Gynecologic Conditions
Abnormal Uterine Bleeding: Causes, Tests and When to Worry
Abnormal uterine bleeding (AUB) is any bleeding from the uterus that's heavier, longer, more frequent or less predictable than a normal period, or that happens between periods, after sex or after menopause. The usual causes are hormone shifts, fibroids, polyps, pregnancy-related problems, thyroid disease and bleeding disorders. Less often it's precancer or cancer, and a gynecologist can usually sort out which with a few simple tests.
This is one of the most common reasons people book a gynecology visit. Most causes are very treatable. A few kinds of bleeding should never be waited out, and those are flagged clearly below.
What counts as abnormal uterine bleeding?
Start with what's typical. For most adults:
- A cycle lasts about 24 to 38 days, from day one of one period to day one of the next
- Bleeding lasts up to about eight days
- Timing stays fairly steady month to month
Your bleeding may be abnormal if you have:
- Heavy periods that soak through pads or tampons fast, or make you double up
- Periods lasting longer than eight days
- Cycles shorter than 24 days or longer than 38 days
- Unpredictable timing, where you genuinely can't guess when the next one will come
- Bleeding or spotting between periods
- Bleeding after sex
- Any bleeding after menopause
A common worry is "is this heavy, or am I just used to it?" Plenty of people have had heavy periods since their teens and assume that's normal. If you plan your day around bathroom access, bleed through clothes or sheets, or pass clots bigger than a quarter, say so. That's worth evaluating.
What causes abnormal uterine bleeding?
Gynecologists sort causes with a memory aid called PALM-COEIN. The "PALM" causes are structural, meaning they show up on an ultrasound or biopsy. The "COEIN" causes don't.
| Letter | Cause | In plain terms |
|---|---|---|
| P | Polyps | Small growths of the uterine lining |
| A | Adenomyosis | Lining tissue growing into the uterine muscle |
| L | Leiomyoma (fibroids) | Benign muscle growths |
| M | Malignancy and hyperplasia | Cancer or precancerous thickening of the lining |
| C | Coagulopathy | Bleeding disorders such as von Willebrand disease, or blood thinners |
| O | Ovulatory dysfunction | Irregular ovulation from PCOS, thyroid disease, perimenopause and more |
| E | Endometrial | Problems with the lining itself, such as inflammation |
| I | Iatrogenic | Caused by a medicine or device, such as birth control or blood thinners |
| N | Not yet classified | Other, less common causes |
Pregnancy, including miscarriage and ectopic pregnancy, gets ruled out first, every time. Yes, even if you're sure you're not pregnant. Infections such as chlamydia can also cause bleeding after sex or between periods.
Which causes are most likely at your age?
- Teens: Irregular ovulation is normal for the first few years after periods start. Very heavy periods from the very first one can point to a bleeding disorder.
- 20s and 30s: Pregnancy-related bleeding, hormonal birth control, infections, polyps, fibroids and PCOS top the list.
- 40s and perimenopause: Irregular ovulation, fibroids, polyps and adenomyosis become more common, and the risk of endometrial hyperplasia rises.
- After menopause: Thinning of the vaginal or uterine lining is a frequent cause, but endometrial cancer has to be ruled out.
What the workup actually feels like
Your clinician will ask about your bleeding pattern, medicines, sexual history and any family history of bleeding problems (nosebleeds, heavy bleeding after dental work or surgery). Then, depending on your age and story, you may have some of these.
Quick and easy
- Pregnancy test: urine or blood, results in minutes
- Complete blood count: one tube of blood to check for anemia
- Thyroid and other hormone tests, as needed
- STI screening: usually a urine sample or a quick vaginal swab
- Pap test, if you're due
Bleeding disorder testing, especially if heavy periods started with your very first one. This is blood work, sometimes several tubes.
Imaging and procedures
- Transvaginal ultrasound: a slim probe goes into the vagina. It feels like pressure more than pain and usually takes 10 to 15 minutes. It's the main way to spot fibroids, polyps or a thickened lining.
- Saline infusion sonohysterography: sterile fluid goes into the uterus through a thin tube during an ultrasound, so the inside of the cavity is outlined. Expect period-like cramping for a few minutes.
- Hysteroscopy: a thin camera looks directly inside the uterus. Some offices do this in the exam room; others schedule it as a short procedure.
- Endometrial biopsy: a thin, flexible tube takes a sample of the lining. The sampling itself is quick, and most people describe a strong cramp. Ask whether you can take an over-the-counter pain reliever beforehand.
ACOG recommends an endometrial biopsy for people 45 and older with abnormal bleeding, and for younger people with risk factors for endometrial cancer, such as obesity, PCOS or bleeding that hasn't responded to treatment. Biopsy results commonly come back in about a week; ask the office how they'll reach you.
How is abnormal uterine bleeding treated?
Treatment depends on the cause, your age and whether you want a pregnancy in the future.
- Hormonal options: birth control pills, patch or ring, progestins, or a hormonal IUD
- Non-hormonal medicines: NSAIDs and tranexamic acid to cut heavy flow
- Treating the root cause: thyroid medicine, PCOS management, or adjusting a medicine that's causing bleeding
- Procedures: hysteroscopic removal of polyps or fibroids, endometrial ablation for people finished with childbearing, or hysterectomy when other options haven't worked
If heavy flow is your main problem, our guide to heavy menstrual bleeding goes deeper. For bleeding caused by fibroids, see uterine fibroids.
Your bleeding log: what to track before the visit
The single most useful thing you can bring is a record. Two or three cycles is ideal, but even one helps. Write down:
- First and last day of each period
- Any spotting between periods, and whether it followed sex
- How heavy: how often you change pads, tampons or cups, whether you double up, and whether you wake at night to change
- Clots, and roughly how big (pea, grape, quarter)
- Pain or cramping, and whether it keeps you home from work or school
- Other symptoms: fatigue, hot flashes, acne, new hair growth
- Every medicine and supplement, including birth control, blood thinners and herbal products
A period-tracking app works, and so does a note on your phone. Have it open when you walk in, because the first question will be "when was your last period?"
When to see a doctor
Make an appointment with a gynecologist if you have:
- Bleeding between periods or after sex
- Periods coming more often than every 24 days or less often than every 38 days
- Periods lasting more than eight days
- A sudden change in your usual pattern
- Signs of anemia: fatigue, shortness of breath, dizziness, or getting winded on the subway stairs
- Any bleeding after menopause, which should be checked promptly
Go to the emergency room if you soak through a pad or tampon every hour for two or more hours, feel faint or lightheaded, or have bleeding with severe pain, especially if you could be pregnant.
Finding a gynecologist in New York
A general gynecologist or OB/GYN can evaluate and treat most causes of abnormal bleeding, often with one office visit and an ultrasound. When you book, ask whether the practice does ultrasounds and biopsies on site; it can save you a second trip across town. Browse gynecologists in Manhattan or Brooklyn, or use our provider search to find someone near you across New York City, Long Island and the Hudson Valley.
Frequently asked questions
Is spotting between periods normal?
Light spotting can happen around ovulation or in the first few months on hormonal birth control. Spotting that keeps happening, follows sex or shows up after menopause should be checked by a clinician.
What is a normal menstrual cycle?
For most adults, a cycle is about 24 to 38 days long, counted from the first day of one period to the first day of the next, with bleeding that lasts up to about eight days. A few days of variation month to month is normal.
Is bleeding after menopause serious?
Any bleeding after menopause, even a single spot, is not normal and should be evaluated soon. It is usually caused by something benign, but it can be an early sign of endometrial cancer.
Can stress cause abnormal bleeding?
Yes, stress can throw off ovulation and cause irregular or missed periods. It shouldn't be blamed until other causes, like pregnancy, thyroid problems and polyps, have been ruled out.
Sources
- ACOG — Abnormal Uterine Bleeding (Patient FAQ)
- ACOG — Diagnosis of Abnormal Uterine Bleeding in Reproductive-Aged Women (Practice Bulletin 128)
- FIGO — Classification system (PALM-COEIN) for causes of abnormal uterine bleeding
- MedlinePlus — Vaginal bleeding
This article is for general education and is not medical advice. It does not replace an evaluation by a licensed clinician who knows your history. If you think you have a medical emergency, call 911.