In vitro assessment of a novel dual probe ultrasonic intracorporeal lithotriptor.

PURPOSE: The Cyberwand (Cybersonics, Erie, Pennsylvania) is a novel intracorporeal lithotrite that uses coaxial ultrasonic elements operating at 2 frequencies. We compared this device to the LithoClast(R) Ultra, which we previously noted is the most efficient commercially available intracorporeal lithotripsy device. MATERIALS AND METHODS: An in vitro test system was used to assess the efficiency of stone penetration for the Cyberwand and the LithoClast Ultra. The devices were mounted upright with the probe tip up in a modified irrigation sheath. A gypsum artificial stone was centered on the probe tip and a mass was placed atop the stone to provide a constant force. The manufacturer recommended setting was selected for the Cyberwand, while for the LithoClast Ultra a pneumatic frequency of 12 Hz with an ultrasonic power setting of 100% was selected, representing optimal settings in previous in vitro tests. The time required for complete stone penetration was measured. Differences in mean stone penetration times were compared using ANOVA. RESULTS: Mean +/- SD penetration time for the Cyberwand was significantly shorter than for the LithoClast Ultra (4.8 +/- 0.6 vs 8.1 +/- 0.6 seconds, p <0.0001). Neither device showed any difficulties with overheating, occlusion or another malfunction. CONCLUSIONS: Initial assessment using our hands-free in vitro test system, in which stone penetration time is not affected by operator bias, suggests that the Cyberwand is an efficient lithotrite. These promising results justify in vivo testing.

The pathogenesis of calyceal diverticular calculi.

Controversy exists over whether metabolic factors or urinary stasis predominate in the pathogenesis of calyceal diverticular calculi. We performed a study to better define the effects urinary stasis and metabolic abnormalities have in the pathogenesis of calyceal diverticular stones. Twenty-nine patients who underwent percutaneous treatment of calyceal diverticular calculi were studied. All patients underwent 24 h urine collection to evaluate metabolic risk factors. In three patients, urine was sampled directly from the diverticulum for metabolic studies. The urinary stone risk parameters of the patients with calyceal diverticular stones (Tic SF) were similar to those of a well-characterized cohort of calcium oxalate stone formers (CaOx SF). When compared to a group of normal people, the Tic SF and CaOx SF were significantly more hypercalciuric and their urine was significantly more supersaturated with calcium oxalate. Urine aspirated directly from the diverticulum had the lowest SSCaOx when compared to ipsilateral and contralateral renal pelves. The urinary risk profiles of patients with diverticular calculi are similar to those of CaOx SF, suggesting a metabolic etiology of diverticular stones. However, the SS CaOx of urine aspirated directly from the diverticula is significantly lower than that of the renal pelves; these data support the hypothesis that urinary stasis significantly contributes to the pathogenesis of calyceal diverticular calculi. Taken together, it seems likely that calyceal diverticular calculi arise from a combination of metabolic abnormalities and urinary stasis.

The camera phone: a novel aid in urologic practice.

OBJECTIVES: To describe a novel use of the camera phone for efficient, reliable, and cost-effective collection and transmission of medical data in the urologic setting. METHODS: We used camera phones (Verizon VGA and Sanyo-Sprint PCS) with a resolution of 640 x 480 pixels to capture images in the operating room, as well as in the outpatient clinic. Images were obtained directly from the monitor or the x-ray viewing box. These were then immediately transmitted to the office computer through a secure Internet connection. The images were then incorporated into operative and office notes, as needed. RESULTS: The images obtained with this method were of adequate quality for demonstration purposes, with the added advantage of allowing secure transmission and storage. The best-quality images were those obtained directly from the x-ray viewing box or from a liquid crystal display monitor. In addition, the images could be edited and labels added with the aid of the software that came with the camera phone. CONCLUSIONS: This method allows the acquisition of fair-quality digital images of surgical procedures and radiographic studies with simultaneous data transmission and storage for clinical documentation. The technology reduced costs and increased the efficiency of our practice considerably.

Changing composition of renal calculi in patients with neurogenic bladder.

PURPOSE: Renal calculi are a significant source of morbidity for patients with neurogenic bladder. Calculi from patients with NB have traditionally been composed primarily of struvite and carbonate apatite secondary to chronic urea-splitting bacteriuria. In the current era there have been great improvements in the urological rehabilitation of patients with NB. We defined the composition of renal calculi in a contemporary cohort of patients with NB due to spinal cord injury or myelomeningocele who underwent percutaneous nephrolithotomy. MATERIALS AND METHODS: We performed a retrospective evaluation of all patients with NB due to SCI or MM who underwent PNL between January 2002 and January 2005. RESULTS: A total of 32 patients with NB (14 with SCI, 18 with MM) underwent PNL in this period. Stones were infectious in etiology in 37.5% (12 struvite/carbonate apatite) and metabolic in 62.5% (1 uric acid, 2 calcium oxalate monohydrate, 2 brushite, 6 hydroxyapatite, 9 mixed hydroxyapatite/calcium oxalate). All patients with struvite calculi were infected with urea-splitting bacteria on preoperative urine culture. CONCLUSIONS: Patients with neurogenic bladder are traditionally thought to harbor infection related calculi. These data demonstrate that many contemporary patients will be found to have calculi of a metabolic etiology. Although patients with NB still have renal calculi, advances in urological treatment may have affected the composition of their calculi, as metabolic stones are becoming more commonly identified. When metabolic components are identified, stone activity may be attenuated with appropriate metabolic evaluation, pharmacological therapies and dietary modifications.

Endoscopic evidence of calculus attachment to Randall's plaque.

PURPOSE: It has been proposed that calcium oxalate calculi begin as small stones attached to the renal papillae at sites of Randall's plaque. However, no study has investigated the prevalence of attached stones in calcium oxalate stone formers or the relationship between stone attachment site and Randall's plaque. In this study we used endoscopic examination of renal papillae in stone formers undergoing percutaneous nephrolithotomy to investigate both issues. MATERIALS AND METHODS: Idiopathic calcium oxalate stone formers undergoing PNL for stone removal were enrolled in this study. Multiple papillae were examined and images were recorded by digital video. The presence or absence of papillary plaque and attached stones was noted, as was the site of stone attachment. RESULTS: In 23 patients, 24 kidneys and 172 renal papillae were examined. All kidneys were found to have papillary plaque and 11 of the patients had attached stones. Most papillae (91%) contained plaque. CONCLUSIONS: The prevalence of attached stones in calcium oxalate stone formers (48%) is greater than that previously reported for the general population. Attachment appears to be on Randall's plaque. The high prevalence of attached stones and the appearance of the attachment site are consistent with a mechanism of calcium oxalate stone formation in which stones begin as plaque overgrowth.

Percutaneous nephrolithotomy for ectopic kidneys: over, around, or through.

OBJECTIVES: The treatment of patients with complex urolithiasis in ectopic kidneys can be challenging. Because the location of an ectopic kidney can vary, each case requires a unique and, at times, unconventional approach. We reviewed the techniques we have developed to treat such patients, including laparoscopic-assisted tubeless, transhepatic, and transiliac percutaneous nephrolithotomy (PNL). METHODS: We performed a retrospective analysis of all patients with congenital pelvic kidneys who underwent PNL at our institution. Six patients underwent laparoscopic-assisted PNL, one underwent transiliac PNL, and one underwent transhepatic PNL. All laparoscopic-assisted procedures were performed tubeless, with an internalized ureteral stent placed at the conclusion of the procedure. RESULTS: All patients underwent successful PNL. On computed tomography, performed on the morning of postoperative day 1, all patients who underwent laparoscopic-assisted PNL were stone free. The patients who underwent transiliac PNL and transhepatic PNL required secondary procedures to attain a stone-free status. The mean length of hospitalization was 3 days for the laparoscopic-assisted cohort, 1 day for the transhepatic patient, and 3 days for the transiliac patient. CONCLUSIONS: For the patient with a large or complex stone burden in an ectopic kidney, laparoscopic-assisted PNL is the optimal treatment. Performing such a procedure tubeless may be associated with a reduced hospital stay. For those patients with a hostile peritoneal cavity owing to prior surgical exploration, consideration should be given to a more individualized approach.

Outcomes of hand-assisted laparoscopic nephrectomy in technically challenging cases.

OBJECTIVES: To evaluate the outcomes of hand-assisted laparoscopic nephrectomy in patients with significant complicating clinical factors. METHODS: We performed a retrospective review of 322 hand-assisted laparoscopic nephrectomy cases that were completed at a single institution from 1998 to 2004. Patients with a history of extensive abdominal surgery or prior procedures on the affected kidney, evidence of perirenal inflammation, renal lesions 10 cm or more in diameter, or level I renal vein thrombus were included. RESULTS: A total of 42 patients were included in this series. Of these, 16 patients had a lesion 10 cm or larger, 10 had a renal vein thrombus, and 10 had undergone prior major abdominal surgery. Many patients had more than one complicating factor. Another 6 patients had a history of prior renal procedures or chronic inflammatory processes involving the affected kidney. One Stage T4 renal tumor with paraspinous muscle invasion was successfully managed without conversion. The overall mean operative time and estimated blood loss was 235 minutes and 439 mL, respectively, with a mean hospital stay of 4 days. Four patients (9.5%) required open conversion (one renal hilar injury, two failure to progress, and one persistent bleeding from the renal fossa). Postoperative complications included pulmonary embolism in 1, ileus in 1, and chronic obstructive pulmonary disease exacerbation in 1 patient. One patient developed an incarcerated port site hernia requiring reoperation. CONCLUSIONS: Hand-assisted laparoscopic nephrectomy is an attractive minimally invasive option in the setting of significant complicating factors. This technique may facilitate the successful laparoscopic completion of these challenging cases with reasonable operative times, blood loss, and complication rates.

Holmium laser enucleation of the prostate for prostates of >125 mL.

OBJECTIVE: To examine a group of patients treated with holmium laser enucleation of the prostate (HoLEP) and with the bladder outlet obstructed by an exceptionally large (>125 mL) prostate, as such men are often not considered candidates for endoscopic treatments and historically have required open surgery. PATIENTS AND METHODS: We analysed retrospectively all patients with prostates of > 125 mL on transrectal ultrasonography (TRUS) who underwent HoLEP between January 2000 and January 2005. RESULTS: Eighty-six patients were identified; their mean (range) age was 72.6 (48-90) years and prostate volume 170.2 (125-309) mL. Their mean preoperative prostate-specific antigen (PSA) level was 9.82 ng/mL and preoperative American Urologic Association symptom score (AUA-SS) was 19.6. The mean operative duration and hospital stay were 128.1 min and 26.1 h, respectively. The mean weight of tissue enucleated was 140.2 g. At the 1-month follow-up the mean AUA-SS (63 men) was 8.4 and at 6 months (35 men) it was 6.4. The mean serum PSA level in 48 patients was 0.96 ng/mL, a reduction of 90%. TRUS measurements in 20 patients gave a mean prostate volume of 30.8 mL, a reduction of 82%. At the 1-year follow-up the mean AUA-SS of 22 patients was 5.1. CONCLUSIONS: The present report details the largest series of patients, with the largest mean prostate size, treated by any endoscopic surgical method. HoLEP may be the ideal treatment for men with prostates of > 125 mL with symptoms of bladder outlet obstruction.

Acute effects of percutaneous tract dilation on renal function and structure.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is performed on a routine basis for the rapid and efficient removal of large caliceal stones. After percutaneous puncture, rigid dilators or an inflatable balloon are used to dilate the nephrostomy tract to allow access to the collecting system for stone removal. Little is known of the acute impact of tract dilation procedures on renal function. MATERIALS AND METHODS: We compared renal hemodynamic and excretory function in female pigs immediately before and up to 5 hours after percutaneous nephrostomy (PCN) using sequential Amplatz dilators (N = 8) or Nephromax balloon inflation (N = 7) and control pigs with no PCN access (N = 8). We also examined renal function in patients undergoing PCNL. RESULTS: The two PCN procedures produced a renal lesion of comparable size and morphology, as well as similar changes in renal function. Glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion (U(Na)V) were significantly reduced in Amplatz- and Nephromax-treated kidneys throughout the 5-hour observation period, by about 50%, 60%, and 80%, respectively. In control pigs, GFR and RPF remained stable and U(Na)V declined progressively to about 50% of baseline over the course of the experiment. The contralateral kidney showed changes in renal function similar to those in the PCN-treated or control kidney in all three groups. A retrospective analysis of 196 adults with normal renal function who underwent unilateral PCNL using the Nephromax balloon dilator revealed a significant increase in serum creatinine of 0.14 mg/dL at 1 day. CONCLUSION: Both animal and human studies show that PCN is associated with an acute decline in renal function.

Holmium laser enucleation of the prostate for men with urinary retention.

PURPOSE: Holmium laser enucleation of the prostate (HoLEP) is an established procedure for the treatment of patients with benign prostatic hyperplasia. We performed a study to examine a group of patients in urinary retention treated by HoLEP. MATERIALS AND METHODS: A retrospective analysis of 164 consecutive patients with urinary retention who underwent HoLEP between January 2000 and August 2004 was performed. RESULTS: Mean patient age was 72.1 years (range 34 to 95). Mean duration of urinary retention was 28.9 days (range 2 to 365). Mean preoperative transrectal ultrasound measured prostate volume was 107.1 cc (range 5 to 242). Mean weight of resected tissue was 81.9 grams (range 2.5 to 271). Mean duration of postoperative catheterization and hospitalization was 22.5 hours (range 2 to 240) and 33.7 hours (range 2 to 144), respectively. All patients were able to void following treatment and remain catheter free. CONCLUSIONS: HoLEP is an effective treatment, with low morbidity, for patients with urinary retention. These results suggest that HoLEP may be the ideal treatment for men with urinary retention due to benign prostatic obstruction.

Change in serum prostate specific antigen concentration after holmium laser enucleation of the prostate: a marker for completeness of adenoma resection?

BACKGROUND AND PURPOSE: Holmium laser enucleation of the prostate (HoLEP) is a well-established technique for the treatment of benign prostatic hyperplasia (BPH). To date, changes in serum prostate specific antigen (PSA) after HoLEP have not been published. We hypothesized that HoLEP produces a diminution in PSA similar to that produced by the gold-standard therapies for BPH. To test this hypothesis, we have examined PSA data before and after HoLEP from two institutions performing high volumes of this procedure. PATIENTS AND METHODS: Between August 1998 and September 2004, 509 HoLEPs were performed at two institutions for which complete PSA data were available. Preoperative demographic and transrectal ultrasonography (TRUS) volume measurements were recorded; postoperative pathology and TRUS volume were obtained. Change in PSA as a function of the weight of prostate resected and the relation of preoperative TRUS volume to PSA was determined. RESULTS: The average weight of adenoma resected was 49.8 g (range 5-300 g) in the McGill group and 90.4 g (range 7.9-312 g) in the Methodist Hospital group. The mean decrease in PSA was 81.7% in the McGill group (range 6.0-1.1 ng/mL; P < 0.0001) and 86.0% in the Methodist Hospital group (range 8.6-1.2 ng/mL; P < 0.0001). Log transformed preoperative PSA correlated well with TRUS volume (r = 0.45), as did the weight of adenoma resected with absolute change in PSA (r = 0.38). The TRUS volume decreased significantly, from 111.9 cc to 26.5 cc, in the Methodist Hospital group (P < 0.0001). CONCLUSION: The HoLEP procedure produces a significant diminution in PSA that correlates well with the weight of adenoma resected. Measurement of PSA may be a useful tool for the objective assessment of ablative therapies for BPH, as the reduction in PSA corresponds well with the amount of adenoma removed.

Holmium laser enucleation of the prostate: a comparison of efficiency measures at two institutions.

BACKGROUND AND PURPOSE: Holmium laser enucleation of the prostate (HoLEP) is perceived to be technically difficult, time consuming, and inefficient. We assessed the efficiency of HoLEP by documenting the technical features of the procedure at two hospitals located on different continents. PATIENTS AND METHODS: A retrospective analysis of all patients who underwent HoLEP at the Methodist Hospital of Indiana and Tauranga Hospital in New Zealand was performed. A series of 40 patients from the Indiana cohort were pair-matched, by the weight of prostate tissue retrieved, with 40 patients from the New Zealand cohort. Enucleation time and morcellation time were compared in the two groups. RESULTS: The mean weight of the tissue retrieved from the Indiana cohort was 27.1 g and that from the New Zealand cohort was 22.9 g (P = 0.41). The mean enucleation times were 47.6 minutes and 29.2 minutes, respectively (P < 0.001). The mean morcellation times were 9.9 minutes and 7.7 minutes (P = 0.201). The mean rates of enucleation were 0.58 g/min and 0.71 g/min (P = 0.17). The mean rates of morcellation were 3.4 g/min and 4.3 g/min (P = 0.20). The HoLEP efficiency increased as a function of gland size (R(2) = 0.56). CONCLUSIONS: Holmium laser enucleation of the prostate is a reproducible technique, as there is little variation in efficiency from one surgeon to another. Furthermore, the efficiency of HoLEP increases as prostate size increases, which suggests that HoLEP may be an ideal treatment for men with large prostates.

Using and choosing a nephrostomy tube after percutaneous nephrolithotomy for large or complex stone disease: a treatment strategy.

BACKGROUND AND PURPOSE: Percutaneous nephrolithotomy (PCNL) is a well-accepted technique for removal of large or complex renal calculi. However, little attention has been paid to strategies for nephrostomy tube (NT) selection. We reviewed the reasons for selecting three types of NT after PCNL for large or complex stone disease. PATIENTS AND METHODS: A series of 106 consecutive renal units undergoing PCNL for stone burdens >2 cm by a single surgeon (JEL) were reviewed. Noncontrast CT (NCCT) was carried out on postoperative day 1, and secondary procedures were performed if fragments remained. The NTs studied were 8.5F and 10F Cope loops (CP), 20F reentry Malecot catheters (REM), and 20F circle loops (CL). Patient demographics, access site and number, complications, and stone type were examined. "Stone free" was defined as a negative NCCT or negative second-look PCNL. RESULTS: A total of 134 accesses were created in 106 renal units: 35 upper, 7 mid, and 92 lower; however, only 111 NTs were placed: 85 CP (76.6%), 19 REM (17.1%), and 7 CL (6.3%). Sixteen accesses were performed tubeless; all but two were in the upper pole. All 16 of these renal units had a concomitant NT placed in the lower pole. Multiple sites were accessed in 21 patients; 7 of these patients had CL placed. Five of ten patients with spinal-cord injury had REM/CL placed. Nineteen REM were placed: 10 for drainage of infection, and 9 for difficult anatomy. All renal units were rendered stone free: 31.1% with a single procedure and 95.6% with one or two procedures. There were no difficulties with drainage or access for secondary PCNL regardless of the NT employed. Complications included two hydrothoraces, one arteriovenous fistula, and one ureteral perforation. Three of four renal units in patients requiring transfusions underwent bilateral PCNL, and at least one renal unit required multiple accesses. Of kidneys with infection stones, 57.1% required REM or CL; only 12.0% of nonstruvite stones necessitated REM or CL. CONCLUSIONS: All patients having PCNL done for complex stone disease should have an NT placed; however, small (8.5F-10F) CP suffice in most cases and can provide greater patient comfort. To minimize pleural morbidity, tubeless upper-pole access should be considered if the kidney is judged to be stone free at the conclusion of PCNL. Circle loops are useful when multiple accesses are necessary, whereas REM are appropriate if access is difficult, gross residual stone remains, or pain is not an issue (i.e., spinal-cord injury).

High-powered holmium-laser ablation: comparison of setting effectiveness using tissue-surrogate model.

BACKGROUND AND PURPOSE: The 100-W holmium laser, in conjunction with a sidefiring 550-microm fiber, can ablate prostate glands as large as 40 g to relieve lower urinary-tract symptoms. We evaluated the effect of various setting combinations on ablation efficiency using beef kidney as a tissue-surrogate model. MATERIALS AND METHODS: Beef kidney specimens (mean weight 44.8 +/- 3.1 g) were secured in a cylinder, which was submerged in a water-filled tank through which a 27F resectoscope and 550-microm sidefiring fiber were positioned. Four energy/frequency combinations were tested, with each used to treat 10 kidney specimens. The difference between the mean pretreatment and post-treatment weights of each treatment group were compared statistically with Student's t-test. RESULTS: The largest mean weight difference after treatment (8.94 +/- 2.38 g) was achieved using 3.2 J and 25 Hz. This mass reduction was significantly greater than that of all other combinations except 2.5 J and 40 Hz. CONCLUSIONS: Use of the 3.2 J and 25 Hz setting combination resulted in the greatest amount of ablation in this tissue-surrogate model, suggesting that maximal energy settings may provide an advantage in tissue vaporization using the 100-W holmium laser. Clinical assessment must be performed to substantiate these findings.

Percutaneous nephrolithotomy for caliceal diverticular calculi: a novel single stage approach.

PURPOSE: Current percutaneous treatment of symptomatic caliceal diverticular calculi involves renal access, stone removal, dilation of the diverticular communication, fulguration of the cavity and placement of a nephrostomy tube. We reviewed the outcomes of patients undergoing a novel single stage percutaneous nephrolithotomy technique for radiopaque caliceal diverticular stones that eliminates ureteral catheterization and entry into the renal collecting system. MATERIALS AND METHODS: A total of 21 patients (8 male and 13 female including 1 bilateral) with a mean age of 42.4 years underwent percutaneous nephrolithotomy for caliceal diverticular stones from February 2001 to May 2003. Of the diverticula 12 were upper pole, 4 were interpolar and 6 were lower pole. Infracostal access was established by the urologist directly onto the radiopaque stones without the aid of a ureteral catheter. After balloon tract dilation a 30Fr Amplatz sheath was placed and following stone removal the diverticulum was fulgurated. The infundibulum was neither cannulated nor dilated. A 20Fr red rubber catheter or an 8.5Fr Cope loop was placed into the diverticulum. Stone-free status was assessed by noncontrast computerized tomography on postoperative day 1 (POD1). The drainage tube was removed if there was no urine drainage and the kidney was stone-free. Excretory urography was performed at 3 months to evaluate diverticular resolution. RESULTS: Of 21 patients 20 were discharged home tubeless on POD1 and 18 of 21 (85.7%) renal units were stone- free on POD1 noncontrast computerized tomography. Mean operative time was 58.5 minutes and mean stone burden was 138.9 mm. Mean stone diameter was 11.6 mm and mean diverticular diameter was 15.3 mm. Of 22 renal units 16 had followup excretory urography. All diverticula decreased in size and 14 (87.5%) had complete resolution. CONCLUSIONS: In patients with symptomatic radiopaque caliceal diverticular stones, a single stage procedure without the need for ureteral catheterization combined with direct infracostal diverticular puncture allows for a rapid procedure with little morbidity.

Shock wave lithotripsy of stones implanted in the proximal ureter of the pig.

PURPOSE: Ureteral stones can be difficult to treat with shock wave (SW) lithotripsy. A strategy for lithotripsy of proximal ureteral stones is to push them back into the renal pelvis prior to administering SWs. However, push-back is invasive and not always possible. Since there are few clues to suggest how best to treat ureteral stones with SWs in situ, we developed an animal model for research on lithotripsy for ureteral stones. MATERIALS AND METHODS: Gypsum model stones were implanted bilaterally in the proximal ureter and renal calix of the pig via percutaneous access. Lithotripsy was performed using a HM3 lithotripter (Dornier Medical Systems, Marietta, Georgia) and stones at each location were treated with the same dose (400 SWs, 20 kV and 30 SWs per minute). Fragments were collected and the percent increase in projected surface area of the particles was determined. RESULTS: The breakage (mean percent area increase) of stones implanted in the proximal ureter was significantly less than that of stones located in the renal calix treated with the same dose of shock waves (134% vs 327%, p <0.001). Also, stones that were fully confined by the ureter did not break as well as stones located at the ureteropelvic junction. This indicates that the physical environment surrounding a stone can have a significant effect on the efficiency of SW action. CONCLUSIONS: The observation that stones implanted in the ureter showed decreased breakage compared with stones in the kidney is consistent with clinical experience. This finding is a valuable and even essential prerequisite for any experimental animal model system intended for the study of SW action in the breakage of ureteral stones.

Stone formation is proportional to papillary surface coverage by Randall's plaque.

PURPOSE: Randall's plaques are common in calcium oxalate (CaOx) stone formers (SF). Plaque coverage correlates directly with urine calcium excretion and inversely with urine volume. We hypothesize that plaque coverage should increase proportionally with increasing stone number. We measured plaque areas in idiopathic CaOx stone formers and nonstone formers (NSF), and identified significant relationships with quantified stone histories. MATERIALS AND METHODS: A total of 13 SFs and 4 control NSFs underwent nephroscopic papillary mapping with representative still images and MPEG (Moving Pictures Experts Group) movies used to identify plaque and papillary borders. Stone histories were obtained through patient interviews, and from medical records and radiographs. The relationship of plaque coverage to clinical stone events was assessed by general multivariate linear modeling. Log transformation normalized the distribution of percent plaque coverage and stone number. RESULTS: Plaque surface area in SFs differed significantly from that in NSFs (p <0.0001). The duration of stone disease and the log transformed percent plaque coverage correlated significantly with the number of stones (0.677 and 0.620, p = 0.003 and 0.008, respectively). On multivariate analysis and correcting for the duration of stone disease total percent plaque coverage correlated significantly with the number of stones (R = 0.496, p = 0.05). Disease duration and plaque coverage did not correlate significantly (p = 0.257). CONCLUSIONS: Percent plaque coverage directly correlates with the number of stones formed even when corrected for the duration of stone disease. However, plaque coverage does not correlate with the duration of stone disease. These results support the hypothesis that the pathogenesis of CaOx stones begins with Randall's plaques.

Transperitoneal laparoscopic pyelolithotomy after failed percutaneous access in the pediatric patient.

PURPOSE: We present our experience with transperitoneal laparoscopic pyelolithotomy in pediatric patients in whom percutaneous renal access failed and the stone burden warranted open intervention. MATERIAL AND METHODS: A transperitoneal laparoscopic approach was used for pyelolithotomy in 8 patients 3 months to 10 years old (mean age 4 years). Percutaneous access failed secondary to a nondilated system and/or an occluding lower pole calculus. Inclusion criteria were failed percutaneous access secondary to a nondilated system and/or stone occlusion of the lower pole system and failed shock wave lithotripsy or a stone burden of greater than 2.5 cm2. A posterior pelviotomy was made. Stones in the renal pelvis were removed with rigid graspers under direct laparoscopic vision. A flexible cystoscope was introduced through a port if caliceal stones were present. The renal pelvis was reconstructed. A watertight anastomosis was verified. RESULTS: Average operative time was 1.6 hours (range 0.8 to 2.3). Mean hospital stay was 2.15 days (range 2 to 3). A range of 1 to 3 stones (median of 1) were removed and the mean stone burden was 2.9 cm2. No intraoperative complications were noted. Stone analysis revealed 3 patients with calcium oxalate stones, 1 with a calcium phosphate stone and 4 with cysteine stones. There was 1 patient with stone recurrence at a mean followup of 12 months (range 3 to 20). Thus, the overall long-term stone-free rate was 87.5%. CONCLUSIONS: Transperitoneal laparoscopic pyelolithotomy is feasible when percutaneous access fails and open pyelolithotomy is considered due to a large stone burden.

An update on ureteroscopic instrumentation for the treatment of urolithiasis.

PURPOSE OF REVIEW: Ureteroscopic instruments, both endoscopic and working devices, continue to evolve. Changes in instrumentation have necessitated concurrent modifications in ureteroscopic techniques over the years. The safety and efficacy of the ureteroscopic approach for the treatment of renal and ureteral calculi, however, have continued to improve. RECENT FINDINGS: This review emphasizes the recent advances in the major groups of instruments employed for ureteroscopy. Among the endoscopic instruments, the flexible ureteroscopes have undergone the most notable advances, benefiting from greatly improved deflection and durability. Progress has been made in adjunctive instruments as well. Current stone retrieval devices composed of nitinol-based wire technology are able to easily secure fragments from the most peripheral calices. The holmium laser is a versatile device with proven safety and effectiveness as an endoscopic lithotrite. SUMMARY: The availability and coordinated use of the latest ureteroscopic instruments have resulted in better treatment outcomes, thus expanding the use of ureteroscopy as a first-line option for the treatment of calculi in appropriate cases. Urologists should be familiar with currently available instrumentation in order to optimize their equipment.

In vitro assessment of lithoclast ultra intracorporeal lithotripter.

PURPOSE: The Lithoclast Ultra (Boston Scientific Corporation, Natick, MA) enables the simultaneous application of ultrasonic and pneumatic modalities for the fragmentation and removal of stones during percutaneous nephrolithotomy (PCNL). We evaluated the effectiveness of this unit using a hands-free in vitro testing system. MATERIALS AND METHODS: An in vitro test system was used to assess the efficiency of stone penetration when the Lithoclast Ultra was operated at different settings of ultrasonic power and pneumatic frequency. The pneumatic and ultrasonic handpieces were assembled, the probes were inserted into an irrigation sheath (Cook Urological, Spencer, IN), and the complete unit was mounted upright (probe tip up). A gypsum artificial stone (mean length 12.8 +/- 0.6 mm; mean diameter 7.6 +/- 0.1 mm) was centered on the probe tip. A weight (63.4 g) was placed atop the stone to provide a constant force. Pneumatic frequency settings of 12, 8, 4, and 1 Hz were tested in conjunction with ultrasonic power settings of 100%, 70%, and 40%. The times required for complete stone penetration were assessed for each combination of settings. Differences in mean stone penetration times were compared using ANOVA. RESULTS: The combination of 12 Hz and 100% produced the fastest mean stone penetration time (8.9 +/- 1.1 seconds). Stone penetration times decreased significantly with increases in pneumatic frequency (P< 0.001) as well as with increases in ultrasonic power (P= 0.001). When analyzing the effect of each modality on the total improvement in penetration time, increasing the pneumatic frequency accounted for approximately 80% of the performance improvement. The stone penetration times were better than those of the most efficient ultrasonic device previously evaluated using this test system. CONCLUSIONS: The Lithoclast Ultra exhibited excellent stone penetration efficiency when evaluated with a hands-free in vitro test system. Increases in either pneumatic frequency or ultrasonic power significantly improve penetration times, with the pneumatic modality contributing the majority of the effect.