Abnormal uterine bleeding (AUB) is any menstrual bleeding that differs from a normal period in timing, duration, or amount. It affects 10% to 30% of women of reproductive age and includes periods that last longer than seven days, bleeding between periods, cycles shorter than 24 days or longer than 38 days, and bleeding that soaks through a pad or tampon every hour for several consecutive hours. A typical period lasts four to five days and produces about two to three tablespoons of blood. Bleeding that doubles that amount or stretches well beyond a week crosses into abnormal territory.
Common Causes by Age Group
The causes of abnormal uterine bleeding fall into two broad categories: structural problems in the uterus and non-structural issues related to hormones, blood clotting, or medications. Doctors use an acronym called PALM-COEIN to organize these causes systematically. The PALM side covers structural causes: polyps, adenomyosis, leiomyomas (fibroids), and malignancy or precancerous changes. The COEIN side covers non-structural causes: coagulopathy (bleeding disorders), ovulatory dysfunction, endometrial disorders, iatrogenic causes (from medications or devices), and a catch-all “not yet classified” category.
Which causes are most likely depends heavily on your age. Teenagers and women approaching menopause are far more likely to have ovulatory dysfunction, where the body doesn’t release an egg regularly and hormone levels become unpredictable. Structural problems like fibroids and polyps become more common with age, and the risk of precancerous or cancerous changes in the uterine lining also rises over time.
Ovulatory Dysfunction and Hormonal Imbalance
Ovulatory dysfunction is one of the most frequent causes of abnormal bleeding. When ovulation doesn’t happen, the ovary doesn’t form the structure that normally produces progesterone. Without progesterone to balance it, estrogen keeps stimulating the uterine lining to grow thicker and thicker. Eventually that lining outgrows its blood supply and sheds unevenly, producing bleeding that can be unpredictable, prolonged, and sometimes heavy. You might go weeks or months without a period, then bleed for days or weeks when it finally comes.
Several things can disrupt ovulation. Significant physical or emotional stress, poor nutrition, and rapid weight changes all affect the hormonal signals that trigger egg release. In women carrying excess weight, fat tissue converts certain hormones into estrogen, which can suppress the brain signals needed for ovulation. Insulin resistance plays a role too: high insulin levels can interfere with the ovary’s ability to release an egg, which is part of why conditions like polycystic ovary syndrome so often cause irregular bleeding. Even in cycles where ovulation does occur, a shortened first half of the cycle or inadequate progesterone production in the second half can produce spotting or irregular bleeding.
Bleeding Disorders in Adolescents
Heavy periods in teenagers deserve special attention because an underlying bleeding disorder is surprisingly common in this group. In one study of 113 adolescents with abnormal uterine bleeding, nearly 48% had some form of hemostatic disorder, meaning their blood didn’t clot normally. Platelet dysfunction was the most common finding at about 18%, followed by von Willebrand disease at 13% and clotting factor deficiencies at 12%. These are inherited conditions that may not become apparent until a young woman starts menstruating. If a teenager has heavy periods from the very beginning, especially combined with easy bruising, frequent nosebleeds, or a family history of bleeding problems, testing for clotting disorders is important.
How AUB Is Diagnosed
Diagnosis starts with a detailed history of your bleeding pattern: how long your periods last, how heavy they are, whether bleeding happens between periods, and how your cycles have changed over time. Blood tests typically check for anemia, thyroid problems, hormone levels, and sometimes clotting disorders.
Imaging plays a key role in identifying structural causes. A standard transvaginal ultrasound is usually the first step, but it catches only about 56% of abnormalities inside the uterine cavity. Saline infusion sonography, where a small amount of sterile fluid is placed inside the uterus before scanning, improves detection significantly, picking up about 81% of abnormalities with essentially no false positives. This makes it particularly useful for spotting polyps and fibroids that bulge into the uterine cavity.
For women with risk factors for precancerous changes, such as long-standing irregular cycles, obesity, or age over 45, an endometrial biopsy is often recommended. This involves taking a small tissue sample from the uterine lining to examine under a microscope. It can be done in a regular office visit and takes only a few minutes, though it causes cramping similar to a strong menstrual cramp.
Hormonal Treatment Options
For many women, hormonal treatments are the first line of management. The most effective option for heavy menstrual bleeding is the hormonal IUD that releases a small amount of progestin directly into the uterus. Clinical trials show it reduces blood loss by about 93% within three cycles and roughly 98% by six cycles. Many women’s periods become extremely light or stop altogether. Beyond reducing bleeding, it also provides contraception and lasts several years.
Combined hormonal contraceptives (pills, patches, or rings) regulate cycles and reduce bleeding by thinning the uterine lining. Progestin-only pills or injections work similarly. The right choice depends on your specific situation, whether you want contraception, your risk factors for blood clots, and how your body responds to hormones.
Non-Hormonal and Surgical Options
For women who prefer to avoid hormones or can’t use them, a medication that helps blood clot more effectively can reduce menstrual blood loss. It’s taken as tablets three times daily, only during the days of heavy bleeding, for a maximum of five consecutive days per cycle. It works by preventing the normal breakdown of blood clots in the uterine lining, so less blood is lost.
When medications don’t provide enough relief, surgical options come into play. Endometrial ablation destroys the uterine lining to reduce or stop bleeding. It’s a less invasive procedure than hysterectomy, with a faster recovery, typically days rather than weeks. However, about 25% of women who undergo ablation need additional gynecological surgery afterward, and roughly 20% eventually require a hysterectomy because the bleeding returns or new symptoms develop. Ablation also isn’t appropriate for women who want to become pregnant in the future.
Hysterectomy, the removal of the uterus, is the only treatment that permanently and definitively ends abnormal uterine bleeding. It’s generally reserved for women who haven’t responded to other treatments, who have large fibroids or other structural problems, or who have completed childbearing and want a permanent solution. Recovery takes several weeks depending on the surgical approach.
When Bleeding Patterns Change
Any new change in your bleeding pattern is worth tracking. Periods that have gradually gotten heavier over months or years often point to a slowly growing fibroid or developing adenomyosis. Bleeding that starts after months of no periods, particularly in women over 45, raises more concern about endometrial changes that need evaluation. Bleeding after menopause, even light spotting, is always considered abnormal and should be evaluated promptly.
Keeping a simple record of your cycle length, days of bleeding, and heaviness (light, moderate, or heavy) gives your healthcare provider much more useful information than trying to recall patterns from memory. Several period-tracking apps make this easy, and the data can help distinguish between occasional variation and a pattern that needs investigation.