The way to distinguish between menstruation and bleeding is as follows: 1. Regularity, most women have their periods very regularly and will come when the time comes. In contrast, vaginal bleeding is not regular and may occur on a day when there is sudden vaginal bleeding. 2. The amount of menstruation, for normal women, is more on the 2nd and 3rd day of menstruation and will gradually decrease, while vaginal bleeding does not have such regularity. 4. Vaginal bleeding does not have such clinical manifestations.