Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less.

PURPOSE: The optimal management of lower pole renal calculi is controversial. We compared shock wave lithotripsy (SWL) and ureteroscopy (URS) for the treatment of patients with small lower pole stones in a prospective, randomized, multicenter trial. MATERIALS AND METHODS: A total of 78 patients with 1 cm or less isolated lower pole stones were randomized to SWL or URS. The primary outcome measure was stone-free rate on noncontrast computerized tomography at 3 months. Secondary outcome parameters were length of stay, complication rates, need for secondary procedures and patient derived quality of life measures. RESULTS: A total of 67 patients randomized to SWL (32) or URS (35) completed treatment. The 2 groups were comparable with respect to age, sex, body mass index, side treated and stone surface area. Operative time was significantly shorter for SWL than URS (66 vs 90 minutes). At 3 months of followup 26 and 32 patients who underwent SWL and URS had radiographic followup that demonstrated a stone-free rate of 35% and 50%, respectively (p not significant). Intraoperative complications occurred in 1 SWL case (unable to target stone) and in 7 URS cases (failed access in 5 and perforation in 2), while postoperative complications occurred in 7 SWL and 7 URS cases. Patient derived quality of life measures favored SWL. CONCLUSIONS: This study failed to demonstrate a statistically significant difference in stone-free rates between SWL and URS for the treatment of small lower pole renal calculi. However, SWL was associated with greater patient acceptance and shorter convalescence.

A prospective, randomized, double-blinded placebo-controlled comparison of extended release oxybutynin versus phenazopyridine for the management of postoperative ureteral stent discomfort.

OBJECTIVES: Ureteral stents commonly cause lower urinary tract and flank discomfort. We evaluated the use of extended release oxybutynin versus phenazopyridine versus placebo for the management of ureteral stent discomfort after ureteroscopy. METHODS: Each of 60 patients who received a unilateral stent after ureteroscopy was given a blister pack containing 21 unmarked capsules of either extended release oxybutynin 10 mg, phenazopyridine 200 mg, or placebo in a prospective, randomized, and double-blinded fashion. Patients were instructed to take 1 capsule 3 times daily immediately after the procedure. Patients were given 50 tablets of oral narcotic to be taken as needed. Patients reported bothersome scores for flank pain, suprapubic pain, urinary frequency, urgency, dysuria, and hematuria on postoperative day 1, day 2, and the day of stent removal. Narcotic use was also recorded. RESULTS: Eight patients were excluded from the analysis for stent migration necessitating early removal (1), uncontrollable pain (1), failure to complete blister pack (4), and inability to contact for follow-up surveys (2). There was no difference in bothersome score among the groups for flank pain, suprapubic pain, urinary frequency, urgency, and dysuria. The phenazopyridine group reported less hematuria on postoperative day 1 when compared with placebo, which was statistically significant. The oxybutynin group required fewer narcotics, but this finding was not statistically significant. CONCLUSIONS: Although this study failed to show a significant difference in bothersome scores among the groups, the small sample size precludes definitive conclusion. Future studies pooling these data will determine the overall treatment effect and the optimal management of ureteral stent morbidity.

Medical management of common urinary calculi.

Nephrolithiasis is a common condition affecting nearly 5 percent of U.S. men and women during their lifetimes. Recurrent calculi can be prevented in most patients by the use of a simplified evaluation, reasonable dietary and fluid recommendations, and directed pharmacologic intervention. Serum studies and 24-hour urine collections are the mainstays of metabolic investigation and usually are warranted in patients with recurrent calculi. Although some stones are the result of inherited conditions, most result from a complex interaction between diet, fluid habits, and genetic predisposition. Calcium-sparing diuretics such as thiazides often are used to treat hypercalciuria. Citrate medications increase levels of this naturally occurring stone inhibitor. Allopurinol can be helpful in patients with hyperuricosuria, and urease inhibitors can help break the cycle of infectious calculi. Aggressive fluid intake and moderated intake of salt, calcium, and meat are recommended for most patients.

Metabolic abnormalities associated with calyceal diverticular stones.

OBJECTIVE: To review the metabolic analyses of patients with calyceal diverticular stones who had surgical treatment of their calculi and to examine the effect of selective medical therapy on stone recurrence, as recent reports suggest that metabolic abnormalities contribute to stone development. PATIENTS AND METHODS: In all, 37 patients who had endoscopic treatment of symptomatic calyceal diverticular calculi were retrospectively reviewed. Stone composition and initial 24-h urine collections (24-h urinary volumes, pH, calcium, sodium, uric acid, oxalate, citrate, and the number of abnormalities/patient per collection) were compared with 20 randomly selected stone-forming patients (controls) with no known anatomical abnormalities. Stone formation rates before and after the start of medical therapy were calculated in the patients available for follow-up. RESULTS: Twelve of the diverticulum patients (five men and seven women) had complete 24-h urine collections, all of whom had at least one metabolic abnormality. Seven patients had hypercalciuria, four had hyperuricosuria and three had mild hyperoxaluria. The most common abnormality was a low urine volume; 11 of the 12 patients had urine volumes of <2000 mL/day (range 350-1950). Ten patients had hypocitraturia in at least one of the two 24-h urine samples; seven had low urinary citrate levels (172-553 mg/day) on both samples. The findings were similar in the control group. The diverticulum patients had 3.1 abnormalities/patient, and the controls had 2.9 abnormalities/patient (P > 0.05). No patients had gouty diathesis and none developed cystine stones. Stone analyses were similar in the two groups; both developed either calcium oxalate or mixed calcium oxalate/calcium phosphate stones. Six patients were followed for a mean of 23.1 months while on selective medical therapy; only one passed any additional stones, thought to be existing calculi, for a remission rate of five of six (83%). CONCLUSIONS: All patients with symptomatic calyceal diverticular stones who had comprehensive metabolic evaluation had metabolic abnormalities. There were similar abnormalities in the control random stone-formers. The abnormalities were corrected with selective medical therapy, as shown by the high remission rate. We recommend that, for patients with symptomatic calyceal diverticular calculi, a metabolic evaluation should be considered to determine stone forming risk factors.

Prospective, randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less.

PURPOSE: The optimal management of lower pole renal calculi is controversial. We compared shock wave lithotripsy (SWL) and ureteroscopy (URS) for the treatment of patients with small lower pole stones in a prospective, randomized, multicenter trial. MATERIALS AND METHODS: A total of 78 patients with 1 cm or less isolated lower pole stones were randomized to SWL or URS. The primary outcome measure was stone-free rate on noncontrast computerized tomography at 3 months. Secondary outcome parameters were length of stay, complication rates, need for secondary procedures and patient derived quality of life measures. RESULTS: A total of 67 patients randomized to SWL (32) or URS (35) completed treatment. The 2 groups were comparable with respect to age, sex, body mass index, side treated and stone surface area. Operative time was significantly shorter for SWL than URS (66 vs 90 minutes). At 3 months of followup 26 and 32 patients who underwent SWL and URS had radiographic followup that demonstrated a stone-free rate of 35% and 50%, respectively (p not significant). Intraoperative complications occurred in 1 SWL case (unable to target stone) and in 7 URS cases (failed access in 5 and perforation in 2), while postoperative complications occurred in 7 SWL and 7 URS cases. Patient derived quality of life measures favored SWL. CONCLUSIONS: This study failed to demonstrate a statistically significant difference in stone-free rates between SWL and URS for the treatment of small lower pole renal calculi. However, SWL was associated with greater patient acceptance and shorter convalescence.

PlasmaKinetic bipolar vessel sealing: burst pressures and thermal spread in an animal model.

BACKGROUND AND PURPOSE: Laparoscopic bipolar instruments are commonly employed to cauterize and divide tissue. A next-generation bipolar device has been developed that employs vapor pulse coagulation energy. We assessed the vessel-sealing capability of this device and quantified thermal spread during application. MATERIALS AND METHODS: Bilateral laparoscopic nephrectomy was performed on six common swine >25 kg. Five-millimeter clips and surgical staplers (US Surgical, Norwalk, CT) were utilized to perform nephrectomy on one side, while the Gyrus PlasmaKinetic bipolar device (Minneapolis, MN) was employed for the contralateral nephrectomy. Vessel-sealing capabilities were assessed via burst-pressure studies. The extent of thermal spread was measured after tissue fixation and hematoxylin and eosin staining. RESULTS: Surgical clips/vascular staplers adequately controlled/sealed renal hilar vessels with burst pressures nearing 300 mm Hg. The Gyrus bipolar device reliably sealed and divided renal arteries

Laparoscopic hand-assisted nephrectomy for crossed fused ectopia with polycystic kidney disease.

Polycystic kidney disease occurring in individuals with crossed fused renal ectopia is an extremely rare occurrence. The treatment of individuals with this condition is a unique surgical challenge for the operating physician. Today's advances in laparoscopic techniques provide us with new and innovative ways of performing complex procedures while subjecting patients to relatively minimal surgical trauma. We describe the laparoscopic removal of a severely diseased polycystic crossed fused kidney.

Adrenergic regulation of salt and fluid secretion in human medullary collecting duct cells.

Transepithelial salt and fluid secretion mediated by cAMP in initial inner medullary collecting ducts (IMCDi) may be important for making final adjustments to urine composition. We examined in primary cultures of human IMCDi cells the effects of adrenergic receptor (AR) agonists and antagonists on intracellular cAMP levels, short-circuit current (I(SC)), and fluid secretion. Epinephrine (1 microM), norepinephrine (1 microM), and isoproterenol (10 nM) individually increased intracellular cAMP levels 57-, 2-, and 25-fold, respectively, and stimulated I(SC) 3.3-, 2.9-, and 3.4-fold, respectively. beta-AR activation increased net fluid secretion by cultured human IMCDi cell monolayers from 0.09 +/- 0.04 to 0.26 +/- 0.05 microl x h(-1) x cm(-2) and freshly isolated rat IMCDi from 0.02 +/- 0.01 to 0.09 +/- 0.02 nl x h(-1) x mm(-1). In monolayers, these effects were eliminated by blocking beta2-AR, but not beta1-AR. Activation of alpha2-AR with guanabenz inhibited isoproterenol-induced I(SC) by 37% in human IMCDi monolayers and fluid secretion by 91% in rat IMCDi. Immunohistochemistry of human medullary tissue sections revealed greater expression of beta2-AR than beta1-AR; beta2-AR was localized to the basolateral membranes of human IMCDi. Immunoblots identified alpha2A-AR and alpha2B-AR in cultured human IMCDi cell monolayers. We conclude that 1) catecholamines stimulate cAMP-dependent anion and fluid secretion by IMCDi cells primarily through beta2-AR activation and 2) alpha2-AR activation attenuates cAMP-dependent anion secretion.

Adrenal pseudocyst: a unique case with adrenal renal fusion, mimicking a cystic renal mass.

We describe an unusual adrenal pseudocyst mimicking radiologically and clinically renal mass. The cyst measured 12 cm in diameter and had a fibrotic external envelope that was fused with the renal capsule. The possible diagnostic pitfalls encountered in this case are discussed.

Internet based multi-institutional clinical research: a convenient and secure option.

PURPOSE: As randomized, prospective trials have become an integral part of clinical research, multi-institutional, collaborative research has become a necessity. However, it may be cumbersome for participants at remote facilities to participate because the submission and compilation of data and results are at times lengthy processes. Internet based clinical studies have been found to be a rapid, easily accessible, safe and secure method of performing multi-institutional trials. MATERIALS AND METHODS: The Internet was used at geographically distant medical centers to enroll patients into a multi-institutional, prospective, randomized trial for the management of lower pole renal calculi. The Clinical Research Web-based Information Center secure computer web based program (Simplified Clinical Data Systems, Amherst, New Hampshire) was established to input preliminary demographic and clinical data, randomize patients, and collect treatment and followup information without paper chart documentation. The primary investigators in the study were sent a questionnaire to determine the ease of use of this Internet based program. The results were tabulated. RESULTS: A total of 112 patients from 21 participating institutions were randomized into the secure web site for inclusion into a lower pole renal stone clinical trial. Of the investigators 64% responded to the questionnaire. The majority of those having enrolled patients into the study reported no difficulties or only minimal difficulties in navigating the web site. Moreover, investigators from remote locations throughout North America described the improved convenience, rapid transmission of information, and ability to review and update patient data as benefits of enrolling patients using the Internet. The Internet based system also permits the prompt compilation of data at the host research site for performing interim data assessments and eventually the final analysis. CONCLUSIONS: A web based data collection center allows for large, multi-institutional trials to be done with unprecedented accuracy and efficiency. Through centralization of data capture, and real-time study monitoring and data analysis the system removes these responsibilities from those at individual test sites, permitting investigators to concentrate instead on other aspects of the study and its progress. State-of-the-art security protects all information to ensure confidentiality. The Internet may prove to be an invaluable tool in the future of clinical research.

Bilateral renal calculi: assessment of staged v synchronous percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: Percutaneous stone removal has replaced open renal surgery and has become the treatment of choice for large or complex renal calculi. However, patients with large bilateral stone burdens still present a challenge. Simultaneous bilateral percutaneous nephrolithotomy (PCNL) has been demonstrated to be a well-tolerated, safe, cost-effective, and expeditious treatment. We present what is, to our knowledge, the first large retrospective series comparing synchronous and asynchronous bilateral PCNL. PATIENTS AND METHODS: A chart review was performed on 26 patients undergoing 57 PCNLs for bilateral renal calculi over a 7-year period. Seven patients received synchronous PCNL (same anesthesia; Group 1), and 19 patients underwent asynchronous PNL (procedures separated by 1-3 months; Group 2). Complete surgical and hospital records were available on all patients. The average stone burden for Group 1 was 8.03 cm(2) on the left and 9.18 cm(2) on the right v 10.1 cm(2) on the left and 14.23 cm(2) on the right for Group 2 (P> 0.05). Variables of interest included anesthesia time, operative time, blood loss, transfusion rates, length of hospital stay, and complication rates. Each variable was evaluated per operation and per renal unit. Follow-up imaging with stone assessment was available on 20 patients. RESULTS: Group 1 required 1.14 access tracts per renal unit to attempt complete clearance of the targeted stones v 1.88 tracts per renal unit in Group 2 (P> 0.05). The average operative time per renal unit was significantly less in Group 1 (83 minutes) than in Group 2 (168.5 minutes) (P< 0.0001), as was blood loss (178.5 mL v 307.4 mL, respectively; P= 0.02). However, blood loss per operation was similar at 357 mL in Group 1 and 282 mL in Group 2. Comparable transfusion rates of 28.6% and 36.8%, respectively, were noted. Forty percent of the patients in Group 1 were completely stone free compared with 36% of the patients in Group 2; however, an additional 50% and 57%, respectively, had residual stone burden <4 mm (P> 0.05). Complications occurred in 2 of 7 operations (28%) in Group 1 and 8 of 42 operations (19%) in Group 2. The total length of hospital stay was nearly doubled for patients undergoing staged PCNL (P= 0.0005). CONCLUSIONS: These results demonstrate similar stone-free rates, blood loss per operation, and transfusion rates for simultaneous and staged bilateral PCNL. The reduced total operative time, hospital stay, and total blood loss, along with the requirement for only one anesthesia, makes synchronous bilateral PCNL an attractive option for select individuals. However, in patients with larger, less easily accessible stones, excessive bleeding may be encountered more frequently on the first side, thereby delaying management of the second side to a later date. Synchronous bilateral PCNL should be considered in patients in whom the first stage of stone removal is accomplished quickly and safely.

Ureteroscopy for benign hematuria.

Any patient presenting with hematuria of unknown origin should undergo a thorough history, physical examination, and laboratory and radiographic work-up. All attempts should be made to exclude malignancy. Renal hemangiomas are the most likely cause of chronic benign hematuria, particularly in young patients. In the past these lesions were treated with complete or partial nephrectomy. With the availability of small, flexible ureteroscopes capable of primary and secondary deflection, ureterorenoscopy has become an excellent means of diagnosing and treating these lesions. Various instruments--including an electrocautery probe, Nd:YAG laser, and Holmium:YAG laser--have been used with similar results.

Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation.

BACKGROUND AND PURPOSE: New-generation flexible ureteroscopes allow the management of proximal ureteral and intrarenal pathology with high success rates, including complete removal of ureteral and renal calculi. One problem is that the irrigation pressures generated within the collecting system can be significantly elevated, as evidenced by pyelovenous and pyelolymphatic backflow seen during retrograde pyelography. We sought to determine if the ureteral access sheath (UAS) can offer protection from high intrarenal pressures attained during routine ureteroscopic stone surgery. PATIENTS AND METHODS: Five patients (average age 72.6 years) evaluated in the emergency department for obstructing calculi underwent percutaneous nephrostomy (PCN) tube placement to decompress their collecting systems. The indications for PCN tube placement were obstructive renal failure (N=1), urosepsis (N=2), and obstruction with uncontrolled pain and elevated white blood cell counts (N=2). Flexible ureteroscopy was subsequently performed with and without the aid of the UAS while pressures were measured via the nephrostomy tube connected to a pressure transducer. Pressures were recorded at baseline and in the distal, mid, and proximal ureter and renal pelvis, first without the UAS, and then with the UAS in place. RESULTS: The average baseline pressure within the collecting system was 13.6 mm Hg. The mean intrarenal pressure with the ureteroscope in the distal ureter without the UAS was 60 mm Hg and with the UAS was 15 mm Hg. With the ureteroscope in the midureter, the pressures were 65.6 and 17.5 mm Hg, respectively; with the ureteroscope in the proximal ureter 79.2 and 24 mm Hg, and with the ureteroscope in the renal pelvis 94.4 and 40.6 mm Hg, respectively. All differences at each location were statistically significant (P<0.008). Compared with baseline, all pressures measured without the UAS were significantly greater, but only pressures recorded in the proximal ureter and renal pelvis after UAS insertion were significantly higher (P<0.03). CONCLUSIONS: The irrigation pressures transmitted to the renal pelvis and subsequently to the parenchyma are significantly greater during routine URS without the use of the UAS. The access sheath is potentially protective against pyelovenous and pyelolymphatic backflow, with clinical implications for the ureteroscopic management of upper-tract transitional cell carcinoma, struvite stones, or calculi associated with urinary tract infection.

Hand-assisted laparoscopic nephrectomy: the transfer of experience to a new academic center.

BACKGROUND AND PURPOSE: Hand-assisted laparoscopic nephrectomy (HALN) has become widely used for the management of localized renal masses and for simple nephrectomy [corrected] Centers of excellence have slowly disseminated this surgical approach throughout academic institutions and private practices. The transfer of this technique to inexperienced surgeons and centers has not been well studied. We examined our outcomes for HALN with an experienced surgeon (DMA) [corrected] at a new academic center. We also examined the effectiveness of the transfer of these techniques as trainees go out into practice [corrected] PATIENTS AND METHODS: A total of 85 hand-assisted laparoscopy procedures were performed between September 2001 and August 2003 of which 61 were HALN. Four fellows and eight chief residents, under the guidance of one attending surgeon (DMA), performed all HALN procedures. Parameters measured included patient age, ASA score, body mass index, operative time, estimated blood loss, number of trocars used, time to oral intake, analgesics required, length of stay, complications, and tumor size. The average patient age was 57.4 years (range 26-87 years) and the mean ASA score 2.5 (1-4). The mean BMI was 28.3 (range 20-46) [corrected] There was a slight predominance of right-sided lesions. In addition to evaluating our early results with HALN, a questionnaire was sent to all graduates of our program starting 2 years prior to the arrival of DMA to assess the application of laparoscopy to their practices [corrected] RESULTS: All cases were completed without open conversion. The total operative time averaged 184 [corrected] minutes (range 67-257 [corrected] minutes), with 80% of patients requiring two trocars. The average blood loss was 136 [corrected] ml (range 25-700 mL), but only one patient required transfusion postoperatively [corrected] The mean time to oral intake was 17.1 hours (range 1.5-240 hours), the average length of stay was 4.3 days (range 1-28 days), and total narcotic requirements averaged 111 mg of morphine sulfate equivalents (range 6.7-519 mg). Sixty-six percent of the procedures were performed for malignancy. The average tumor size in these cases was 3.9 cm (range 1-12 cm). There was one death, in an 80-year-old patient who had a bowel injury necessitating re-exploration and bowel resection. This patient had a postoperative myocardial infarction and died. Two patients developed postoperative hernias at their hand-port site. Other significant [corrected] complications included diaphragmatic [corrected] injury (repaired laparoscopically), one [corrected] pulmonary embolus, two cases of pancreatitis, and one case of pneumonia. Three patients experienced postoperative ileus. Of the 20 graduates of this program since 2000, 4 were laparoscopic/endourology fellows, and 2 of the residents pursued fellowship training after graduating. Graduates of the year 2000 and 2001 represent surgeons who graduated prior to the arrival of DMA. Of those resident graduates who did not pursue fellowship, two of the seven surgeons who graduated prior to the arrival of DMA are performing laparoscopy. Both of these surgeons pursued formal postgraduate laparoscopic training. Six of the seven non-fellowship-trained residents who graduated since DMA's arrival are performing laparoscopy; the other is early in practice and intends to do so. None of these surgeons has pursued postgraduate training prior to performing laparoscopy in their practices [corrected] CONCLUSIONS: The HALN techniques can be transferred quickly and efficiently between [corrected]one center and [corrected] another under the guidance of an experienced surgeon. Operative times are acceptable, with complication rates comparable to [corrected] previously reported series. Our data show that exposure during residency markedly increases the likelihood that surgeons will carry the techniques into their practices [corrected]

Pain after percutaneous nephrolithotomy: impact of nephrostomy tube size.

BACKGROUND AND PURPOSE: Percutaneous nephrolithotomy (PCNL) is the procedure of choice for managing large renal calculi. Investigations have recently focused on reducing the morbidity of the procedure and improving postoperative patient comfort by using smaller endoscopic instruments. We sought to evaluate the effect of a smaller percutaneous drainage catheter on postoperative pain. PATIENTS AND METHODS: Thirty consecutive patients were randomized to receive either a 10F pigtail catheter or a 22F Councill-tip catheter for their percutaneous drainage after PCNL. The demographics were similar in the two groups, as was the rate of supracostal access (47% v 43%, respectively). Self-assessed analog pain scores were collected at 6 hours postoperatively as well as on the morning of the first and second postoperative days (POD). Total narcotic usage was tabulated using morphine equivalents. Complications, including the change from baseline hematocrit, were reviewed. RESULTS: There was no significant difference in the change in hematocrit (6.8 v 6.2 percentage points, respectively). Those patients with the smaller nephrostomy tube noted significantly lower pain scores at 6 hours (3.75 v 5.3; P=0.03). Although the pain scores were lower on POD 1 and 2 for the 10F catheter group, the difference was not statistically different (1.9 v 2.9 and 1.25 v 1.9, respectively; both P>0.05). The patients having the 10F catheter required fewer narcotics: 78 mg v 91 mg, although the difference was not statistically significant. CONCLUSION: The use of a small drainage catheter after PCNL is associated with lower pain scores in the immediate postoperative period, yet no statistically significant benefit to the patient with regard to comfort is demonstrated beyond 6 hours. In addition, there is a trend toward reduced narcotic requirements. Finally, there is no apparent increase in patient morbidity from the use of the smaller nephrostomy tubes.

Clinical efficacy of a combination pneumatic and ultrasonic lithotrite.

PURPOSE: A new combination pneumatic/ultrasonic intracorporeal lithotriptor has been developed for percutaneous applications. It combines the stone clearing efficiency of an ultrasonic device with the fragmentation strength of a pneumatic probe into a single handpiece. We present our early clinical experience with this device in a prospective, randomized comparison a combination pneumatic/ultrasound lithotrite and standard ultrasonic lithotripsy. MATERIALS AND METHODS: A total of 20 consecutive patients undergoing percutaneous nephrolithotomy for symptomatic calculi were randomized to receive stone fragmentation and removal using a standard ultrasonic device or a new combination pneumatic/ultrasonic unit. Stone location and burden were assessed before the operative procedure. The stone clearance rate in mm.2 per minute was calculated for the 2 devices. Complications and stone-free rates were compared in the 2 groups. RESULTS: There were no significant differences in stone location and composition in the 2 groups of patients. Average time required for complete stone clearance was considerably less for the combination device (21.1 versus 43.7 minutes, p = 0.036). The opposite was true for the average rate of stone clearance in mm.2 per minute, in that the standard ultrasonic device could clear 16.8 versus 39.5 mm.2 per minute for the combination unit (p = 0.028). Stone-free and complications rates were slightly superior for the combination device but it was likely attributable to patient factors. CONCLUSIONS: The combination pneumatic/ultrasonic lithotrite is capable of disintegrating and extracting stone material at a more rapid rate than standard ultrasonic devices. Moreover, stone-free and complication rates appear to be slightly superior with the combination unit. This new combination pneumatic/ultrasonic device appears to be efficacious and safe for removing large renal calculi.

Assessment of stricture formation with the ureteral access sheath.

OBJECTIVES: To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma. METHODS: Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients. RESULTS: The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor. CONCLUSIONS: The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.

Biochemical profile of stone-forming patients with diabetes mellitus.

OBJECTIVES: To test the hypothesis that stone-forming patients with type II diabetes (DM-II) have a high prevalence of uric acid (UA) stones and present with some of the biochemical features of gouty diathesis (GD). METHODS: The demographic and initial biochemical data from 59 stone-forming patients with DM-II (serum glucose greater than 126 mg/dL, no insulin therapy, older than 35 years of age) from Dallas, Texas and Durham, North Carolina were retrieved and compared with data from 58 patients with GD and 116 with hyperuricosuric calcium oxalate urolithiasis (HUCU) without DM. RESULTS: UA stones were detected in 33.9% of patients with DM-II compared with 6.2% of stone-forming patients without DM (P <0.001). Despite similar ingestion of alkali, the urinary pH in patients with DM-II and UA stones (n = 20) was low (pH = 5.5), as it is in patients with GD, and was significantly lower than in patients with HUCU. The urinary pH in patients with DM-II and calcium stones (n = 39) was intermediate between that in those with DM-II and UA stones and those with HUCU. However, both DM groups had fractional excretion of urate that was not depressed, as it is in those with GD, and was comparable to the value obtained in those with HUCU. The urinary content of undissociated UA was significantly higher, and the saturation of calcium phosphate (brushite) and sodium urate was significantly lower in those with DM-II and UA stones than in those with HUCU. CONCLUSIONS: Stone-forming patients with DM-II have a high prevalence of UA stones. Diabetic patients with UA stones share a key feature of those with GD, namely the passage of unusually acid urine, but not the low fractional excretion of urate.