James D. Watterson

HOLMIUM: YAG LASER LITHOTRIPSY FOR UPPER URINARY TRACT CALCULI IN 598 PATIENTS

PURPOSE We assessed the effectiveness and safety of holmium:YAG laser lithotripsy for managing upper urinary tract calculi in a prospective cohort of 598 patients. MATERIALS AND METHODS Ureteroscopic holmium:YAG laser lithotripsy was performed in 598 patients between 1993 and 1999. Calculi were located in the distal ureter in 39.6% of cases, mid ureter in 18.6%, proximal ureter in 32.4% and kidney in 9.4%. Patients were treated on an outpatient basis with various flexible and semirigid endoscopes. Of the cases 59% were referred as previous treatment failures. Patients were assessed 6 to 12 weeks postoperatively with repeat plain x-ray and ultrasound or excretory urography for late obstructive complications. RESULTS The overall stone-free rate was 97%. As stratified by location, the stone-free rate was 98% in the distal ureter, 100% in the mid ureter, 97% in the proximal ureter and 84% in the kidney. Fragmentation was incomplete in 6% of cases and secondary intervention was required in 6%. The overall complication rate was 4%. New onset ureteral stricture developed postoperatively in 0.35% of patients. CONCLUSIONS Holmium:YAG laser lithotripsy is a highly effective and safe treatment modality for managing ureteral and a proportion of intrarenal calculi on an outpatient basis. The effectiveness and versatility of the holmium laser combined with small rigid or flexible endoscopes make it our modality of choice for ureteroscopic lithotripsy.

Safety and efficacy of holmium:YAG laser lithotripsy in patients with bleeding diatheses

Purpose: To assess the safety and efficacy of ureteroscopy and holmium:YAG (yttrium-aluminum-garnet) laser lithotripsy in the treatment of upper urinary tract calculi in patients with known and uncorrected bleeding diatheses. Materials and Methods: A retrospective chart review from 2 tertiary stone centers was performed to identify patients with known bleeding diatheses who were treated with holmium:YAG laser lithotripsy for upper urinary tract calculi. Twenty-five patients with 29 upper urinary tract calculi were treated with ureteroscopic holmium laser lithotripsy. Bleeding diatheses identified were coumadin administration for various conditions (17), liver dysfunction (3), thrombocytopenia (4), and von Willebrands disease (1). Mean international normalized ratio (INR), platelet count and bleeding time were 2.3, 50 x 109/L, and > 16 minutes, for patients receiving coumadin or with liver dysfunction, thrombocytopenia, or von Willebrands disease, respectively. Results: Overall, the stone-free rate was 96% (27/28) and 29 of 30 procedures were completed successfully without significant complication. One patient who was treated concomitantly with electrohydraulic lithotripsy (EHL) had a significant retroperitoneal hemorrhage that required blood transfusion. Conclusions: Treatment of upper tract urinary calculi in patients with uncorrected bleeding diatheses can be safely performed using contemporary small caliber ureteroscopes and holmium laser as the sole modality of lithotripsy. Ureteroscopic holmium laser lithotripsy without preoperative correction of hemostatic parameters limits the risk of thromboembolic complications and costs associated with an extended hospital stay. Avoidance of the use of EHL is crucial in reducing bleeding complications in this cohort of patients.

A Randomized Prospective Blinded Study Validating Acquistion of Ureteroscopy Skills Using A Computer Based Virtual Reality Endourological Simulator

PURPOSE Surgical simulation has emerged in the last decade as a potential tool for aiding acquisition of technical skills, including anesthesia protocols, trauma management, cardiac catheterization and laparoscopy. We evaluate and validate the use of a computer based ureteroscopy simulator (URO Mentor, Simbionix Ltd., Lod, Israel) in the acquisition of basic ureteroscopic skills. MATERIALS AND METHODS We assessed 20 novice trainees for the ability to perform basic ureteroscopic tasks on a computer based ureteroscopy simulator. Participants were randomized to receive individualized mentored instruction or no additional training, and subsequently underwent post-testing. Pre-training and post-training improvement in performance was assessed by objective simulator based measurements. Subjective overall performance was rated using a validated endourological global rating scale by an observer blinded to subject training status. RESULTS Demographics and pre-test scores were similar between groups. Post-testing revealed a significant effect of training on objective and subjective measurements. Spearman rank correlation demonstrated a significant association between objective simulator based measurements and the endourological global rating scale. CONCLUSIONS Use of a computer based ureteroscopy simulator resulted in rapid acquisition of ureteroscopic skills in trainees with no prior surgical training. Results of this study demonstrate the use of a virtual reality ureteroscopy simulator in endourological training. Correlation of simulator based measurements with a previously validated endourological global rating scale provides initial validation of the ureteroscopy simulator for the assessment of ureteroscopic skills.

Ureteroscopy and holmium:YAG laser lithotripsy: an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy

Abstract Objectives. To review the results of holmium laser lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy. Holmium:yttrium-aluminum-garnet (YAG) laser lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. Methods. A retrospective analysis was conducted at two tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium laser lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and two encrusted ureteral stents were treated. The mean gestational age at presentation was 22 weeks. The mean stone size was 8.1 mm. The stones were located in the proximal ureter/ureteropelvic junction (n = 3), midureter (n = 1), and distal ureter (n = 6). Results. Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetric or urologic complications were encountered. Conclusions. Ureteroscopy and holmium laser lithotripsy can be performed safely in all stages of pregnancy, providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

Safety and Efficacy of Holmium: Yag Laser Lithotripsy in Patients With Bleeding Diatheses

Purpose: We assessed the safety and efficacy of ureteroscopy and holmium:YAG laser lithotripsy for treating upper urinary tract calculi in patients with known and uncorrected bleeding diathesis.Materials and Methods: We retrospectively reviewed the charts at 2 tertiary stone centers to identify patients with known bleeding diathesis who were treated with holmium:YAG laser lithotripsy for upper urinary tract calculi. A total of 25 patients (29 upper urinary tract calculi) underwent ureteroscopic holmium laser lithotripsy. Bleeding diathesis involved warfarin administration for various conditions in 17 patients, liver dysfunction in 3, thrombocytopenia in 4 and von Willebrand’s disease in 1. The mean international normalized ratio, platelet count and bleeding time were 2.3, 50 × 109/l. and greater than 16 minutes in patients on warfarin and in those with liver dysfunction, thrombocytopenia and von Willebrand’s disease, respectively.Results: Overall the stone-free rate was 96% (27 of 28 cases) and 29 of 30 p...

Holmium: Yag Laser Endoureterotomy For Ureterointestinal Strictures

PURPOSE The management of ureterointestinal stricture in patients who have undergone urinary diversion can be challenging. Endourological techniques have been increasingly used in recent years for ureteral stricture. While long-term results may not be as reliable or durable as those of traditional open reconstructive surgical techniques, associated morbidity is much less. The holmium (Ho):YAG laser, which has cutting and coagulating properties, has been demonstrated to have many applications in urology. We report our experience with and long-term results of Ho:YAG laser endoureterotomy for ureterointestinal strictures. MATERIALS AND METHODS We reviewed the charts and followup history of 23 patients in whom the Ho:YAG laser was used to treat ureterointestinal anastomotic stricture. Strictures were treated percutaneously via the antegrade approach with flexible endoscopes and the holmium laser. A reversed 12/6Fr endopyelotomy stent was left indwelling for 6 weeks postoperatively. Success was defined as symptomatic improvement and radiographic resolution of obstruction. RESULTS Between 1993 and 2000, 23 patients with a mean age of 61 years underwent endo-ureterotomy using the Ho:YAG laser for 24 ureterointestinal stricture. An overall success rate of 71% (17 of 24 cases) was achieved at a mean followup of 22 months. The success rate of holmium laser endoureterotomy for ureterointestinal stricture at 1, 2 and 3 years was 85%, 72% and 56%, respectively. Seven patients had recurrent strictures of which 4 developed 16 months or more postoperatively. No complications were noted. CONCLUSIONS Ho:YAG laser endoureterotomy for ureterointestinal stricture disease is a minimally invasive endourological procedure that may provide more durable results than other modalities used for endoureterotomy. The Ho:YAG laser with its ability to cut tissue precisely and provide hemostasis combined with its versatility and compatibility with flexible endoscopes is an ideal instrument for safely performing endoureterotomy.

Oxalate-Degrading Enzymes from Oxalobacter formigenes: A Novel Device Coating to Reduce Urinary Tract Biomaterial-Related Encrustation

BACKGROUND AND PURPOSE The long-term placement of biomaterials within the urinary tract is limited by the development of encrustation. In a noninfected urinary environment, encrustation often results from the deposition of calcium oxalate on the biomaterial surface. There is an association between the absence of Oxalobacter formigenes, a commensal colonic bacterium capable of degrading oxalate, and calcium oxalate stone formation. This pilot study was designed to evaluate several oxalate-degrading enzymes produced by O. formigenes as a potential biomaterial coating to reduce urinary tract encrustation. MATERIALS AND METHODS Circular silicone disks of 6-mm diameter were incubated for 48 hours in oxalylcoenzyme A decarboxylase (OXC), formyl-coenzyme A transferase (FRC), and coenzyme A, while control disks were incubated in distilled water. The adsorption of OXC and FRC was assessed using enhanced chemiluminescence (ECL) and atomic force microscopy (AFM). Coated and uncoated disks (20 of each) were implanted in the bladders of 40 female New Zealand White rabbits. After 30 days, the disks were recovered, and the degree of encrustation on the polymer surface was evaluated utilizing dry weight measurement, calcium atomic absorption spectroscopy (AAS), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX). RESULTS Both ECL and AFM demonstrated coating of the silicone disks with OXC and FRC. The mean dry weights of the coated and control disks following explantation were 0.591 +/- 0.438 g and 0.747 +/- 0.428 g, respectively (P = 0.307). The mean weight of calcium on the coated and control disks, as determined by AAS, was 154.1 +/- 96.25 mg and 258 +/- 181.35 mg, respectively (P = 0.008). CONCLUSIONS The use of oxalate-degrading enzymes from O. formigenes to coat urinary biomaterials represents a novel paradigm to reduce biomaterial-related encrustation. Coating of silicone with oxalate-degrading enzymes from O. formigenes results in a modest reduction in encrustation with no apparent toxicity. Further studies are warranted.

PERCUTANEOUS NEPHROLITHOTOMY OF A PELVIC KIDNEY: A POSTERIOR APPROACH THROUGH THE GREATER SCIATIC FORAMEN

Urolithiasis in a pelvic kidney can pose a management challenge to the urologist. We report on a patient with a symptomatic stone in a pelvic kidney managed by percutaneous nephrolithotomy through a posterior approach via the greater sciatic foramen. CASE REPORT

Swarming of Proteus mirabilis over ureteral stents: A comparative assessment

BACKGROUND AND PURPOSE Encrustation on indwelling ureteral stents is commonly related to the presence of urease-producing bacteria that elevate the pH of the urine through the hydrolysis of urea, resulting in the precipitation of calcium and magnesium salts. Using a model previously shown to measure accurately the ability of Proteus mirabilis to swarm over catheter surfaces (Eur J Clin Microbiol Infect Dis 1999;18:206), we investigated the ability of this organism to swarm over three ureteral stents with potential encrustation-resistance properties. MATERIALS AND METHODS Three commercially available ureteral stents were selected for evaluation: a low surface-energy stent, a hydrogel-coated stent, and a silicone stent. Ten-microliter aliquots of a 4-hour culture of P. mirabilis 296 in Trypticase soya (TSA) broth was inoculated 5 mm from a 1-cm channel cut out from TSA plates. Ten-millimeter stent sections were placed as bridges across the central channel adjacent to the inocula. Time to pathogen crossing was measured. RESULTS The mean time (+/- SD) to pathogen migration across the three test materials was 15.9 +/- 6.1, 19.8 +/- 9.5, and 29.7 +/- 14.3 hours for the low surface-energy, hydrogel-coated, and silicone stents, respectively. Statistical analysis revealed significant differences between the crossing times of the low surface-energy (P = 0.001) and hydrogel-coated (P = 0.034) stents compared with silicone but not between the low surface-energy and hydrogel-coated stents (P = 0.387). CONCLUSION Migration of P. mirabilis 296 across silicone stents was significantly reduced compared with low surface-energy and hydrogel-coated stents. These findings suggest that P. mirabilis may have a lower affinity for silicone stents, which may translate into a reduced risk of infection with P. mirabilis and associated stent encrustation.

Images: Port site recurrence on followup imaging after adrenalectomy for adrenocortical carcinoma — first indicator of carcinomatosis

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy of the adrenal cortex. Complete surgical resection is essential for localized tumours because ACC is highly resistant to chemotherapy and radiotherapy. 1 Use of a laparoscopic approach for adrenalectomy in the setting of a confirmed or suspected ACC is controversial because it is unknown if laparoscopy provides equivalent oncological outcomes compared to an open approach.