Role of stone analysis in metabolic evaluation and medical treatment of nephrolithiasis.

BACKGROUND AND PURPOSE: Comprehensive metabolic evaluation has become an important aspect of the management of recurrent nephrolithiasis, yet the role of stone analysis is often neglected or perhaps underestimated. The purpose of this study was to determine the role of stone analysis in medical decision making in patients with recurrent nephrolithiasis. MATERIALS AND METHODS: We evaluated 100 consecutive stone-forming patients who had undergone compositional stone analysis as well as comprehensive metabolic evaluation at our institution. An analysis of stone composition in relation to metabolic disturbances was performed. Patients were stratified into two groups: calcium and non-calcium stone formers. RESULTS: Patients having non-calcium stones were found to have a metabolic analysis reflecting specific metabolic disorders. Alternatively, patients with calcium stones were heterogeneous with regard to metabolic disorders, but there was a significant likelihood of renal tubular acidosis in those patients with calcium phosphate calculi. On the basis of these results, a simplified metabolic evaluation and nonselective medical therapy based on stone composition was formulated to facilitate assessment, management, and monitoring of stone disease. CONCLUSIONS: Compositional stone analysis should be an integral part of the metabolic evaluation of patients with nephrolithiasis. Moreover, stone analysis alone may provide guidance for therapeutic treatment and obviate a formal metabolic evaluation.

Incorporation of patient preferences in the treatment of upper urinary tract calculi: a decision analytical view.

PURPOSE: Patient preferences, or utilities, may be crucial to select an appropriate treatment plan for stone disease. We used decision modeling to understand better patient choices and decision making in the overall management of recurrent nephrolithiasis. MATERIALS AND METHODS: We interviewed 180 consecutive patients with active stone disease. Demographic data and historical experiences with calculi were recorded. Patients were presented with 6 hypothetical clinical scenarios and various treatment options. The standard gamble method was used to obtain utility values for each option. RESULTS: Nephrectomy had the lowest mean utility value of 0.883. Percutaneous nephrolithotomy for severe, moderate and mild pain had utilities of 0.924, 0.932 and 0.947, respectively. Shock wave lithotripsy for the management of mild pain was the most attractive option (mean utility 0.968). The utility for long-term medical therapy was 0.949, which was between that of percutaneous nephrolithotomy and shock wave lithotripsy for mild pain. Patients with a surgical history of stone removal assigned lower utilities to invasive procedures (nephrectomy, percutaneous nephrolithotomy, p <0.05). As the incidence of spontaneous stone passage increased, a higher utility was given to long-term medical therapy (p <0.05). Patients on medical therapy less than 1 year did not appreciate a significant benefit of medical prophylaxis. However, longer compliance with medical management led patients to perceive increasing benefits of continuing such medical treatment (p <0.05). Patients who had undergone stone removal via endoscopic or open surgery also had a higher preference for medical therapy (p <0.05). CONCLUSIONS: Patients who had undergone stone removal wanted to avoid future invasive procedures. They ranked long-term medical therapy below shock wave lithotripsy but above invasive procedures, such as percutaneous nephrolithotomy. Most importantly, patients appreciated the benefits of medical therapy the longer that they complied with specific recommendations. These results support the concept that patients perceive long-term medical therapy to prevent recurrent nephrolithiasis as a desirable treatment option.

Advances in digital imaging during endoscopic surgery.

BACKGROUND AND OBJECTIVE: Digital imaging capabilities have recently been incorporated into a number of video systems. Contrast enhancement when using a rigid or semirigid endoscope improves image definition by seeking out existing transitions in detail. Only the areas of transition are accentuated, whereas areas without detail are unaffected. During flexible endoscopy, fiberoptic bundles create a classic honeycomb appearance. The use of "fiberscope" filters minimizes this appearance by expanding the image of each fiberoptic fiber. We therefore assessed whether new developments in digital video image processing have improved image quality for endoscopic surgery. MATERIALS AND METHODS: Fifty urologists reviewed a video playback of various endourologic procedures. The type of endoscope was identified, but the urologic surgeon was blinded to the level of enhancement (high or low) or fiberscope filter (A or B) used. Each video clip was scored from 1 to 5 for the following image variables: identification of structure, detail of image, and background noise or interference. All results were averaged and compared using Student's paired t-test. RESULTS: During rigid endoscopy, the high and low digital enhancement settings were both superior to no enhancement (P < 0.001), and high enhancement was better than low (P < 0.001). With semirigid endoscopic procedures, high and low digital enhancement were comparable but were superior to no enhancement (P < 0.001). Filters A and B were no better than no enhancement. There was a significant improvement noted with the use of filter A or B during flexible ureteroscopy over no enhancement (P < 0.001). In addition, filter A was better than filter B (P < 0.001). CONCLUSIONS: Digital enhancement settings during video endoscopy significantly improve images from rigid and semirigid endoscopes. The digital fiberscope filter significantly improves images obtained during flexible ureteroscopy. Digital image enhancement capabilities should be strongly considered when upgrading video systems. Digital technology must be further studied to improve clinical video imaging during endoscopic surgery.

Secure transmission of urologic images and records over the Internet.

PURPOSE: Telemedicine has become a common method for the transmission of images and patient data across long distances. Our goal was to assess the efficiency and accuracy of Photomailer MD software, a store-and-forward telemedicine system, in the urologic setting. METHODS: Photomailer MD software was loaded on two computers in the host institution, one with a T1 connection to the Internet and the other with a dial-up modem connection (24,000 bits/second), and computers at three remote sites. A total of 14 clinical cases, comprised of digitized histories and radiographic images, were sent to the remote institutions four separate times using the four transmission modes available: nonencrypted, 56-bit encryption, 128-bit encryption, and 128-bit encryption with password. The following data points were recorded: file size before and after encryption, file transmission times, and diagnostic accuracy of the remote urologists. One-way ANOVA was used to compare mean values statistically, while the z-test was used to compare diagnostic accuracies. RESULTS: Encryption increased the file size by a mean of 37.8%, with the three encryption modes increasing file sizes by the same number of kilobytes. When a dial-up modem was used, encrypted files required a significantly longer transmission time (P < 0.05) than the unencrypted files. The same trend was seen with the T1 connection, although the differences often were not significant. When T1 transmission times were compared with modem times with other variables held constant, modem times were significantly longer (P < 0.05). Diagnostic accuracies for each of the three remote centers ranged from 85.7% to 100%. Differences in accuracy rates between attending physicians and residents were not significant. CONCLUSIONS: Photomailer MD provides a secure, convenient, and affordable method of transmitting patient images and records via the Internet. Transmission speed was significantly greater when using a T1 line and also tended to be faster when files were not encrypted. There was no significant difference in transmission time among the three encryption modes; therefore, 128-bit encryption with a password should be used to maximize security. Diagnostic accuracies were comparable to those in the literature. In general, 640 x 480-pixel resolution was adequate for urologic diagnoses, although higher-resolution images may improve accuracy.

Incidence and management of gynaecological-related ureteric injuries.

We report a 5-year review of all ureteric injuries at a major Sydney teaching hospital as a result of gynecological procedures. A retrospective analysis was made of all hospital medical records and consultant follow-up notes from January,1990 to May, 1995. Injuries were recorded in 22 patients with a mean age 52 years (range 31-88). Of these, 17 occurred at our institution, while 5 were referred from peripheral hospitals. Two injuries were bilateral, and 6 were discovered intraoperatively. Patients were managed acutely where possible. Treatment options included cystoscopy and retrograde stenting, deligation, neoureterocystostomy, transureteroureterostomy or nephrectomy. Follow-up imaging was available in 16 patients, of those, 15 were normal, and 1 showed bilateral obstruction secondary to radiotherapy. The overall risk of ureteric injury for all methods of hysterectomy was 0.44% (0.24% for total abdominal hysterectomy).

Use of ureteroscopy and holmium:YAG laser in patients with bleeding diatheses.

OBJECTIVES: To assess the safety and efficacy of ureteroscopy and holmium laser in patients with known bleeding diatheses and upper tract calculi or transitional cell carcinoma (TCC). METHODS: Eight patients with stone disease and 1 patient with upper tract TCC were treated ureteroscopically with the holmium laser. The mean age was 58.3 years (range 42 to 74). Six patients were receiving Coumadin, with a mean international normalized ratio (INR) of 2.1 (normal INR less than 1.1). Two patients were thrombocytopenic, and 1 had von Willebrand's disease. None of the bleeding diatheses were corrected before surgery. Semirigid or flexible ureteroscopes were used to access the ureter or intrarenal collecting system. The holmium laser was used to fragment calculi or ablate tumor. RESULTS: Only 1 patient had a postoperative bleeding complication related to the procedure, involving an episode of oliguria secondary to a small ureteral clot. This cleared without surgical intervention. Another patient developed an episode of epistaxis after administration of ketorolac for pain. Six of 7 patients who underwent laser fragmentation for calculi were stone free on follow-up intravenous urogram at 1 month, and no tumor recurrence was noted in the patient with TCC (follow-up of 4 months). CONCLUSIONS: Ureteroscopy allowed excellent access to all regions of the upper tracts, and holmium laser fragmentation of calculi or ablation of tumor was effective in managing each particular problem. Use of the holmium laser with ureteroscopic access provides a safe and acceptable combination for treating upper tract pathology in patients with uncorrected bleeding diatheses. As a result, these patients can avoid added costs of extended hospital stay and risks associated with transfusions.

Transvaginal repair of vesicovaginal fistulas after hysterectomy by vaginal cuff excision.

PURPOSE: When repairing vesicovaginal fistulas after hysterectomy there is often reluctance to excise totally the fistula tract for fear of enlarging the tissue defect. It has been suggested that consequent tension on suture lines may cause recurrence of an even larger fistula. On the other hand, a basic surgical principle is that scar tissue margins will not heal as quickly or at all compared to fresh viable margins. We reviewed whether our technique of total excision of the fistula tract and vaginal cuff scar provides an efficient cure rate. MATERIALS AND METHODS: We retrospectively analyzed the outcomes of 20 women who underwent vaginal cuff excision repairs of a vesicovaginal fistula after total hysterectomy. Women who had complex fistulas and/or prior radiation therapy were excluded from study. RESULTS: Of the 20 patients 3 (15%) sustained a bladder lesion that was repaired intraoperatively and 7 (35%) underwent 1 or more attempts at secondary repair. All fistulas were at the vaginal cuff. Mean fistula size was 0.7 cm. (11 women). All repairs were performed as soon as possible after presentation except 2 (10%) that were delayed because of the fistula appearance. The fistula tract was excised totally in all patients. All patients were cured. There were no postoperative complications and no significant or symptomatic vaginal shortening. CONCLUSIONS: Transvaginal vaginal cuff excision repair is an effective first attempt cure of vesicovaginal fistulas after hysterectomy. Excision of the fistula tract and vaginal cuff scar enables the surgeon to suture viable tissues in every layer, thereby providing conditions optimal for wound healing. This procedure obviates the need to wait for tissue readiness and to interpose a flap in the majority of patients.

Retrograde balloon cautery incision of ureteropelvic junction obstruction.

Retrograde balloon endopyelotomy has produced durable success rates of approximately 80% for all patients with UPJ obstruction. Patients with poor renal function, high-grade hydronephrosis, or stricture lengths of more than 2 cm fair worse, and these factors should be considered prior to balloon endopyelotomy. The debate concerning the functional significance of crossing vessels continues. However they are probably more important in terms of the risk of postoperative bleeding than in regards to overall success rates. With the use of endoluminal ultrasound, angiography, or spiral CT, patients with significant size crossing vessels can be identified preoperatively. The retrograde approach to UPJ obstruction using a cutting balloon is a quick and relatively inexpensive (shorter operative time and hospital stay, and no percutaneous nephrostomy) method for accomplishing an endopyelotomy incision. With the development of the 5-F balloon catheter and the use of a 7-F post-endopyelotomy stent, the need to stent the ureter for 7 days prior to the procedure is overcome. In this regard, the entire retrograde endopyelotomy may be performed in a one-step outpatient procedure.

Impact of holmium laser settings and fiber diameter on stone fragmentation and endoscope deflection.

We compared the impact of various energy settings, frequency, and fiber diameters on the stone fragmentation capabilities of the holmium laser. Stone phantoms, made from plaster of Paris and uniform in weight, were treated with one of two laser fiber sizes: small (200 and 365 microm) and large (550 and 1000 microm). Stones were immersed in water and fragmented for 3 minutes at 0.5, 1.0, or 2.0 J and 5, 10, or 15 Hz. The mean percentage decrease in weight in the two groups was compared using one-way ANOVA. The effect on flexible ureterorenoscope deflection of the small fibers was tested in two different ureterorenoscopes. Raising the energy level when using the small fibers resulted in more weight loss (P < 0.05). Increasing the frequency up to 10 Hz also resulted in a significant increase in weight loss (P < 0.05), yet above 10 Hz, there was no significant additional weight loss noted for either small fiber. There was no significant difference in the weight loss produced by the two fibers unless the energy setting was >1.0 J. Studies with the large fibers demonstrated similar results, with significant increments of weight loss occurring with increased energy (P < 0.05), while nonsignificant differences were seen for the two fiber diameters. Increasing laser frequency up to 15 Hz resulted in a significant increase in weight loss for the large fibers. Loss of ureterorenoscope deflection ranged from 7% to 16% and 18% to 37% for the 200-microm and 365-microm fibers, respectively. Small-diameter fibers, in combination with semirigid or flexible ureteroscopes, should be used to treat upper urinary tract stones. The 365-microm fiber should be utilized for the management of ureteral stones, as minimal endoscopic deflection is required to access these calculi. Because the 200-microm fibers are considerably more expensive, their use should be reserved for fragmentation of intrarenal calculi, where maximum deflection is required during flexible ureterorenoscopy. The ideal energy and frequency settings for the small fibers are <1.0 J and 5 to 10 Hz. Larger fibers can be used for managing bladder or renal calculi, as there is no need for significant fiber deflection. The 550-microm fiber is preferred, as it is comparable in efficacy to the 1000-microm fiber and is less expensive. Energy and frequency can be maximized to 2.0 J and 15 Hz without damage to the fiber, but visibility can be affected by high frequencies. Appropriate fiber selection and energy/frequency settings will allow access to most stones throughout the urinary tract, maximize fiber life, and minimize fiber expense.

Secured medical imaging over the Internet.

The Internet has established itself as an affordable, extremely viable and ubiquitous communications network that can be easily accessed from virtually any point in the world. This makes it ideally suited for medical image communications. Issues regarding security and confidentiality of information on the Internet, however, need to be addressed for both occasional, individual users and consistent enterprise-wide users. In addition, the limited bandwidth of most Internet connections must be factored into the development of a realistic usermodel and resulting protocol. Open architecture issues must also be considered so that images can be communicated to recipients who do not have similar programs. Further, application-specific software is required to integrate image acquisition, encryption and transmission into a single, streamlined process. Using Photomailer software provided by PhysiTel Inc., the authors investigated the use of sending secured still images over the Internet. The scope of their investigation covered the use of the Internet for communicating images for consultation, referral, mentoring and education. Photomailer software was used at several local and remote sites. The program was used for both sending and receiving images. It was also used for sending images to recipients who did not have Photomailer, but instead relied on conventional email programs. The results of the investigation demonstrated that using products such as Photomailer, images could be quickly and easily communicated from one location to another via the Internet. In addition, the investigators were able to retrieve images off of their existing email accounts, thereby providing greater flexibility and convenience than other systems which require scheduled transmission of information on dedicated systems. We conclude that Photomailer and similar products may provide a significant benefit and improve communications among colleagues, providing an inexpensive means of sending secured images on the Internet.