Nonvisualization of intravenous methylene blue in patients with clinically normal renal function

Urologists use intravenous dyes in diagnosing genitourinary fistulas and in investigating ureteral patency. Methylene blue and indigo carmine are the most common dyes used today. Generally, patients with clinically normal renal function demonstrate dye in their urine after several minutes. We report on 2 patients in whom methylene blue was not visualized after intravenous injection. A review of urologic and pharmacologic published reports led to a possible explanation for this phenomenon. Methylene blue can metabolize into leukomethylene blue, which is colorless in urine. Indigo carmine, however, is not readily metabolized but is rather freely filterable by the kidneys. Therefore, it is important to appreciate that nonvisualization of methylene blue may be a metabolism effect and not an anatomic one.

Requirements for urology and renal dialysis PC-based telemedicine applications: comparative analysis

The Imaging Science and Information Systems (ISIS) Center of the Department of Radiology at Georgetown University Medical Center (GUMC) has been developing technical requirements for different telemedicine applications. This paper details the process through which those technical requirements are determined and shows how they may differ substantially, depending on the clinical need. This information is presented in light of two telemedicine applications being undertaken at GUMC: a urology application for the management of patients with surgical stone disease and a nephrology application for monitoring of renal dialysis patients.

A telemedicine consultative service for the evaluation of patients with urolithiasis

OBJECTIVES

A 6-month pilot teleconsultative project linking Georgetown University Medical Center (GUMC) in Washington, DC, and City Hospital in Martinsburg, West Virginia, 90 miles away, was designed to assess the effectiveness of telemedicine on the clinical decision-making process for patients with urolithiasis.

METHODS

The telemedicine system designed and tested for this project was based on a PC-based platform. Videoconferencing and review of the patient's imaging studies were performed over an Integrated Service Digital Network (ISDN) with 3 Basic Rate (BRI) ISDN lines providing a 336-kilobytes/s bandwidth through an Inverse Multiplexor (IMUX). Treatment options were recorded for the clinical trial group and a simulated study group by the consulting urologist after the initial telephone consultation, after the telemedicine consultation, and after examination of those patients transferred to GUMC.

RESULTS

A total of 32 telemedicine consultations were performed: 14 in the clinical trial group and 18 in the simulated study group. The recommendation of the consulting urologist at the tertiary center was altered in 12 patients (37.5%) after the telemedicine consultation compared with the recommended treatment after the initial telephone consultation.

CONCLUSIONS

In the evaluation of patients with urolithiasis, this telemedicine application enhanced the clinical decision-making process by allowing for improved quality of care through immediate access and effective transfer of information between the referring urologist, the patient, and the stone center specialist.

A modification of standard percutaneous nephrolithotripsy technique for the morbidly obese patient

OBJECTIVES

Urolithiasis in the morbidly obese patient presents several unique challenges to the urologist, and its treatment often requires creativity and innovation. We present a new modification of standard percutaneous nephrolithotripsy (PNL) technique, which is very helpful in overcoming some of the problems that are encountered when performing PNL in this group of patients.

METHODS

We present 5 patients in whom this new technique has been used. Each had either failed prior extracorporeal shock-wave lithotripsy (ESWL) therapy or their size and abdominal girth precluded use of ESWL technology. All 5 patients underwent PNL. The radiographically measured skin-to-stone distances (determined by computed tomography or ultrasonography or both) exceeded the lengths of the standard percutaneous access sheaths and the 26 F rigid nephroscope. Thus larger and longer Amplatz access sheaths and a 30 F gynecologic laparoscope were used to reach the stones. Standard ultrasonic lithotripsy was then performed, and extralong bronchoscopic grasping forceps were used to remove stone fragments.

RESULTS

All 5 patients were rendered stone-free using this technique. There was no significant perioperative morbidity.

CONCLUSIONS

For this very challenging group of patients, the use of larger and longer access sheaths and the gynecologic laparoscope have been very effective additions to the urologists' armamentarium in the treatment of urolithiasis.

Technical tip: use of open-ended guidewire to facilitate laser lithotripsy during flexible ureteroscopy

You have just passed your flexible ureteroscope to the level of the upper-ureteral calculus. The stone is in view, but as you advance the laser fiber, it fails to exit the ureteroscope. All measures to advance the fiber prove futile. Sound familiar? We have found this to be an all too common and frustrating situation with the use of the flexible ureteroscope during laser lithotripsy. Our review of the literature reveals that this subject has not been adequately addressed. We have been successful with the aid of an open-ended 0.035-inch guidewire that admits the 320-microns laser fiber.

The effects of a soft tissue mimicking medium and increased power settings on the location and magnitude of lithotripter peak positive pressure

In vitro experiments showed that a tissue mimicking medium alters the peak positive pressure (p+), focal zone properties and frequency content of shockwaves compared with their behavior in water. The reduction in (p+) ranged from 5% at 10 kV. to 19% at 18.1 kV., when measured at the geometric focus with the tissue mimicking medium present. As power settings were increased, the relative gain in pressure was damped by attenuation. A 2 mm. shift in the acoustic focus was seen both axially and laterally with the tissue mimicking medium. While the former is probably not significant, the latter may be clinically significant given the narrow lateral beam width at the acoustic focus. These attenuation experiments suggest that clinical targeting through tissue may not be as precise or result in as high peak pressures as the clinician expects. Especially at high power settings, the depth of tissue traversed should be minimized to limit attenuation effects.

Primary hyperparathyroidism in patients with renal stones

There has been an observed decline in the incidence of renal stones in patients with primary hyperparathyroidism. Some believe that this is related to earlier surgical intervention. Two studies from the 1950s examined the reverse questions to determine the prevalence of primary hyperparathyroidism in patients with renal stones. This report examined 1,500 consecutive patients treated by lithotripsy seen at the Georgetown University Medical Center and found, using the historical criterion for diagnosis of hyperparathyroidism (a serum calcium level of 10.5 milligrams per deciliter or greater) that the prevalence had decreased significantly from 8.0 per cent to our level of 3.02 per cent. Neither age nor sex contributed significantly to this decrease, and there were significantly more calcium stones than in the previous studies. Using an elevated calcium level with an elevated chloride to phosphate ratio as criteria for a diagnosis of probable primary hyperparathyroidism, a true prevalence of 1.65 per cent (+/- 0.6 per cent) was found. We believe that there has been a significant decrease in the frequency of primary hyperparathyroidism in the general population of patients with renal stones.

Rhabdomyolysis: need for high index of suspicion

Rhabdomyolysis, both traumatic and nontraumatic, may be defined as a triad of skeletal muscle injury, pigmented urine, and acute renal failure. Nontraumatic rhabdomyolysis may be more of a subtle diagnosis and requires a high index of suspicion. Pertinent findings in the history as well as clinical evidence of muscle injury with a marked elevation of creatinine kinase will suggest the diagnosis. A disproportionate elevation of serum creatinine to blood urea nitrogen may also occur. Treatment consists of adequate hydration to help prevent oliguric or anuric renal failure without additional calcium or bicarbonate supplementation in most cases. Radiologic studies involving intravenous contrast media as well as urologic instrumentation should be avoided in the acute setting. With early diagnosis and prompt treatment the prognosis for recovery is excellent.

Ureteral stricture: experience with 31 cases

We reviewed the records of 31 patients treated during the last 5 years for ureteral stricture disease. The causes of stricture formation included ureteroenteral anastomoses (23 per cent), open ureterolithotomy (19 per cent), ureteroscopy (19 per cent), other urological procedures (16 per cent), general surgical and gynecological procedures (13 per cent) and miscellaneous causes (7 per cent). Of the patients 24 were managed initially with antegrade or retrograde balloon dilation or stenting and favorable outcomes were achieved in 12 (50 per cent), with a mean followup of 13 months. Of the 12 patients who failed endourological management 6 subsequently underwent open repair with a 100 per cent success rate. The remaining 7 patients underwent an open operation as the initial management and successful results were achieved in 6. The over-all rate of successful management of ureteral stricture disease using endoscopic and open surgical techniques was 77 per cent. A total of 7 patients (23 per cent) failed attempts at intervention: 5 showed evidence of decreasing renal function and 2 required nephrectomy.

New approaches in the treatment of renal calculi

Indications for intervention in patients with renal stone disease include persistent pain or bleeding, obstruction, infection and the presence of stones that are too large to pass spontaneously. Extracorporeal shock wave lithotripsy has revolutionized the surgical treatment of kidney stones. Contraindications include anticoagulation, bleeding diathesis, sepsis and renal malignancy. Stones in the renal pelvis and upper ureter are treated with shock wave lithotripsy; those in the lower ureter are best approached with the ureteroscope.

Management of the patient with cystinuria

Cystinuria is a complex hereditary disorder characterized by excessive urinary excretion of cystine. For the homozygote patient who excretes more than 400 mg per day, recurrent urinary calculus formation can necessitate repeat surgical manipulation with its associated morbidity. This review details the long-term medical management program for the patient with cystinuria and recurrent calculus formation.

Intraoperative localization of renal calculi

With the success of extracorporeal shock-wave lithotripsy and the percutaneous techniques of stone removal, conventional stone surgery will be reserved for the more complex cases. In order to reduce the recurrence rate, it is essential that all free calculi be removed at the time of surgery. The authors would suggest careful preoperative evaluation of stones with intravenous urography, tomography, and appropriate oblique and lateral views to determine size, number, and location of all calculi. Retrograde studies with a combination of contrast and CO2 can further define caliceal arrangement and identify obstructed calices or narrowed infundibuli that may require surgical repair. At the time of surgery, complete renal mobilization will facilitate all localization techniques. Elevation of the kidney with cotton tapes allows proper alignment of the x-ray beam and target (kidney and film). If extensive scar tissue or perinephric inflammation prevents adequate mobilization, the more maneuverable dental x-ray unit or ultrasonography will assist in localization of stones. A preliminary film will often provide considerably greater detail than even preoperative tomography. The surgeon needs to select the appropriate film type and exposure technique. Small stones (less than 2 mm) or poorly opacified stones may require use of a film that incorporates an intensification screen for improved resolution and contrast. Multiple small caliceal stones are best managed with careful needle localization prior to pyelotomy or nephrotomy. Anteroposterior and 90-degree views can give effective three-dimensional localization. If there remains any question or if localization is difficult because stones are poorly opaque or nonopaque, ultrasonography is useful to localize peripherally situated stones quickly and is best initiated prior to introducing air into the collecting system. To facilitate the speed of additional intraoperative films, especially once the vessels are clamped, Polaroid film has been shown to give good-quality resolution with reduced development time. At the conclusion of each case, we would suggest nephroscopic inspection of each calix to identify tiny residual fragments that might be missed on the final operative film. With direct visualization, these stones can be grasped effectively or irrigated out. A potential disadvantage to the use of any type of intraoperative localization technique is the possibility that an overly zealous attempt to remove tiny particles will cause unnecessary damage to the kidney. Small particles may pass spontaneously, and their presence is not always incompatible with achieving sterile urine and stable renal function.(ABSTRACT TRUNCATED AT 400 WORDS)

Computed tomography of acute renal failure secondary to rhabdomyolysis

Two patients with rhabdomyolysis and renal failure were imaged with CT. The presence of a striate nephrogram, nephromegaly, and perinephric fluid has not previously been described on CT. Although nonspecific, these findings suggest the diagnosis of acute tubular blockade, and, once identified, administration of additional urographic contrast medium should be avoided.

Extracorporeal shockwave lithotripsy: role of the radiologist

Extracorporeal shockwave lithotripsy (ESWL) is a new noninvasive treatment modality for urinary calculi. ESWL may be applied to the majority of patients requiring stone removal and is expected to replace, to a large degree, percutaneous stone removal (PSR), now practiced jointly by interventional radiologists and endourologists in most institutions. In a number of cases, ESWL and PSR will be complementary procedures. Technically, ESWL can be considered a radiologic procedure; thus far, radiologists are not participating in its use. In the authors' opinion, ESWL should be a combined urologic radiologic procedure analogous to PSR; this will allow the most rational and effective treatment.

Acute focal bacterial nephritis: a systematic approach to diagnosis and treatment

Acute focal bacterial nephritis, synonymous with acute lobar nephronia or focal nonliquefactive pyelonephritis, represents a localized area of renal inflammation. Clinically, acute focal bacterial nephritis presents as acute pyelonephritis but is distinguishable by the presence of a focal mass on excretory urography. The further distinction between acute focal bacterial nephritis and other renal masses is aided by the appropriate use of renal sonography and computerized tomography. The clinical and imaging manifestations in 9 patients with acute focal bacterial nephritis are described. Our experience coupled with a review of the literature suggests that a systematic approach to the diagnosis and management of acute focal bacterial nephritis allows for the most efficacious use of the noninvasive imaging modalities.

New self-developing film for intraoperative renal stone localization

The use of intraoperative radiography for localization of small renal calculi has been a valuable adjunct to surgery. Unfortunately, because of the considerable time required for mobilization of the kidney, the development of x-ray films and the not infrequent need for repeat exposures, considerable time can be added to the operation. We have found that the use of Polaroid film can give high-quality intraoperative radiographs. The main advantage of Polaroid film over the standard Kodak kidney film is that the film is developed in the operative suite and, in most cases, requires less than one minute.

Nephrolithiasis: current concepts in medical management

Advances in renal lithiasis research have contributed to a better understanding of the many varied factors that contribute to renal calculus formation. Utilizing the newer techniques of ambulatory metabolic evaluation, we can establish a specific diagnosis in 95% of recurrent stone-formers. Since a significant percentage of initial stone-formers will never have a second episode, it is essential to establish the natural history of the patient's stone disease prior to initiating potentially life-long medical therapy. The majority of initial stone-formers can be managed with education concerning modest dietary restrictions and increased fluid intake. For the recurrent stone-former with metabolically active stone disease, it is probably best to design medical therapy to treat the specific urinary chemical abnormality or disease process.

Imaging of urinary tract disease. Current approaches

Current modalities and techniques used in imaging of the urinary tract offer prompt and accurate diagnoses as well as treatment in some cases. Careful planning and judgement in the choice of the imaging sequence is important in avoiding redundant or ill-advised tests. Individual tailoring will be necessary in some patients. It is hoped that with the rational use of the diagnostic tools now available and with the continued improvement in MRI technology, safe and accurate diagnoses will be expected in practically all patients with diseases of the urinary tract.

Pyeloduodenal fistula

Twenty-eight cases of pyeloduodenal fistula are reviewed from the standpoint of pathogenesis, clinical presentation, diagnosis, and management. Our review suggests the majority of these fistulas involved the right kidney and occurred as a result of chronic renal inflammatory disease. The fistulas are most effectively diagnosed with retrograde pyelography. The review suggests the best management of pyeloduodenal fistula is nephrectomy and primary closure of the duodenum.

Use of coagulum for displaced ureteral calculi

At the time of distal ureterolithotomy the urologic surgeon is faced occasionally with the complication of a displaced ureteral calculus that has migrated proximally through a dilated ureter. We report such a case and offer an alternative method of injection and extraction of a cryoprecipitate coagulum through the ureterotomy. This technique may eliminate the need for an additional incision or a possible second operative procedure.

Bilateral complete ureteral obstruction secondary to an abdominal aortic aneurysm with perianeurysmal fibrosis: diagnosis by computed tomography

The sixteenth case of bilateral ureteral obstruction with anuria secondary to an abdominal aortic aneurysm with perianeurysmal fibrosis is presented. The details of this case clearly indicate the need for a combined vascular and urologic approach to patients with this disorder. A complete preoperative evaluation, including excretory urography, retrograde pyeloureterography, aortography and, when indicated, venacavography, may determine renal and vascular abnormalities that will allow a more definitive and successful management of this difficult problem. Furthermore, we believe that the use of computed tomography is an invaluable tool to define this retroperitoneal disease process and its precise relationship to the ureters.