Bladder wall abnormalities in myelodysplastic bladders: a computer assisted morphometric analysis

Myelodysplasia represents the most common cause of neurogenic bladder dysfunction in children. The specific histological features associated with myelodysplastic bladders have not been previously characterized. Our objective was to study the relationship between smooth muscle and connective tissue in control and myelodysplastic bladders using classical morphometric analysis with the assistance of an automated image analysis system. Gross histological analysis of the bladder specimens of normal stillborn fetuses showed organized muscle bundles embedded in a small amount of connective tissue. The bladder specimens of myelomeningocele stillborn fetuses showed a marked paucity of muscle bundles as well as a significantly diminished size of the muscle bundles. The myelomeningocele bladder specimens obtained from patients undergoing autopsy and those undergoing augmentation cystoplasty revealed significant interfascicular and pericellular infiltration of the smooth muscle by dense connective tissue. Quantitative morphometric analysis showed that the myelomeningocele stillborn fetuses have a significant increase in the volumetric content of connective tissue compared to control stillborn fetuses. The bladders of myelomeningocele patients who underwent autopsy or augmentation cystoplasty had a 3-fold increase in connective tissue when compared to normal controls. These findings reveal that structural changes in the histological components of the myelodysplastic bladder can be demonstrated not only in patients of varying ages undergoing autopsy or augmentation cystoplasty but also in the developing fetus. These findings enhance our understanding of the relationship of connective tissue proliferation to smooth muscle in the myelodysplastic bladder. We discuss the relationship of these findings to pathological detrusor morphology and detrusor dysfunction.