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Abnormal Uterine Bleeding (AUB)

Abnormal uterine bleeding (AUB) is bleeding from the vagina that may occur at abnormal times or follow an unexpected pattern, such as:

It is also referred to as "dysfunctional uterine bleeding" (DUB).

What is Normal Uterine Bleeding?

Every woman's menstrual cycle, or period, is different. On average, a woman's period occurs every 28 days. Most women have cycles between 24 and 34 days apart. It usually lasts 4 - 7 days.

The endometrial lining of the uterus thickens each month to prepare for pregnancy. If a woman does not become pregnant, menstruation occurs and the endometrial lining is shed. This results in a limited amount of bleeding (an average of 80 ml or 5 Tablespoons).

The term "menorrhagia" is sometimes used to describe an abnormally heavy and prolonged menstrual period that occurs at regular intervals. Causes may be due to abnormal blood clotting, disruption of normal hormonal regulation of periods or disorders of the endometrial lining of the uterus. Depending upon the cause, it may be associated with "dysmenorrhea", especially painful menstrual periods.

Causes of Abnormal Uterine Bleeding

There are a variety of conditions that can lead to abnormal uterine bleeding. The most likely cause varies according to the age of the woman.

Pregnancy. Pregnancy is one of the most common causes of abnormal uterine bleeding. It may be complicated by an ectopic pregnancy or miscarriage.

Bleeding before a girl begins menstruation is always abnormal

It may be caused by trauma, a foreign body in the vagina (such as toilet paper), irritation of the genital area (due to bubble bath, infections), or urinary tract problems. Bleeding can also occur as a result of sexual abuse.

Irregular bleeding during the first few months of menstruation is common. This usually goes away without treatment as the menstrual cycle stabilizes. Further evaluation may be recommended if abnormal bleeding continues after several months.

Irregular ovulation or anovulation. Some women do not ovulate regularly, causing irregular hormone levels and intermittent light or heavy bleeding. Although anovulation is most common when periods first begin and just prior to menopause, it can occur at any time during the reproductive years.

Birth control pills. Girls and women who use hormonal birth control (oral contraceptive pills or patches) may experience "breakthrough bleeding" between periods. If this occurs during the first few months, it may be due to changes in the lining of the uterus. If it persists for more than a few months, evaluation may be needed and/or a different birth control pill may be recommended. Breakthrough bleeding can also happen if birth control is forgotten or taken late. In this situation, there is a risk that the woman could become pregnant if she has sex. Another form of birth control, such as a condom, is recommended if the pill/patch/shot is not taken on time.

Transition into menopause. Before menopause (the end of menstruation), a woman passes through a period called the menopausal transition or "perimenopause". During the menopausal transition, normal hormonal cycling begins to change and ovulation may be inconsistent. While estrogen secretion continues, progesterone secretion declines. These hormonal changes can cause the endometrium to grow and produce excess tissue, increasing the chances that polyps or endometrial hyperplasia (thickened lining of the uterus) will develop and potentially cause abnormal bleeding.

Uterine Disorders. Some women who ovulate normally experience excessive blood loss during their periods or bleed between periods. The most common causes of such bleeding are uterine fibroids or polyps. These irregular growths distort the shape of the uterus and lead to abnormal uterine bleeding.

Other causes of dysfunctional uterine bleeding includes:

Diagnosis of Abnormal Uterine Bleeding

There are several important variables to share when speaking to your doctor about abormal uterine bleeding, including:

Pelvic exam. A pelvic examination will be performed to look for any sources of bleeding and to examine the size and shape of the uterus. He or she will examine the cervix to look for signs of cervical bleeding, and a Pap smear may be obtained to examine the cells of the cervix.

Pregnancy test. A pregnancy test may be performed to rule out pregnancy as the cause of bleeding.

Laboratory tests. A culture of the cervix may be peformed to rule out an infection, particularly if there is an abnormal vaginal discharge. Blood tests, such as a complete blood count (CBC) thyroid function tests, may also be ordered. The blood test may show the presence of anemia that may be due to blood loss or other causes.

Hormonal to determine ovulatory status. Because hormonal irregularities can contribute to abnormal uterine bleeding, hormone levels may be test to determine whether ovulation occurs each monthly cycle.

Endometrial biopsy. An endometrial biopsy may be performed in women over age 35 to rule out endometrial cancer or abnormal endometrial growths. A biopsy may also be performed in women younger than 35 if they have risk factors for endometrial cancer. Risks include obesity, chronic anovulation, history of breast cancer, tamoxifen use or a family history of breast cancer or colon cancer. During the biopsy, a thin instrument is inserted through the vagina into the uterus to obtain a small sample of endometrial tissue. The biopsy can be performed without anesthesia.

Transvaginal ultrasound. In a transvaginal ultrasound, a small ultrasound probe is inserted into the vagina so that it is closer to the uterus and can provide a clear image of the uterus.

Sonohysterography. In this test, a transvaginal ultrasound is performed after sterile saline is instilled into the uterus. This procedure gives a better picture of the inside of the uterus, and small lesions can be more easily detected. However, because tissue samples cannot be obtained during the procedure, a final diagnosis is not always possible and additional evaluation, usually including hysteroscopy with dilation and curettage (D&C) may be necessary.

MRI. A magnetic resonance image (MRI) is a non-invasive test that is sometimes used to determine if fibroids or other structural abnormalities of the uterus are present.

Hysteroscopy. During hysteroscopy, a small scope is inserted through the cervix and into the uterus. Air or fluid is injected to expand the uterus and to allow the physician to see the inside of the uterus. Tissue samples may be taken. Anesthesia is used to minimize discomfort during the procedure. In most cases, hysteroscopy is performed along with a D&C.

Dilation and curettage (D&C). In a D&C, the cervix or opening of the uterus is dilated and instruments are inserted and used to remove endometrial or uterine tissue. A D&C usually requires anesthesia. It can sometimes be used as a treatment for prolonged or excessive bleeding that is due to hormonal changes and that is unresponsive to other treatments.

Treatment Options for Abnormal Uterine Bleeding

The treatment of abnormal bleeding is based upon the underlying cause.

Birth control pills. Birth control pills are often used to treat uterine bleeding that is due to hormonal changes or hormonal irregularities. Birth control pills may be used in women who do not ovulate regularly to establish regular bleeding cycles and prevent excessive growth of the endometrium. In women who do ovulate, they may be used to treat excessive menstrual bleeding.

During the menopausal transition, birth control pills or other hormonal therapy may be used to regulate the menstrual cycle and prevent excessive growth of the endometrium.

Nonsteroidal anti-inflammatory drugs (NSAIDS), such as  ibuprofen (Advil) naproxen (Aleve, Naprosyn) may be helpful in reducing blood loss and cramping in these women.

Progesterone (Progestin). Progesterone is a hormone made by the ovary that is effective in preventing excessive bleeding in women who do not ovulate regularly. Progestins are usually given as pills (medroxyprogesterone acetate, norethindrone) and are taken once-a-day for 10-12 days each month or two. Progestins can be taken for longer periods if there has been overgrowth of the uterine lining. Vaginal bleeding will begin before the seventh day of progestin treatment if the uterine lining is overgrown, but it may not be seen until several days after the last progestin tablet is taken. In some cases, the progestin is given every few months to prevent excessive growth of the uterine lining and heavy menstrual bleeding.

Progestins may also be given in other ways, such as in an injection, an implant, or an intrauterine device.

Intrauterine device (IUD). An intrauterine contraceptive device (IUD) that secretes progestin, such as Mirena, may be recommended for women who do not ovulate regularly. IUDs are inserted by a healthcare provider through the vagina and cervix into the uterus. Most are made of molded plastic and include an attached plastic string that projects through the cervix, enabling the woman to check that the device remains in place

Progestin-releasing IUDs decrease menstrual blood loss by 40-50% and decrease pain associated with periods. Some women completely stop having menstrual bleeding as a result of the IUD, which is reversible when the IUD is removed.

Surgery. Surgery may be necessary to remove uterine tissue, due to fibroids or polyps. Women who have completed childbearing and have heavy menstrual bleeding can consider a surgical procedure such as endometrial ablation. This procedure is done while the woman is under general or regional anesthesia, and uses heat, cold, or a laser to destroy the lining of the uterus.


Reference: National institutes of Health

Last updated March 7, 2017