INTRODUCTION

The inside of the uterus has two layers. The thin inner layer is called the endometrium. The thick outer layer is the myometrium (myo = muscle) (figure 1). In women who menstruate, the endometrium thickens every month in preparation for pregnancy. If the woman does not become pregnant, the endometrial lining is shed during the menstrual period. After menopause, the lining normally stops growing and shedding.

Under normal circumstances, a woman's uterus sheds a limited amount of blood during each menstrual period (less than 5 tablespoons or 80 mL). Bleeding that occurs between menstrual periods or excessive menstrual bleeding is considered to be abnormal uterine bleeding. Once a woman who is not taking hormone therapy enters menopause and the menstrual cycles have ended, any uterine bleeding is considered abnormal.

Abnormal uterine bleeding can be caused by many different conditions. This topic review discusses the possible causes of abnormal bleeding, how it is evaluated, and various treatment strategies that may be recommended.

CAUSES OF ABNORMAL UTERINE BLEEDING

Most conditions that cause abnormal uterine bleeding can occur at any age, but some are more likely to occur at a particular time in a woman's life.

Abnormal uterine bleeding in young girls — Bleeding before menarche (the first period in a girl's life) is always abnormal. It may be caused by trauma, a foreign body (such as toys, coins, or toilet tissue), irritation of the genital area (due to bubble bath, soaps, lotions, or infection), or urinary tract problems. Bleeding can also occur as a result of sexual abuse.

Adolescents — Many girls have episodes of irregular bleeding during the first few months after their first menstrual period. This usually resolves without treatment when the girl's hormonal cycle and ovulation normalizes. If bleeding persists beyond this time, or if the bleeding is heavy, further evaluation is needed.

Abnormal bleeding in this age group can also be caused by any of the conditions that cause bleeding in all premenopausal women, including: pregnancy, infection, and bleeding disorder or other medical illnesses. These and other causes are discussed in the next section.

Premenopausal women — Many different conditions can cause abnormal bleeding in women between adolescence and menopause. Abrupt changes in hormone levels at the time of ovulation can cause vaginal spotting, or small amounts of bleeding. Breakthrough bleeding can also occur in premenopausal women who use hormonal birth control methods.

Some women do not ovulate regularly and may experience intermittent light or heavy vaginal bleeding. Although anovulation is most common when periods first begin and during perimenopause, it can occur at any time during the reproductive years. (See "Patient information: Absent or irregular periods (Beyond the Basics)".)

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 and benign tumors are composed of uterine tissue that distort the structure of the uterus and lead to abnormal uterine bleeding. Fibroids and polyps can also occur in anovulatory women. (See "Patient information: Uterine fibroids (Beyond the Basics)" and "Patient information: Menorrhagia (excessive menstrual bleeding) (Beyond the Basics)".)

Other causes of abnormal uterine bleeding in premenopausal women include:

• Pregnancy
• Cancer or precancer of the cervix or the endometrium (lining of the uterus) (see "Patient information: Endometrial cancer diagnosis and staging (Beyond the Basics)")
• Infection or inflammation of the cervix or endometrium
• Clotting disorders such as von Willebrand disease, platelet abnormalities, or problems with clotting factors
• Medical illnesses such as hypothyroidism, liver disease, or chronic renal disease

Hormonal birth control — Girls and women who use hormonal birth control (eg, pills, ring, shot, patch) 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. (See "Patient information: Hormonal methods of birth control (Beyond the Basics)".)

Breakthrough bleeding can also happen if a hormonal birth control method 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 (eg, condoms) is recommended if the pill/patch/shot is not taken on time.

Women in the menopausal transition — Before the menstrual periods end, a woman passes through a period called the menopausal transition. 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.

Women in the menopausal transition are also at risk for other conditions that cause abnormal bleeding, including cancer, infection, and bodywide illnesses. Further evaluation is needed in women with persistent irregular menstrual cycles or an episode of profuse bleeding.

Women in the menopausal transition still ovulate some of the time and can become pregnant; pregnancy can cause abnormal bleeding. In addition, women in perimenopause may use hormonal birth control medications, which can cause breakthrough bleeding.

Menopausal women — A number of conditions can cause abnormal bleeding during the menopause. Women who take hormone replacement therapy may experience cyclical bleeding. Any other bleeding that occurs during menopause is abnormal and should be investigated. Causes of abnormal bleeding during menopause include:

• Atrophy (excessive thinning) of the tissue lining the vagina and uterus
• Cancer of the uterine lining (endometrium) (see "Patient information: Endometrial cancer diagnosis and staging (Beyond the Basics)")
• Polyps or fibroids
• Endometrial hyperplasia
• Infection of the uterus
• Use of blood thinners or anticoagulants
• Side effects of radiation therapy

ABNORMAL UTERINE BLEEDING EVALUATION

Initial assessment — While taking a woman's medical history, a clinician will review the duration and amount of bleeding; factors that seem to bring the bleeding on; symptoms that occur along with the bleeding such as pain, fever, or vaginal odor; if bleeding occurs after sexual intercourse; whether there is a personal or family history of bleeding disorders; the woman's medical history and medications she is taking; recent weight changes, stress, a new exercise program, or underlying medical problems.

The clinician will perform a physical examination to evaluate the woman's overall health, and a pelvic examination to confirm that the bleeding is from the uterus and not from another site (eg, the external genitals or rectum). During the pelvic exam, the clinician will look for any obvious lesions (cuts, sores, or tumors) and will 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 (the lower end of the uterus, where it opens to the vagina). (See "Patient information: Cervical cancer screening (Beyond the Basics)".)

Lab tests — In premenopausal women, a pregnancy test is performed. If there is any abnormal vaginal discharge, a cervical culture may be performed. Blood tests may also be done to determine if there are problems with blood clotting or other bodywide conditions, such as thyroid disease, liver disease, or kidney problems.

Tests to determine ovulatory status — Because hormonal irregularities can contribute to abnormal uterine bleeding, testing may be recommended to determine if the woman ovulates (produce an egg) during each monthly cycle.

Endometrial assessment — Tests that assess the endometrium (lining of the uterus) may be performed to rule out endometrial cancer and structural abnormalities such as uterine fibroids or polyps. Such tests include:

Endometrial biopsy — An endometrial biopsy is often 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. (See "Patient information: Endometrial cancer diagnosis and staging (Beyond the Basics)".)

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 in a healthcare provider's office without anesthesia. Because only a small portion of the endometrium is sampled, the biopsy may miss some causes of bleeding and other tests are sometimes necessary.

Transvaginal ultrasound — An ultrasound uses sound waves to measure an organ's shape and structure. 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. The lining of the uterus is evaluated and measured; postmenopausal women normally have a very thin endometrial lining (usually less than 4 or 5 mm). Ultrasound cannot distinguish between different types of abnormalities (eg, polyp versus cancer) and further testing may be necessary.

Saline infusion sonography ( 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.

Imaging tests — 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. (See "Patient information: Dilation and curettage (D and C) (Beyond the Basics)".)

ABNORMAL UTERINE BLEEDING TREATMENT

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. Nonsteroidal anti-inflammatory drugs (NSAIDS, eg ibuprofen, naproxen sodium) may also be helpful in reducing blood loss and cramping in these women.

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. (See "Patient information: Menorrhagia (excessive menstrual bleeding) (Beyond the Basics)".)

Progesterone — Progesterone is a hormone made by the ovary that is effective in preventing excessive bleeding in women who do not ovulate regularly. A synthetic form of progesterone, called progestin, may be recommended to treat abnormal bleeding. Progestins are usually given as pills (eg, medroxyprogesterone acetate, norethindrone), and are taken once a day for 10 to 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; otherwise, it may not be seen until several days after the last progestin tablet is taken. In some cases, the progestin is given on a regular basis (eg, every few months) to prevent excessive growth of the uterine lining and heavy menstrual bleeding. If no bleeding is seen after progestin treatment, the possibility of an unintended pregnancy should be explored.

Progestins may also be given in other ways, such as in an injection, an implant, or an intrauterine device. These treatments are discussed in detail in a separate topic review. (See "Patient information: Menorrhagia (excessive menstrual bleeding) (Beyond the Basics)".)

Intrauterine device — An intrauterine contraceptive device (IUD) that secretes progestin (eg, 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 (picture 1).

Progestin-releasing IUDs decrease menstrual blood loss by 40 to 50 percent 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. (See "Patient information: Long-term methods of birth control (Beyond the Basics)".)

Surgery — Surgery may be necessary to remove abnormal uterine structures (eg, fibroids, 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. More information about endometrial ablation is available in a separate topic review. (See "Patient information: Menorrhagia (excessive menstrual bleeding) (Beyond the Basics)".)

Women with fibroids can have surgical treatment of their fibroids, either by removing the fibroid(s) (eg, myomectomy) or by reducing the blood supply of the fibroids (eg, uterine artery embolization). More information about these treatments is available separately. (See "Patient information: Uterine fibroids (Beyond the Basics)".)

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Uterine cancer (The Basics)
Patient information: Dilation and curettage (D and C) (The Basics)
Patient information: Endometrial ablation (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Hormonal methods of birth control (Beyond the Basics)
Patient information: Absent or irregular periods (Beyond the Basics)
Patient information: Uterine fibroids (Beyond the Basics)
Patient information: Menorrhagia (excessive menstrual bleeding) (Beyond the Basics)
Patient information: Endometrial cancer diagnosis and staging (Beyond the Basics)
Patient information: Chlamydia (Beyond the Basics)
Patient information: Gonorrhea (Beyond the Basics)
Patient information: Cervical cancer screening (Beyond the Basics)
Patient information: Dilation and curettage (D and C) (Beyond the Basics)
Patient information: Long-term methods of birth control (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

An overview of endometrial ablation
Chronic menorrhagia or anovulatory uterine bleeding
Clinical features and diagnosis of polycystic ovary syndrome in adolescents
Dilation and curettage
Evaluation of the endometrium for malignant or premalignant disease
Initial approach to the premenopausal woman with abnormal uterine bleeding
Overview of causes of genital tract bleeding in women
Terminology and evaluation of abnormal uterine bleeding in premenopausal women
Postmenopausal uterine bleeding

The following organizations also provide reliable health information.

• National Library of Medicine
  
  (www.nlm.nih.gov/medlineplus/healthtopics.html)
• The American College of Obstetricians and Gynecologists
  
  (http://www.acog.org/)
• The Nemours Foundation
  
  (www.kidshealth.org, search for menstrual)
• The Hormone Foundation
  
  (www.hormone.org)

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