Correlation of cystographic bladder morphology and neuroanatomy in boys with posterior urethral valves

Abstract

Purpose. We have observed a difference in the radiographic appearance of the body of the bladder (trabeculated) and its base (smooth) in boys with severely obstructing posterior urethral valves. We wanted to determine if (1) this was a reproducible finding and (2) there was an anatomic and/or physiologic explanation for it. Materials and methods. We reviewed the initial voiding cystourethrogram in 47 boys with severe posterior urethral valves. The interureteric ridge was used as the division between the body and base of the bladder. The presence of trabeculation for each region was recorded. Results. Ages ranged from 1 day to 6 years at the time of initial cystographic evaluation (median 14 days). The body of the bladder was trabeculated and the base smooth in 72 % (34 patients). In the remaining patients, both the body and base were smooth. In no patient was the base trabeculated. Conclusions. The cystographic morphology of the urinary bladder in boys with posterior urethral valves can be explained by its neuroanatomy. The body of the bladder, which contracts during voiding because of parasympathetic (cholinergic) stimulation, becomes trabeculated. The bladder base relaxes during voiding due to sympathetic (alpha adrenergic) stimulation and remains smooth. Thus, this difference in the cystographic appearance of the two parts of the urinary bladder reflects the normal innervation and the mechanics of micturition in boys with urethral obstruction.