Menstrual abnormalities include
Irregular or absent menses and nonmenstrual vaginal bleeding have many causes, but in women of reproductive age, pregnancy should always be suspected.
Abnormal vaginal bleeding in nonpregnant women is evaluated differently from vaginal bleeding in pregnant women (see Vaginal Bleeding During Early Pregnancy and Vaginal Bleeding During Late Pregnancy).
Polycystic ovary syndrome can cause some of the same symptoms as menstrual abnormalities.
Pelvic congestion syndrome, a common cause of chronic pelvic pain, is sometimes accompanied by abnormal menstrual bleeding.
(For a description of the menstrual cycle, see Menstrual Cycle.)