In order to define abnormal vaginal bleeding we must first understand normal vaginal bleeding. A normal menstrual cycle occurs between every 21 to 35 days. Menstrual cycles that last between 3-7 days are considered normal. Any thing outside of this range would fit the definition of abnormal vaginal bleeding. Abnormal vaginal bleeding can be bleeding that is too frequent, lasts for too long, is too heavy, or is infrequent. Any of these abnormalities deserves to be evaluated.
The interval of a menstrual cycle is counted as the first day of bleeding until the first day of the next bleeding episode. Cycle length can vary between women and can even vary each month in the same woman. Normal cycle interval is from 21 days to 35 days. A 28 day menstrual cycle is considered the typical cycle. In an “ideal” cycle bleeding lasts for 5 days, ovulation occurs on day 14 and the entire cycle is 28 days. Very few women have this “ideal” cycle regularly. It is much more common for there to be variation in both length of bleeding and cycle length in any individual from month to month.
The actual quantity of blood loss is hard for people to judge. Women typically do not have anyone to compare their cycles to. Studies have shown that women that rate their normal cycles as “heavy” did not loose any more blood on average than women who rated their cycles as “light”. A change from an individual’s normal pattern may be significant. If a women has a period that is greatly different than her normal experience, she deserves an evaluation.
Women that have bleeding outside of the normal ranges should be evaluated. Periods that are too long, too heavy, too frequent, or not frequent enough can all be signs of a problem that needs to be treated. Women should seek care for any of these problems. A menstruation that significantly different from the individual’s normal pattern could also be cause for concern and should be evaluated.
Infrequent menstrual cycles can also be of concern. A woman that goes more than 3 months without a menstrual cycle should be evaluated. Infrequent menstruation is a risk factor for uterine cancer and for significant hemorrhage. If a woman is having infrequent bleeding because she is being treated with a medication or birth control device that stops the period from coming, this is safe. Examples of this are continuously dosed birth control pills, the Mirena IUD, and the birth control implant.
Intramenstrual bleeding, bleeding between periods, is not normal and should be evaluated. Postcoital bleeding is bleeding during or after sex. This is not normal and could be caused by an infection or an abnormality of the cervix. This should be evaluated as well.