Some common menstrual abnormalities include
Irregular or absent menses and nonmenstrual vaginal bleeding have many causes. In women of reproductive age, pregnancy should always be suspected.
Abnormal vaginal bleeding Vaginal Bleeding Abnormal vaginal or uterine bleeding includes Menses that are excessive in frequency (amenorrhea, oligomenorrhea, polymenorrhea), volume, or duration (menorrhagia, or heavy menstrual bleeding)... read more in nonpregnant women is evaluated differently from vaginal bleeding in pregnant women (see Vaginal Bleeding During Early Pregnancy Vaginal Bleeding During Early Pregnancy Vaginal bleeding occurs in 20 to 30% of confirmed pregnancies during the first 20 weeks of gestation; about half of these cases end in spontaneous abortion. Vaginal bleeding is also associated... read more and Vaginal Bleeding During Late Pregnancy Vaginal Bleeding During Late Pregnancy Bleeding during late pregnancy (≥ 20 weeks gestation, but before birth) occurs in 3 to 4% of pregnancies. Some disorders can cause substantial blood loss, occasionally enough to cause hemorrhagic... read more ).
Polycystic ovary syndrome Polycystic Ovary Syndrome (PCOS) Polycystic ovary syndrome is a clinical syndrome typically characterized by anovulation or oligo-ovulation, signs of androgen excess (eg, hirsutism, acne), and multiple ovarian cysts in the... read more 
can cause some of the same symptoms as menstrual abnormalities.
Pelvic congestion syndrome Pelvic Congestion Syndrome Pelvic congestion syndrome is chronic pain exacerbated by standing or sexual intercourse and associated with varicose veins in or near the ovaries. Pelvic congestion syndrome is a common cause... read more , a common cause of chronic pelvic pain, is sometimes accompanied by abnormal menstrual bleeding.
(For a description of the menstrual cycle, see Menstrual Cycle Menstrual Cycle Hormonal interaction between the hypothalamus, anterior pituitary gland, and ovaries regulates the female reproductive system. The hypothalamus secretes a small peptide, gonadotropin-releasing... read more .)
