology
  • Alexander S. Cass
    [Show abstract] [Hide abstract] ABSTRACT: We reviewed the results of ureteral stent use with extracorporeal shock-wave lithotripsy (ESWL) in 3,096 patients with renal calculi less than 3 cm in diameter. The 2,595 patients with indwelling ureteral stents required lower total power (shocks x voltage) and less radiation and had a lower secondary procedure rate but a higher retreatment rate than the 501 patients without stents. However, the only statistically significant difference was in the average radiation dose in patients with or without stents and single stones no larger than 10 mm (16 vs. 18 rad). The hospital stay was one day or less in 98 percent of the patients in both groups. With an 80 percent follow-up rate at three months indwelling ureteral stents were associated with a higher stone-free rate in patients with a single stone but a lower stone-free rate in patients with multiple stones, compared with those treated without a stent. An indwelling ureteral stent may result in urinary frequency and bladder discomfort in some patients, and with no statistical difference in the results with or without a ureteral stent it is questionable whether or not the high use of an indwelling ureteral stent is justified in patients admitted for one day or less.
    Article · Jun 1992 · Urology
  • A S Cass · P B Kavaney · C L Smith
    [Show abstract] [Hide abstract] ABSTRACT: Multiple large cystine stones formed on an indwelling ureteral stent used in the medical management of a 12-year-old boy with obstructing renal stones and cystinuria. Extracorporeal shock wave lithotripsy fragmented the cystine stones and allowed for extraction of the stent by cystoscopy.
    Article · May 1992 · The Journal of Urology
  • JY Lee · A S Cass
    [Show abstract] [Hide abstract] ABSTRACT: We report spontaneous bladder and uterine rupture in a patient undergoing oxytocin augmented labor while under epidural anesthesia after a previous cesarean section. The presenting signs were gross hematuria at placement of an indwelling catheter and fetal distress. Cesarean section produced a healthy newborn. The patient recovered satisfactorily after subtotal hysterectomy, bladder repair and transfusion.
    Article · Apr 1992 · The Journal of Urology
  • A S Cass
    [Show abstract] [Hide abstract] ABSTRACT: The current practice for the management of upper ureteral stones is to push the stone back into the renal pelvis before extracorporeal shock wave lithotripsy (ESWL*). The results in 903 patients with an upper third ureteral stone pushed back before ESWL were compared to those of 815 with an upper third ureteral stone treated by ESWL in situ with a ureteral stent bypassing the stone. The stone size in the in situ group was larger than in the push back group. More shocks at a higher kilovoltage were required to treat the in situ group. The retreatment rate and post-ESWL secondary procedure rate for the push back group with single stones were 4% and 1.5%, respectively, compared to 5% and 7.5%, respectively, for the in situ group. The stone-free rate with single stones at 3 months was 73% in the push back group and 79% in the in situ group. There appears to be little advantage in manipulating a ureteral stone into the kidney (push back) before treatment by ESWL.
    Article · Mar 1992 · The Journal of Urology