Abnormal Uterine Bleeding (AUB)

What counts as abnormal uterine bleeding

A normal menstrual cycle has bleeding every 24 to 38 days, for up to 8 days, at a volume that does not interfere with daily life. AUB covers any departure from this:

Older terms such as menorrhagia (heavy periods) and metrorrhagia (irregular bleeding) are being replaced by these plain descriptions.

Causes: the PALM-COEIN system

The International Federation of Gynecology and Obstetrics (FIGO) groups causes into structural ones you can see on imaging or biopsy (PALM) and non-structural ones (COEIN). More than one cause is often present.

Structural causes (PALM)

• Polyps: endometrial polyps are soft growths of the womb lining, a common cause of bleeding between periods.
• Adenomyosis: womb lining growing into the muscle wall, causing heavy, painful periods and an enlarged, tender uterus.
• Leiomyoma: fibroids are benign muscle tumors. Those bulging into the cavity (submucosal) cause the heaviest bleeding.
• Malignancy and hyperplasia: endometrial cancer and endometrial hyperplasia, a thickened lining that can become cancer. Most important after age 45 and after menopause.

Non-structural causes (COEIN)

• Coagulopathy: bleeding disorders, most often von Willebrand disease, which affects up to 1 in 5 women with heavy periods since their teens. Blood thinners count here too.
• Ovulatory dysfunction: irregular or absent ovulation from PCOS, the teen years, perimenopause, thyroid disease, high prolactin, stress or weight change.
• Endometrial: a womb lining that bleeds more because of local factors, even with regular cycles.
• Iatrogenic: caused by medical treatment, such as hormonal contraception, IUDs, blood thinners and some antidepressants. See IUD-related bleeding.
• Not yet classified: rarer causes such as arteriovenous malformations and a scar defect from a previous cesarean (niche).

Pregnancy-related bleeding (miscarriage, ectopic pregnancy) is excluded first, because it needs different management.

Symptoms

• periods that are heavier, longer, more frequent or less predictable than before
• passing clots larger than a quarter
• needing to change pads or tampons every 1 to 2 hours, or using double protection
• bleeding through clothes or bedding
• bleeding between periods or after sex
• tiredness, breathlessness, dizziness, hair loss or pale skin from iron deficiency anemia
• pelvic pain or pressure with fibroids or adenomyosis

Diagnosis

1. History: cycle pattern, how heavy, how long it has been happening, contraception, medicines, family history of bleeding disorders, and symptoms of thyroid or hormonal problems.
2. Pregnancy test.
3. Pelvic exam including the cervix.
4. Blood tests: complete blood count and ferritin for anemia, thyroid function, and tests for bleeding disorders if heavy bleeding started at the first period or there is easy bruising or other bleeding.
5. Transvaginal ultrasound to look for fibroids, polyps, adenomyosis and lining thickness.
6. Endometrial biopsy: recommended for people 45 or older with AUB, and for younger people with risk factors (obesity, PCOS, long-standing unopposed estrogen, failed treatment, or Lynch syndrome).
7. Saline infusion sonography or hysteroscopy: a closer look inside the uterus to find and remove polyps or submucosal fibroids.

Treatment

Treatment depends on the cause, how heavy the bleeding is, age, and whether you want to become pregnant.

Medicines

• Tranexamic acid: taken only during heavy days, reduces blood loss by about a third to a half. Not hormonal.
• NSAIDs such as ibuprofen or naproxen during periods: reduce bleeding and cramps.
• Levonorgestrel IUD (hormonal IUD): one of the most effective treatments for heavy bleeding, reducing blood loss dramatically for up to 5 years or more.
• Combined birth control pills, patch or ring: regulate cycles and lighten periods.
• Progestogens taken cyclically or continuously.
• GnRH antagonists (such as relugolix or elagolix combinations) for fibroid-related bleeding.
• Iron supplements for anemia.

Procedures and surgery

• Hysteroscopic removal of polyps and submucosal fibroids
• Endometrial ablation: destroys the womb lining to reduce bleeding. Only for those who have completed childbearing.
• Uterine artery embolization or myomectomy for fibroids
• Hysterectomy: permanent cure, considered when other treatments have failed or are not suitable

Acute heavy bleeding

Very heavy bleeding is treated urgently with high-dose hormones, tranexamic acid, IV fluids and sometimes blood transfusion or a procedure.

Complications

• iron deficiency anemia, which can cause fatigue and reduced quality of life
• missed school or work
• a delay in diagnosing endometrial cancer if postmenopausal or persistent bleeding is not investigated

Frequently asked questions

What is abnormal uterine bleeding?

Abnormal uterine bleeding is any bleeding from the uterus that is too heavy, too long, too frequent, irregular, between periods, after sex or after menopause. It is common and has many causes, from hormonal changes and fibroids to bleeding disorders and, less often, cancer.

What is the most common cause of abnormal uterine bleeding?

In teenagers and women approaching menopause, irregular ovulation is the most common cause. In women in their 30s and 40s, fibroids, polyps and adenomyosis are frequent. After menopause, thinning of the lining (atrophy) is common, but cancer must be ruled out.

What does PALM-COEIN stand for?

It is a system for classifying causes of abnormal uterine bleeding. PALM stands for polyp, adenomyosis, leiomyoma (fibroid) and malignancy or hyperplasia. COEIN stands for coagulopathy, ovulatory dysfunction, endometrial, iatrogenic and not yet classified.

How is abnormal uterine bleeding treated?

Options include tranexamic acid, NSAIDs, a hormonal IUD, birth control pills and progestogens. Polyps and some fibroids can be removed in a minor procedure. Endometrial ablation, embolization and hysterectomy are options when medicines do not work.

Is abnormal uterine bleeding a sign of cancer?

Usually not, but it can be, especially after menopause or over age 45. Any bleeding after menopause and persistent irregular bleeding in older women need an ultrasound and often an endometrial biopsy to rule out cancer.