Urethral pressure variations in healthy male volunteers.

Urethral pressures are usually considered to be static and only few authors have emphasized time-related pressure changes. We conducted a study on 10 healthy male volunteers, monitoring the urethral pressures at maximal urethral closure pressure, 2.5 cm proximal (bladder neck) and 2.5 cm distal (pars bulbosa) respectively over 30 min periods. At the bladder neck only sporadic waves were seen. At maximal closure pressure almost permanent oscillations were found, the wavelengths and amplitudes showing big differences. At the pars bulbosa 2 persons showed only sporadic oscillations and in 7 we found permanent pressure variations. The pressure variations are proposed to represent peristaltic activity with the ability of expelling the last drops of urine after micturition and posing a mechanical barrier to ascending microorganisms.