Urolithiasis in a Patient Ingesting Pure Silica: A Scanning Electron Microscopy Study

A patient who repeatedly produced urinary calculi, had consumed about 3g of cristobalite (SiO2) per day for many years. Investigations using scanning electron microscopy revealed minute particles containing silicon in the core of the stone as well as in urine sediment. A mechanism similar to that proposed for the effect of silicon-containing drugs against gastric ulcer, may play a role in this formation of silicon-containing urinary stones

Experimental Investigation of the Genesis of Struvite Stones in Cats

Infrared spectroscopy of feline urinary stones revealed that struvite was the main constituent in 77.6 % of all concrements. However, only in 30.8% (16/52) of struvite stone patients were any infections of the urinary tract detected. Scanning electron microscopical comparison of non-infected feline struvite stones and human struvite concrements which had grown in the presence of infection revealed clear differences. All the feline struvite concrements were of coarse crystalline construction with the crystalline form typical of struvite. Traces of partial solution and stratification were frequently detected on the crystalline surfaces. The human struvite stones whose growth had been accompanied by infection did not display these features; the predominant structures in these concrements revealed very little evidence of any ordered growth. Examination of the urine and calculation of the relative supersaturation showed that where physiological pH values and physiological concentrations of lithogenic substances were present sterile urine can become supersaturated with struvite. The morphological peculiarities of the feline concrements and the results of urinary analysis indicate slow crystalline growth rates. Phases of growth alternate with periods of stagnation. This process may be influenced by dietary factors. In contrast to this, struvite stone formation in the presence of infection is characterised by rapid growth in continually supersaturated urine

Analysis of Canine Urinary Stones using Infrared Spectroscopy and Scanning Electron Microscopy

Infrared spectroscopic analysis of 741 canine urinary calculi revealed that struvite stones, 58% of the total, were the ones most commonly to be found. Cystine stone disease, 21%, is also of great significance for dogs, whereas calcium oxalate, urate and brushite calculi occur only seldom. 3 cases of xanthine stone formation were also noted. SEM examination revealed structures similar to human stones such as bipyramidal weddelIite, pseudomorphs from whewellite to weddellite, apatite deposits in cystine stones and characteristic mono-ammonium-urate needles. Other, unknown, structures were also discovered such as closely-knit intergrowths of cystine and brushite strata, mono-Na-urate and mono-K-urate intergrowths and Caurate. Of particular interest are the various forms of xanthine from compact spherical to lance-shapes in sheath-like arrangement

[Secondary malignancies in urinary diversions]

In contrast to ureterosigmoidostomy no reliable clinical data exist for tumor risk in different forms of urinary diversion using isolated intestinal segments.In 44 German urological departments, operation frequencies, indications, patient age, and operation dates of the different forms of urinary diversion, operated between 1970 and 2007, could be registered. The secondary tumors up to 2009 were registered as well and related to the numbers of the different forms of urinary diversions resulting in tumor prevalences.In 17,758 urinary diversions 32 secondary tumors occurred. The tumor risk in ureterosigmoidostomy (22-fold) and cystoplasty (13-fold) is significantly higher than in other continent forms of urinary diversion such as neobladders or pouches (p<0.0001). The difference between ureterosigmoidostomy and cystoplasty is not significant, nor is the difference between ileocecal pouches (0.14%) and ileal neobladders (0.05%) (p=0.46). The tumor risk in ileocecal (1.26%) and colonic neobladders (1.43%) is significantly higher (p=0.0001) than in ileal neobladders (0.5%). Of the 16 tumors that occurred following ureterosigmoidostomy, 16 (94%) developed directly at the ureterocolonic borderline in contrast to only 50% following urinary diversions via isolated intestinal segments.From postoperative year 5 regular endoscopic controls of ureterosigmoidostomies, cystoplasties, and orthotopic (ileo-)colonic neobladders are necessary. In ileocecal pouches, regular endoscopy is necessary at least in the presence of symptoms or should be performed routinely at greater intervals. Following neobladders or conduits, only urethroscopies for urethral recurrence are necessary