Urethral instability as an important element of dysfunctional voiding

We monitored detrusor and urethral behavior during bladder filling in girls with dysfunctional voiding (incomplete perineal relaxation) to determine the causes of this pathological condition.

In 15 girls without neuropathy but with a staccato voiding pattern in whom symptoms of urinary tract infection and urge incontinence were refractory to treatment we recorded urethral and bladder pressure, and anal sphincter needle electromyography throughout slow bladder filling.

Urethral instability was observed in 8 of the 15 girls as urethral pressure decreases with short periods of electromyography silence (6) or as intermittent urethral pressure increases with short perineal spasms (2). Detrusor instability was noted in 12 girls, while bladder pressure was normal in 1 and hypoactive in 2. In 6 cases of an unstable bladder urethral pressure decreases with silent electromyography periods were also noted. In 1 case low basic urethral pressure had short periods of increased pressure with electromyography bursts. In another case high compliance bladder uninhibited sphincter contractions were noted throughout filling.

Dysfunctional voiding is a misleading term since a pathological condition is also present during the bladder filling phase. Frequently observed detrusor and urethral instability may explain the urge sensation during filling and the staccato voiding phase.