Cystourethrograms characteristic of bladder instability in children.

Cystourethrograms characteristic of bladder instability are illustrated. A repeated increase of intravesical pressure causes functional and morphologic deformities of vesicourethral configuration: ballooning of the proximal urethra, ureteric reflux, and trabeculated bladder during the storage phase; and dilatation of bladder neck and proximal urethra, and a pearl string-like configuration of urethra during the voiding phase. The clinical significance of these observations is presented.