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    When Should You Go to the Hospital for Heavy Menstrual Bleeding?

    Published 07 April 2021
    Fact Checked
    Reviewed by Irina Ilyich, Flo lead medical advisor, Lithuania
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    For most people, having a slightly heavier period for a few days is entirely normal. But if you experience a sudden, heavy period or one that lasts longer than expected, you may need to seek medical care.

    Is every heavy flow considered to be HMB?

    Heavy menstrual bleeding (HMB) is also known as menorrhagia. This medical term refers to abnormally heavy or prolonged bleeding. Although it’s quite difficult to estimate the incidence of HMB, it’s somewhere in the range of 5 to 30 percent, according to different sources.

    It can be challenging to maintain your normal daily activities with HMB because of significant blood loss. And some bleeding can be very heavy, leading to the need to change your tampon or pad frequently (less than two hours). If you think your periods are like this, talk with your health care provider about possible treatment options.

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    Various things can cause heavy menstrual bleeding. Here are some of the causes:

    • Fibroids and polyps: Uterine fibroids and uterine polyps may cause increased bleeding and irregular periods.
    • Adenomyosis: This causes endometrial tissue (lining of the uterus) to grow into the uterine wall. It’s seen in later childbearing years and usually resolves following menopause.
    • Endometriosis: This condition causes endometrial-like tissue to grow outside of the uterus. This growth usually occurs on the ovaries and supporting ligaments of the uterus and in the pelvic cavity.
    • Irregular ovulation: When ovulation and periods don’t occur regularly, areas of the endometrium (the uterine lining) can become too thick. This irregularity usually happens during puberty, perimenopause, and in people diagnosed with polycystic ovary syndrome and hypothyroidism.
    • Bleeding disorders: Some disorders prevent blood from clotting properly, which causes heavy bleeding.
    • Medications: Blood thinners can cause heavy menstrual bleeding.
    • Intrauterine devices (IUD): IUDs, particularly those containing copper, may also cause heavier menstrual bleeding, especially during the first year following insertion.
    • Cancer: Heavy menstrual bleeding can be an early sign of uterine or cervical cancer. Most cases happen in people in their mid-60s who are postmenopausal. With early diagnosis, treatment is highly effective.
    • Other causes: Heavy bleeding can be pregnancy-related, in the event of ectopic pregnancy or miscarriage. Pelvic inflammatory disease also can cause heavy menstrual bleeding. Other times, the cause is unknown.

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    What’s normal and what’s not: When to seek medical attention for HMB

    Determining if you have heavy menstrual bleeding (as defined medically) can be tricky, because many women may have a different idea of what heavy bleeding actually is. Typically, menstrual bleeding lasts about four to five days, and overall blood loss is minimal (two to three tablespoons). It’s worth noting that menstruation isn’t just blood. It also contains endometrial tissue, so it’s not always easy to estimate actual blood loss. 

    According to the American College of Obstetrics and Gynecology (ACOG), any of the following are signs of heavy menstrual bleeding:

    • Bleeding that occurs for more than seven days
    • Needing to use a tampon and a pad simultaneously or using more than one pad to prevent leaking
    • Vaginal bleeding that’s heavy enough to soak at least one pad or tampon each hour for more than two hours straight
    • Needing to get up in the middle of the night to change pads or tampons 
    • A menstrual flow that includes blood clots that are the size of a quarter or larger
    • Irregular vaginal bleeding or bleeding between periods (that isn’t ovulation spotting)