Devices and systems for facilitating the flow of menses through the cervix and for shortening the duration of menstruation include a pressure oscillations generating unit insertable into a vagina and configured for delivering pressure oscillations and/or acoustic waves and/or shock waves to the vagina and cervix to change the flow properties of menses fluid. The pressure oscillations generating unit may include one or more vibratable or movable members for generating pressure oscillations which may be powered by an internal or external power source. The devices may optionally include an absorbing member or a menses collecting member. A method of menstruation duration shortening includes placing the device within the vagina and applying pressure oscillations to the vagina or to a vaginal chamber formed within the vagina for increasing the flow rate of menses and shortening menstruation duration.