Abnormal Vaginal Bleeding: Causes and When to Worry

What counts as abnormal vaginal bleeding

A normal menstrual cycle is 24 to 38 days long, with bleeding lasting up to 8 days and cycle length varying by no more than about 7 to 9 days month to month. Bleeding is considered abnormal when:

• periods come more often than every 24 days (frequent menstruation)
• periods are more than 38 days apart or unpredictable
• bleeding lasts longer than 8 days (long menstrual periods)
• bleeding is heavy enough to soak a pad or tampon every 1 to 2 hours, pass clots larger than a quarter, or interfere with daily life (heavy menstrual bleeding)
• bleeding or spotting happens between periods or after sex
• any bleeding occurs during pregnancy or after menopause

Doctors call bleeding from the uterus outside these patterns abnormal uterine bleeding (AUB). Bleeding can also come from the cervix, vagina or vulva, or from the bladder or rectum and be mistaken for vaginal bleeding.

Causes: the PALM-COEIN system

Gynecologists use the FIGO PALM-COEIN system to sort causes. PALM causes are structural and can be seen on scans. COEIN causes are not.

Causes by life stage

Teenagers

In the first 2 to 3 years after periods start, cycles often skip ovulation and are irregular. Very heavy periods from the start can signal a bleeding disorder such as von Willebrand disease, which is found in roughly 5 to 20 percent of people with heavy periods in studies. Always consider pregnancy and sexually transmitted infections.

Reproductive years

• Pregnancy-related bleeding: implantation spotting, miscarriage, and ectopic pregnancy. Take a pregnancy test first.
• Hormonal contraception: breakthrough bleeding is common in the first months, with missed pills, or with progestin-only methods.
• Ovulation problems: polycystic ovary syndrome, thyroid disease, high prolactin, weight change, intense exercise and stress.
• Structural causes: uterine fibroids, endometrial polyps, adenomyosis and cervical polyps.
• Infections: chlamydia, gonorrhea and pelvic inflammatory disease cause spotting, bleeding after sex, discharge and pain. Cervicitis makes the cervix bleed easily.
• Cervical changes: a cervical ectropion (harmless), or precancer and cancer of the cervix, can cause bleeding after sex.

Perimenopause

In the years before menopause, ovulation becomes irregular, so periods may come closer together, further apart, or be much heavier. This is common, but persistent irregular or heavy bleeding over age 45 needs evaluation to rule out endometrial hyperplasia or cancer.

After menopause

Any bleeding 12 months or more after your last period is abnormal. Most often it is from thinning of the vaginal lining (atrophy), polyps or hormone therapy. But about 1 in 10 people with postmenopausal bleeding has endometrial cancer, so it always needs prompt assessment. See vaginal bleeding after menopause.

Symptoms that come with it

• Pelvic pain and fever: infection or pelvic inflammatory disease.
• Severe one-sided pain with a missed period: ectopic pregnancy.
• Tiredness, breathlessness, pale skin: iron deficiency anemia from blood loss.
• Acne, excess hair, irregular cycles: PCOS.
• Weight change, feeling hot or cold, hair changes: thyroid disease.
• Easy bruising, nosebleeds, bleeding gums: a bleeding disorder.

How doctors find the cause

A doctor will ask about your cycle pattern (a period-tracking app helps), how heavy bleeding is, contraception, sexual history, pregnancy possibility, medicines and family history of bleeding problems. Tests often include:

1. Pregnancy test, always first in anyone who could be pregnant.
2. Pelvic exam and cervical screening if due, plus swabs for infection.
3. Blood tests: complete blood count and ferritin for anemia; thyroid function; prolactin; clotting tests and von Willebrand studies when bleeding has been heavy since the start.
4. Transvaginal ultrasound for fibroids, polyps, adenomyosis and endometrial thickness.
5. Endometrial biopsy: recommended for people over 45 with abnormal bleeding, younger people with risk factors such as obesity or PCOS, or bleeding that does not respond to treatment.
6. Hysteroscopy: a camera inside the uterus to see and remove polyps or fibroids.

Treatment

Treatment depends on the cause, your age and whether you want to become pregnant.

Medicines

• Levonorgestrel IUD: the most effective medical treatment for heavy bleeding, reducing blood loss by about 70 to 90 percent for many users.
• Combined hormonal contraception or progestins: regulate cycles and reduce bleeding.
• Tranexamic acid: a non-hormonal tablet taken only during heavy days.
• NSAIDs such as ibuprofen or naproxen during the period reduce flow by about a quarter to a third and ease cramps. Follow the label dose.
• Iron supplements for anemia.
• Treating the cause: thyroid medicine, antibiotics for infection, PCOS management.

Procedures

• Polyp removal by hysteroscopy.
• Fibroid treatments: myomectomy, uterine artery embolization or newer medicines.
• Endometrial ablation: destroys the uterine lining in people who do not want future pregnancy.
• Hysterectomy: a definitive option when other treatments fail.

Frequently asked questions

What is considered abnormal vaginal bleeding?

Abnormal bleeding includes periods more often than every 24 days or more than 38 days apart, bleeding longer than 8 days, very heavy flow, bleeding between periods or after sex, any bleeding in pregnancy, and any bleeding after menopause.

When should I worry about abnormal vaginal bleeding?

Seek emergency care for soaking a pad every hour for 2 hours, fainting, or bleeding with severe pain in possible pregnancy. See a doctor soon for any bleeding after menopause, during pregnancy, after sex, or irregular bleeding lasting more than 2 or 3 cycles.

Can stress cause abnormal vaginal bleeding?

Yes. Significant stress, intense exercise, illness and rapid weight change can disrupt ovulation, causing late, missed, irregular or spotting periods. Persistent changes should still be checked, since stress is a diagnosis made after other causes are excluded.

Is bleeding between periods a sign of cancer?

Usually not. Most bleeding between periods comes from hormonal contraception, ovulation spotting, polyps, infections or cervical ectropion. But cervical and endometrial cancers can cause it, especially after sex or over age 45, so persistent bleeding needs evaluation.

Why am I spotting on birth control?

Breakthrough spotting is common in the first 3 to 6 months of a new pill, patch, ring, implant or hormonal IUD, and with missed or late pills. Persistent spotting after that, or with pain or discharge, needs a check for infection or other causes.

What tests are done for abnormal uterine bleeding?

Typical tests are a pregnancy test, blood count and iron levels, thyroid function, sexually transmitted infection swabs, and a transvaginal ultrasound. An endometrial biopsy is added for people over 45 or with risk factors, and hysteroscopy if polyps or fibroids are suspected.