Abnormal Uterine Bleeding

Abnormal bleeding at a glance

  • Abnormal bleeding is defined as excessive menstrual bleeding, or as bleeding between periods, after sex or after menopause.
  • A hormone imbalance is the most common cause of abnormal bleeding, although other causes include pregnancy, miscarriage, some birth control methods, blood clotting disorders, and a number of uterine problems.
  • Abnormal bleeding is very common and can occur at any time in life, although certain causes and factors are age related.
  • Diagnosis options range from simple techniques such as taking a patient’s medical history, to visual examination of the uterus through a scope.
  • Treatments range from hormone medication prescriptions to surgery.

What is abnormal uterine bleeding?

In a normal menstrual cycle, a woman’s uterus discharges the equivalent of a few tablespoons of blood through the vagina over several days. This is normal uterine bleeding. In contrast, abnormal uterine bleeding is defined as bleeding in significant excess of this amount, or as bleeding between menstrual periods, after sex, for longer than usual, or after menopause.

For several reasons, the definition of “normal” menstrual periods and bleeding takes a broad range of factors into account.

A woman’s menstrual cycle begins at the first day of bleeding (the menstruation period) and ends with the first day of the next period. A normal cycle is usually 28 days long, but it is very common for the length of the menstrual cycle to vary over a woman’s reproductive years.

For example, a teenage girl may experience irregular cycles that become more regular with time. As a woman approaches age 35, she may experience increasingly shorter cycles.

As a woman nears and enters menopause (normally in her late 40s and early 50s), she may skip periods all together; at the same time, the bleeding may also become either lighter or heavier.

Taking these factors into account, doctors generally consider menstrual cycles abnormal if they are shorter than 21 days or longer than 35 days, or if there are other irregularities, which may be signs of a number of health conditions.

Causes of abnormal uterine bleeding

For most women, a hormone imbalance is the cause of abnormal uterine bleeding. In these cases, doctors classify the problem as dysfunctional abnormal bleeding (DUB). This kind of bleeding is more common in teens or in women approaching menopause.

Other causes of abnormal uterine bleeding include:

  • Pregnancy
  • Some birth control methods, including an intrauterine device (IUD) or birth control pills
  • Excessive thickening of the uterine lining, called endometrial hyperplasia.
  • Problems with blood clotting from disorders such as von Willebrand’s disease and platelet abnormalities
  • Uterine fibroids or polyps, irregular growths and benign tumors
  • Thyroid problems
  • Ectopic pregnancy, in which a fertilized egg does not reach the uterus for normal development
  • Miscarriage
  • Cancer of the uterus, cervix or vagina

Age-related factors

Abnormal bleeding can occur at any time in life, although certain causes tend to be age related.

  • Young girls may experience bleeding before their first period (called menarche) due to trauma and injury, a foreign body, genital irritation, urinary tract problems, or sexual abuse.
  • Adolescents often experience abnormal bleeding for several months, or even years, after menarche.
  • Young women sometimes do not release an egg from their ovaries (ovulate) during a cycle, creating a hormone imbalance. The body’s estrogen thickens the uterine lining (the endometrium) more than usual, and when the uterus discharges the lining during menstruation (a woman’s period), the bleeding can be quite heavy.

The same hormone imbalance may confuse the body as to when to shed the endometrium, causing spotting between periods.

  • Premenopausal women in their 40s and 50s may skip some months of ovulation, causing irregular menstrual flow – some months may bring heavy bleeding, while other months are much lighter than usual. Women in this age group also undergo a thickening of the endometrium. Because this thickening is sometimes a sign of uterine cancer, women in this age group who notice abnormal bleeding should consult with a doctor.
  • Post-menopausal women can experience abnormal bleeding as a result of hormone replacement therapy.Other causes after menopause include:
    • Polyps or fibroids
    • Uterine infection
    • Excessive thinning of the tissue lining the vagina and uterus
    • Use of blood thinners and anticoagulants
    • Side effects of radiation therapy
    • Endometrial hyperplasia, or unusual/excessive cell growth in the endometrium
    • Endometrial cancer

Learn more about abnormal uterine bleeding diagnosis and treatment