[Silica urolithiasis: report of a new case]. / Litiasis urinaria de sílice: aportación de un nuevo caso.

We report a new case of silica urolithiasis in a 71-year-old patient with background of medicament ingesta (antacid) which could justify the formation of these calculi with so uncommon composition. Medicament calculi amounts about 1% from total urinary calculi. Among them, silica ones (silicon dioxide or Si O2) have been relate din their etiology to chronical ingest of antacid drugs, specially those with magnesium trisilicate. Silica formation in urine is facilitated and conditioned by an acid pH of it. Diagnosis and therapeutical approach does not change in relation to other lithiasis with similar dimension or location. After its composition report, and ruling out the possibility for patient's malingering, urine alkalinization was applied, with an excellent follow-up afterwards. The antacid was substituted by other drug. We analyze the most important aspects about this case. We also make reference to the main related bibliography.

Litiasis urinaria de sílice: aportación de un nuevo caso / Silica urolithiasis: report of a new case

Presentamos un nuevo caso de litiasis urinaria de sílice en un paciente varón de 71 años con antecedentes de ingesta medicamentosa (antiácido) que pudiera justificar la formación de estos cálculos de composición poco común. Los cálculos medicamentosos constituyen aproximadamente un 1 por ciento del total de cálculos urinarios. Dentro de estos, los de sílice (dióxido de silicio o Si O2) han sido relacionados en cuanto a su etiología con la ingesta crónica de fármacos antiácidos, especialmente aquellos que contienen trisilicato de magnesio. La formación de sílice en orina estaría facilitada y condicionada a la presencia de valores ácidos en su pH. El diagnóstico de la litiasis y su enfoque terapéutico no varía con respecto a otros cálculos de similares dimensiones y localización. Tras el informe de su composición, y descartando simulación por parte del paciente, fue instaurada alcalinización urinaria, con una evolución posterior excelente. El antiácido fue sustituido por otro medicamento. Analizamos los aspectos más importantes acerca del caso. Hacemos referencia asimismo a la bibliografía más destacada (AU)

No disponible

[Double J ureteral catheter. Clinical complications]. / El catéter ureteral doble J. Complicaciones clínicas.

OBJECTIVE: To analyze the clinical complications of double-J ureteral catheters. METHODS: The most relevant studies published in the literature since the self-retaining indwelling catheter was first described in 1967 are reviewed. RESULTS: The experience and results reported in the most relevant studies are presented. CONCLUSIONS: The double-J ureteral stent has become an integral part of the urological armamentarium. It allows good urinary drainage from the kidney to the bladder and is generally safe and well-tolerated. However, different complications may occur with short- or long-term use of indwelling stents. These complications vary from minor side effects such as hematuria, dysuria, frequency, flank and suprapubic pain, to major complications such as vesico-ureteric reflux, stent migration, encrustation, urinary infection, stent fracture, necrosis and ureteral fistula. Most of these complications require removal of the catheter.

[In vitro study of the process of urinary calculi fragmentation with endoscopy, light microscopy, and scanning electron microscopy]. / Estudio in vitro del proceso de fragmentación de los cálculos urinarios con endoscopia, microscopio óptico y microscopio electrónico de barrido.

Stones with different compositions respond differently to shock wave lithofragmentation. Likewise, the various lithotrity systems used may have different effects on the stones. To determine the relationships between stone composition and their fragmentation patterns, we conducted an in vitro study using endoscopy, magnifying glass, light microscope and scanning electron microscope on fragments obtained after lithotrity of 60 pure stone with different compositions: calcium oxalate monohydrate and dihydrate (OXMH and OXDH), phosphocarbonate (PC), ammonium magnesium phosphate (AMF) and uric acid (UA). Fragmentation was carried out with 4 different lithofragmenting sources (electrohydraulic, piezoelectric, ultrasound and pulse laser). No morphologic differences in the fractures induced by the various lithofragmenting sources were demonstrated. OXMH and UA stones basically break up by intercrystalline fracture and splitting of their concentric plates. OXDH breaks up mainly by intercrystalline fractures aided by the fibrillar organic material and phosphocarbonates found in the intercrystalline spaces. Fragmentation in infective stones (AMF and PC) occurs across the intercrystalline surfaces and by intracrystalline fracture. Ammonium urate fragments break up by intracrystalline fractures that run across the equatorial plane of its characteristic acicular microspheres.

[The proximal migration of a double-J catheter. A review of the predisposing factors. Apropos a case]. / Migración proximal del catéter doble-J. Revisión de factores predisponentes. A propósito de un caso.

Case report of a patient bearer of a double-J ureteral catheter due to ureteral lithiasis. After persistent renoureteral pain and fever, the proximal migration of the catheter is confirmed radiologically. The predisposing factors for this complication, described in the literature, are reviewed.

[Radiopacity of double-J ureteral catheters. Computed tomography quantification and clinical implications]. / Radiopacidad de los catéteres ureterales Doble-J. Cuantificación por T.A.C. e implicaciones clínicas.

OBJECTIVE: To determine whether knowledge about the degree of radiopacity of the double-J ureteral catheters utilized in Spanish hospitals suffices for correct radiologic control and subsequent follow-up. METHODS: The CT attenuation index was utilized to determine the degree of radiopacity of 23 double-J ureteral stents, comprised of different biomaterials and from different manufacturers, that are used in Spanish hospitals. RESULTS: The values ranged from 1,000-3,070 Hounsfield units. CONCLUSION: All the catheters analyzed were sufficiently radiopaque to permit good radiologic control during insertion and subsequent follow-up. The radiopacity of the stent depends on the metal salt employed during the manufacturing process and not on the biomaterial.

[In vitro study of urinary calculi fragmentation with 4 different systems of lithofragmentation]. / Estudio in vitro de la fragmentación de los cálculos urinarios con cuatro sistemas de litofragmentación diferentes.

The results of shockwave lithofragmentation are conditioned by stone composition. Similarly, the different types of lithofragmenting energy can have different effects on the calculi. The purpose of this experimental study is to establish a relationship between calculi composition and type of energy used for fragmentation, with the results of the lithotriptsy treatment. 60 calculi, 12 for each pure composition selected (calcium oxalate mono and dihydrate, phosphocarbonate, ammonium magnesium phosphate and uric acid) underwent in vitro lithofragmentation with 4 different lithofragmenting sources (electrohydraulic, piezoelectric, ultrasound and pulsed laser). It was carried out a study of fragmentation in particles under 3 mm and pulverization in particles under 0.5 mm, analyzing post-lithotriptsy fragments with scanning electron microscopy associated to X-ray dispersion energy. No relationship was shown between calculi composition and amount of energy supplied for the fragmentation. The lithiasic composition correlates to the fragmentation pattern, so that oxalocalcium calculi undergoes good fragmentation and poor pulverization, infective calculi have poor fragmentation but good pulverization and uric acid calculi show poor fragmentation and pulverization.

[In vitro study with techniques of imaging of the composition of urinary calculi]. / Estudio in vitro mediante técnicas de imagen de la composición de los cálculos urinarios.

Pre-treatment knowledge of the lithiasic composition can be useful to design the most appropriate therapeutic scheme for each kind of stone. The relationship between the stone's densitometry information provided by the different imaging techniques, conventional radiology (RX), computerized axial tomography (CAT) and dual energy radiographic densitometry (DO) is analyzed, as well as the elemental composition determined by the microanalysis of fragments obtained post-lithotrity using a scanning electronic microscope (SEM) associated to X-ray dispersion energy (XDE). 60 stones, 12 for each pure composition selected (calcium oxalate mono and dihydro, phosphocarbonate, magnesium ammonium phosphate and uric acid), were studied with XR, CAT and DO and were later subjected to lithofragmentation in vitro. Fragments analysis was carried out post-lithotrity with SEM associated to XDE. The X-ray does not allow to establish the composition of some calculi. CAT quantifies the mineral contents of the oxalocalcic and infective calculi and differentiates the uric acid from the other compositions because the mean density values are under 500 Hounsfield Units. DO evaluates the lithiasic content in phosphocarbonate salts which are structurally similar to bone hydroxyapatite.

[Changes in physical characteristics of endourologic catheters caused by shock waves]. / Modificaciones de las características físicas de los catéteres endourológicos inducidas por la onda de choque.

OBJECTIVE: To analyze the shock wave effects on double-J stent. METHODS: Retention strength modifications induced by shock waves were analyzed: a) 60 double-J stents obtained from patients were compared (20 had not been treated by ESWL; 20 had been treated by piezoelectric-ESWL and 20 by electrohydraulic-ESWL; b) the effects of piezoelectric-ESWL were determined in vitro using 36 stress-tested double-J stent segments (Urosoft, C-Flex and silicone) vs. a control group. RESULTS: The retention strength of the stents from ESWL-treated patients, especially those that had been submitted to piezoelectric-ESWL, was lower than in stents from patients that had not undergone ESWL (p < 0.05). The foregoing has been corroborated by the in vitro findings. The impact frequency causing maximum damage is specific for each material. Microphotographic studies revealed fracture lines on the surfaces of the ESWL-treated stents (Urosoft and C-Flex). CONCLUSIONS: The foregoing findings may explain the high incidence of double-J stent migration observed in ESWL-treated patients.

[Hydrodynamic behavior of endourologic catheters]. / Comportamiento hidrodinámico de los catéteres endourológicos.

OBJECTIVE: The present study analyzed the hydrodynamic behaviour of the double-J stent. METHODS: Thirty-two double-J stents of different sizes and biomaterials (16 new and 16 removed from patients) were hydrodynamically evaluated using two models: a) nephroureterocystectomy surgical blocks harvested from pigs and b) an in vitro experimental model of the upper urinary tract. The following parameters were measured: initial and final weights, encrusted material weight, inside and outside diameters, number, size and distribution of sideholes, wall thickness, drainage area and length of time the catheter was indwelling in the patient. RESULTS: Double-J stent placement in a normal upper urinary tract constitutes a partial obstruction that is proportional to the caliber of the catheter. Ureteral-flow reduction is 83%, 61% and 58% for 5FR, 6FR, and 7FR catheters, respectively. Extraluminal obstruction of the catheter reduces ureteral flow more than intraluminal obstruction (74%, 43% and 25% for extraluminal versus 83%, 66%, 57% for intraluminal for 5FR, 6FR and 7FR, respectively). Vesicoureteral and vesicorenal reflux pressures were 6.2 +/- 0.3 cm H2O and 35.2 +/- 2 cm H2O, respectively. CONCLUSION: Selection of a double-J stent must be individualized on the basis of indication, time indwelling, sex and route of insertion.

[Comparative analysis of lithiasic fragmentation induced by extracorporeal and direct contact sources]. / Análisis comparativo de la fragmentación litiásica inducida por las fuentes extracorpóreas y de contacto directo.

An in vitro experimental study on stone fragmentation was conducted on 114 calculi analyzed by infrared spectrophotometry. Four energy sources were utilized: electrohydraulic, piezoelectric, ultrasound and pulsed laser. We analyzed stone susceptibility to fragmentation (particles < 3 mm), pulverization (particles < 1 mm) and stone fragility (amount of energy/mg of calculus fragmented into particles < 3 mm) for each type of energy source of each of the following 6 stone compositions: calcium oxalate monohydrate, calcium oxalate dihydrate, magnesium ammonium phosphate, phosphate carbonate, uric acid and phosphate oxalate. The calcium oxalate dihydrate calculi were the most susceptible to fragmentation and the infective calculi (magnesium ammonium phosphate and phosphate carbonate) were the most susceptible to pulverization. The piezoelectric energy showed the highest capacity for fragmentation and pulverization of calculi. Stone fragility depended on each stone type and the energy source utilized.

[An unusual lithiasic nidus. Review of bladder lithogenesis caused by foreign bodies]. / Un inusual nido litiásico. Revisión de la litogénesis vesical por cuerpo extraño.

We report on an 88-year-old male patient with a bladder stone that had been incidentally detected and found to contain a foreign body, which was shown to be a urethral dilator on microscopic and chemical analyses. The calculi had three well-defined layers with clearly infective features. The literature on bladder stone formation is reviewed and the clinical features and treatment are discussed.