Continuous recording of urethral activity in healthy female volunteers

Abstract

The pressure variations at the maximal urethral closure pressure (MUCP) were continuously recorded in healthy female volunteers by means of a two-point microtip transducer catheter for one hour. Before the investigation a normal voiding was assured objectively and bladder instability was excluded.All women showed pressure variations both at the MUCP and more distally. The pressure variations, from 3 to 66 cm H20, showed rhythmicity and three frequency ranges could be identified. Slow pressure waves with a frequency of one in eight to 19 minutes were observed. Relatively fast-pressure waves were observed (one every one to four minutes) and relatively fast-frequency pressure waves were observed (rate: one to eight per minute).The pressure variations of the urethra seem to be an aspect of normal urethral physiology possibly contributing to continence and urinary tract infection prevention.

Pressure/cross-sectional area relations in the proximal urethra of healthy males Part III: The time dependent pressure response following forced dilation: standardization of a technique

“…in the high pressure zone, and may in part account for the variation found. Finally, biological variation is also an influence as it is known that the urethral pressure shows significant spontaneous oscillations which may very well have influenced the present measurements [20,26].…”

“…This was partly because it would prolong the total duration of the examination unacceptably for the subjects, but also because the pressure decay which may be neglected is likely to be so slow that it is of no or minimal physiological significance. Besides, it is uncertain whether extended relaxation takes place in vivo when the normal regulation mechanisms are intact, and extended evaluations of urethral pressure in men as well as in women have shown no signs of a prolonged stress-relaxation, even though significant fluctuations in urethral pressure are evident [20,26].…”

Changes in urethral resistance in the presence of detrusor activity

“…This suggests that the ''guarding'' is aberrant as there is a probable reduced urethral sphincter activity in the presence of detrusor overactivity. Loss of urethral resistance or urethral instability is a common finding in association with detrusor overactivity [19]. Wise et al [20] found a spontaneous fall in urethral pressure in 42% of patients with detrusor overactivity.…”

Urethral Instability: Current Pathophysiological Concept

“…Moreover, urethral pressure variations during filling cystometry are considered as an artefact and, therefore, of no relevance for explaining symptoms of patients by some investigators [2] . Slow-wave, rhythmic urethral pressure variations have been shown in healthy volunteers and may be an aspect of normal urethral physiology that could contribute to continence and prevention of urinary tract infection and need to be considered as pathophysiological [27] . McLennan et al [23] published on the significance of urethral pressure measurements during filling cystometry.…”