Abnormal uterine bleeding (AUB) is bleeding from the uterus that is longer than usual or that occurs at an irregular time. Bleeding may be heavier or lighter than usual and occur often or randomly.

AUB can occur:

• As spotting or bleeding between your periods
• After sex
• For more days than your normal period
• Heavier than normal
• After menopause

It does not occur during pregnancy. Bleeding during pregnancy has different causes. If you have any bleeding when you are pregnant, be sure to contact your health care provider.

Anovulatory bleeding; Abnormal uterine bleeding - hormonal; Polymenorrhea - dysfunctional uterine bleeding

Every woman's menstrual cycle is different.

• On average, a woman's period (menstrual flow) occurs every 28 days, although cycles may vary from 24 to 34 days.
• Menstruation flow normally last about 4 to 7 days.
• Young girls may get their periods anywhere from 21 to 45 days or more apart.
• Women in their 40s may start to have their period less often or have the interval between their periods decrease.

For most women, female hormone levels change every month. The hormones estrogen and progesterone are released as part of the process of ovulation. When a woman ovulates, an egg is released.

AUB can occur when the ovaries do not release an egg. Changes in hormone levels cause your period to be later or earlier. Your period may sometimes be heavier than normal.

AUB is more common in teenagers or in premenopausal women. Women who are overweight also may be more likely to have AUB.

In many women, AUB is caused by a hormone imbalance. It can also occur due to following causes:

• Thickening of the uterine wall or lining
• Uterine fibroids
• Uterine polyps
• Cancers of ovaries, uterus, cervix, or vagina
• Bleeding disorders or problems with blood clotting
• Polycystic ovary syndrome
• Severe weight loss
• Hormonal birth control, such as birth control pills or intrauterine devices (IUD)
• Excessive weight gain or loss (more than 10 pounds or 4.5 kilograms)
• Infection of the uterus or cervix

AUB is unpredictable. The bleeding may be very heavy or light, and can occur often or randomly.

Symptoms of AUB may include:

• Bleeding or spotting from the vagina between periods
• Periods that occur less than 28 days apart (more common) or more than 35 days apart
• Time between periods changes each month
• Heavier bleeding (such as passing large clots, needing to change protection during the night, soaking through a sanitary pad or tampon every hour for 2 to 3 hours in a row)
• Bleeding that lasts for more days than normal or for more than 7 days

Other symptoms caused by changes in hormone levels may include:

• Excessive growth of body hair in a male pattern (hirsutism)
• Hot flashes
• Mood swings
• Tenderness and dryness of the vagina

A woman may feel tired or fatigued if she loses too much blood over time. This is a symptom of anemia.

Your provider will rule out other possible causes of irregular bleeding. You will likely have a pelvic exam and Pap/HPV test. Other tests that may be done include:

• Complete blood count (CBC)
• Blood clotting profile
• Liver function tests (LFT)
• Fasting blood glucose
• Hormone tests, for FSH, LH, male hormone (androgen) levels, prolactin, and progesterone
• Pregnancy test
• Thyroid function tests

Your provider may recommend the following:

• Culture to look for infection
• Biopsy to check for precancer, cancer, or to help decide on hormone treatment
• Hysteroscopy, performed in your provider's office to look into the uterus through the vagina
• Ultrasound to look for problems in the uterus or pelvis
• Saline infusion sonohysterogram to further evaluate the uterine cavity for a source of the bleeding

Treatment may include one or more of the following:

• Low-dose birth control pills
• Hormone therapy
• High-dose estrogen therapy for women with very heavy bleeding
• Intrauterine device (IUD) that releases the hormone progestin
• Nonsteroidal anti-inflammatory drugs (NSAIDs) taken just before the period starts
• Tranexamic acid is a prescription medicine that treats heavy menstrual bleeding. It comes in a tablet and is taken each month at the start of the menstrual period.
• Surgery, if the cause of the bleeding is a polyp or fibroid

Your provider may put you on iron supplements if you have anemia.

If you want to get pregnant, you may be given medicine to stimulate ovulation.

Women with severe symptoms that don't improve or who have a cancerous or precancerous diagnosis may require other procedures such as:

• Surgical procedure to destroy or remove the lining of the uterus
• Hysterectomy to remove the uterus

Hormone therapy often relieves symptoms. Treatment may not be needed if you do not develop anemia due to blood loss. A treatment focused on the cause of the bleeding is often immediately effective. That is why it's important to understand the cause.

Complications that may occur:

• Infertility (inability to get pregnant)
• Severe anemia due to a lot of blood loss over time
• Increased risk for endometrial cancer

Contact your provider if you have unusual vaginal bleeding.

The American College of Obstetricians and Gynecologists website. ACOG committee opinion no. 557: Management of acute abnormal uterine bleeding in nonpregnant reproductive-aged women. Reaffirmed 2020. www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2013/04/management-of-acute-abnormal-uterine-bleeding-in-nonpregnant-reproductive-aged-women. Accessed December 15, 2022.

Bahamondes L, Ali M. Recent advances in managing and understanding menstrual disorders. F1000Prime Rep. 2015;7:33. PMID: 25926984 pubmed.ncbi.nlm.nih.gov/25926984/.

Ryntz T, Lobo RA. Abnormal uterine bleeding: etiology and management of acute and chronic excessive bleeding. In: Gershenson DM, Lentz GM, Valea FA, Lobo RA, eds. Comprehensive Gynecology. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 26.

Schrager S. Abnormal uterine bleeding. In: Kellerman RD, Rakel DP, Heidelbaugh JJ, Lee EM, eds. Conn's Current Therapy 2023. Philadelphia, PA: Elsevier; 2023:1197-1198.