Abnormal Uterine Bleeding, Explained
Bleeding that's heavier, longer, more frequent, or less predictable than a typical cycle has a name — abnormal uterine bleeding, or AUB — and a real, structured workup behind it. It's not something to just get used to.
Last updated August 2026
What counts as abnormal
A typical cycle runs 21–35 days with bleeding lasting 2–7 days. Worth a conversation: periods lasting more than 7 days, cycles shorter than 21 or longer than 35 days, bleeding between periods, soaking through a pad or tampon within an hour for several hours in a row, or any bleeding after menopause.
How providers think about the cause
Clinicians use a classification system called PALM-COEIN to sort the possible cause into two buckets. Structural causes (PALM: Polyp, Adenomyosis, Leiomyoma/fibroids, Malignancy & hyperplasia) are something physically there. Non-structural causes (COEIN: Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not yet classified) are more about how the system is functioning than something you could see or feel. Figuring out which bucket — or which specific letter — you're in shapes the whole workup.
How it's evaluated
A typical workup includes a detailed history and exam, often a pelvic ultrasound, and sometimes labs — checking your thyroid, clotting function, and whether the bleeding has caused anemia. If you're bleeding after menopause, or have ongoing irregular bleeding at a higher-risk age, a biopsy of the uterine lining is often part of ruling out more serious causes.
When to seek care promptly
Soaking through protection every hour for two or more hours straight, any bleeding after menopause, or symptoms of significant anemia — dizziness, rapid heartbeat, extreme fatigue — are reasons to reach out promptly rather than wait it out.
Worth discussing with your provider
Educational information only — general patterns that vary by person. This is not medical advice, a diagnosis, or a substitute for care from your own clinician.
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