A Quantitative Histological Analysis of the Bladder in Classical Bladder Exstrophy in Various Stages of Reconstruction Utilizing Color Morphometry
The use of color image analysis to evaluate the contribution of collagen and smooth muscle in a given organ has been well described. We have recently reported on the subtypes of collagen found in normal neonatal bladders and in bladders of newborn exstrophy patients. Much debate continues in the Pediatric Urologic literature regarding the quality of the bladder in exstrophy patients. Despite what is believed to be adequate reconstruction in the exstrophy or epispadias patient, some children fail to attain a capacity required for the development of a satisfactory continence interval. The authors attempt to quantify using color morphometry, the relative amounts of collagen and smooth muscle in the exstrophic bladder at various stages of reconstruction and in newborn normal bladders
Materials and Methods
Bladder biopsies were obtained from the area just above the trigone in fifteen patients with classic bladder exstrophy and compared to sections obtained from nine neonatal bladders. All specimens were stained with Masson’s Trichrome technique, highlighting the extracellular matrix as blue and smooth muscle as red. All specimens were then analyzed using color image analysis system.
The collagen/smooth muscle ratio in control bladders was 0.36 ± 0.06. In those patients closed within one week of birth, the collagen/smooth muscle ratio was found to be 0.83 ± 0.46. In late closure and failed initial closure patients, the collagen smooth muscle ratio was 3.66 ± 2.3. In patients with undergoing bladder neck reconstruction the tissue/matrix ratio was 0.87 ± 0.39. These results indicate that compared with control bladder specimens, the bladder in exstrophy has an increased collagen to smooth muscle ratio. Delay in closure or failed initial closure is associated with a markedly increased COLL:SM ratio. However, once the bladder is successfully closed, the ratio returns to that level found at early closure prior to bladder neck reconstruction or augmentation.
Multiple factors are involved in the successful reconstruction of the exstrophy patient. Should dehiscence, chronic infections, multiple repairs (bladder closures and bladder neck reconstructions) etc. be minimized, their role determining which children will develop a satisfactory continence level may be eliminated. Therefore, the long term outcome in children born with classic bladder exstrophy may correlate most with the organization of smooth muscle and collagen as well as the type of collagen, rather than the relative amounts.
KeywordsBladder Neck Bladder Exstrophy Bladder Compliance Bladder Calculus Muscle Ratio
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