Period Blood Clots: What Causes Blood Clots During Period?

Do you have period blood clots that are dark colored? Are you feeling weak because of your prolonged periods? Do you have blood clots during periods for more than 24 hours? Do you change your sanitary pad frequently more than normal?

This article will explain what’s normal about the blood clots you see during your period and when it’s abnormal.

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What causes period (Menstruation)?

Period, experienced by women, is due to breakdown of the endometrium covering your womb. It is usually due to hormonal changes that occur during your menstrual cycle.

How long do period last?
Normal period may last between 2 — 7 days and may get lighter as it ends.

Doctors call very heavy or very long periods heavy menstrual bleeding or menorrhagia. You may have heavy menstrual bleeding if your period lasts more than 7 days, you pass large clots, or you soak pads or tampons very quickly.

What causes period to come out?
Your period cycle (menstrual cycle) is the difference between 2 periods. The first period day is the first day of your menstrual cycle. During your period, FSH (follicle stimulating hormone) will stimulate your ovaries to start follicle development. As these follicles grow, they produce estrogen.

What does estrogen do?
After day 7 of your period, there is a thin layer of endometrium covering your womb. Estrogen will cause proliferation of endometrial cells to build up your endometrium should you get pregnant.

Also, rising estrogen level will stimulate the pituitary gland to cause LH surge. LH surge occurs about 12 — 36 hours before your ovulation. After ovulation, estrogen level decreases with an increase in progesterone hormone.

What does progesterone hormone do?
Dominant progesterone and estrogen will continue to stimulate the endometrial glands to become more tortuous and prepare for implantation.

After intercourse, if sperm meets the egg during your fertile period and fertilization occurs, the baby (zygote) may be implanted into this endometrium. If implantation occurs, some women may experience slight bleeding or spotting before period is due, but many women do not notice any bleeding at all. Heavy bleeding like a period is not normal implantation bleeding.

If implantation does not occur, the endometrium will break down, forming your period.

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What causes blood clots during period?

These are the reasons you may have period blood clots.

Normal period

Early in your period, there is a rapid breakdown of the endometrium that can come out as clots. This usually does not last for more than 24 to 36 hours. This is because fibrinolysin helps break down clots in your period.

During a heavy menstrual flow, if the endometrium is broken down very fast, fibrinolysin will not have enough time to break clots down. This comes out as blood clots.

If your blood clots are persistent for days with heavy bleeding, if clots are bigger than a coin/quarter, or you are soaking pads or tampons every 1–2 hours, then it is abnormal and you should see your doctor.

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Uterine fibroid

These are growths in the uterus or womb in women that can cause blood clots during period. They commonly occur in women after the age of 30. Cause of fibroid is still not clear, though it is believed that there is a strong familial link. If your mother or your sister were diagnosed with fibroid, then there is a possibility that you may have fibroid. Also, fibroid is common in young women due to estrogen hormone. After menopause or during perimenopause, it often shrinks in women.

There are different types of fibroid. The submucous type is the commonest cause of very severe bleeding in women. It is fibroid growth just beneath the endometrium. Other types of fibroids are the intramural type (fibroid that grows within the uterine muscle), subserous type (grows outside the uterus) and the cervical fibroid.

You can read more here: uterine fibroids – symptoms and causes.

What are the symptoms of fibroid?

• Heavy prolonged periods that are more than 7 days

• Period blood clots

• Frequent changing of your pads or tampons

• Body weakness from anemia

• Huge fibroid can cause abdominal swelling and obstructive symptoms like difficulty in passing urine or stool

Can fibroid be treated?

If you have heavy excessive bleeding with clots, these are some medications that could help (only under your doctor’s prescription and monitoring):

• Mefenamic acid

• Tranexamic acid

• GnRH agonist

Surgical options are:

• Myomectomy (surgical removal of the fibroid)

• Hysterectomy (surgical removal of the uterus)

• Fibroid polyp removal

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Endometrial thickening (hyperplasia)

Endometrial thickening (endometrial hyperplasia) can occur in women due to hormone imbalance. Women with PCOS (polycystic ovarian syndrome) or other conditions that cause high estrogen level without enough progesterone can have proliferation and thickening of the endometrium. This thickened lining can come out as blood clots and be excessive.

You can read patient-friendly information on endometrial hyperplasia.

What are the symptoms of endometrial hyperplasia?

• Prolonged bleeding with blood clots during period

• Short menstrual cycles

• Vaginal bleeding in women that are more than 40 years

• Bleeding after menopause

• Infertility in some women

Who can have endometrial hyperplasia?

Risk is higher in women who:

• Are more than 35–40 years

• Are overweight or obese

• Have PCOS or other causes of not ovulating regularly

• Are nulliparous women (women that have never been pregnant before)

• Use estrogen replacement without progesterone

• Have a family history of endometrial or colon cancer

You will need to inform your doctor and may need a progesterone pill or a hormonal device (like a progesterone intrauterine system) to normalize your period and protect the lining. If you are already taking estrogen replacement, then you will usually need progesterone too.

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Vaginal infections in women

If you have infection down there at your vagina, it may make your period heavier or more irregular and sometimes you may notice small clots with the bleeding. However, blood clots alone are not the main sign of infection.

What are vaginal infection symptoms?

Abnormal discharge like greenish yellowish discharge, yellowish smelly discharge or thick white discharge with odor are symptoms of vaginal infections. Others are vaginal itching, vulva sore, fever, abdominal pain and body weakness.

You should inform your doctor if you have these symptoms. Vaginal discharge samples are collected and tested for the cause. Treatment with antibiotics or antifungals will follow after testing your blood and vaginal discharge with good success rate.

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Endometriosis and Adenomyosis

Adenomyosis and endometriosis in women can cause heavy prolonged bleeding with blood clots.

What is endometriosis?

This is abnormal growth of the endometrium outside the uterus. Endometrial tissues can be found in the ovaries, fallopian tubes, abdomen and other parts of the body.

Symptoms of endometriosis are:

• Severe pelvic pain

• Painful periods or cramping

• Painful sexual intercourse

• Period blood clots

• Sometimes difficulty getting pregnant

Endometriosis can be treated with hormonal contraceptive, pain relief drugs like ibuprofen or naproxen, and sometimes surgery to remove endometriosis spots. There is no simple permanent cure; it is usually a long-term condition that can flare up again.

What is adenomyosis?

This is presence of endometrial tissues growing inside the muscle wall of the uterus (myometrium). If you’ve had an abortion with curettage or delivered by cesarean section, then previous surgery on the uterus may increase the risk of adenomyosis and heavy blood clots during period.

Symptoms of adenomyosis are:

• Severe low abdomen pain

• Heavy menstruation

• Painful periods

• Infertility in some women

• Pain during sexual intercourse

Adenomyosis can be treated with ibuprofen, hormonal IUDs and contraceptives, and other hormone medicines to reduce bleeding and pain. However, the only definite cure is removal of the uterus (hysterectomy), and this is usually reserved for women who have completed childbearing and still have very severe symptoms. You can learn more about adenomyosis.

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Endometrial cancer

If you are above about 40–45 years and having new or worsening period blood clots, very heavy periods, or bleeding between periods, then your doctor will want to rule out endometrial cancer or thickening. Most women with these symptoms do not have cancer, but it is important to check.

Most women that have endometrial cancer complain of abnormal uterine bleeding, such as heavy irregular periods in premenopausal women or any bleeding after menopause. However, some women may experience clear or watery vaginal discharge, painful sexual intercourse, pelvic pain, or discomfort while urinating.

You can read more here: endometrial (uterine) cancer – symptoms and causes.

How can cancer be diagnosed?

If cancer of the endometrium is suspected, your doctor will take samples of uterine tissue for testing. This is endometrial biopsy. Transvaginal ultrasound and hysteroscopy may also be used. If your cancer is still in early stages, it can often be treated and cured.

Always inform your doctor of abnormal bleeding if you are 45 years or older, or if you have any bleeding after 12 months without a period (after menopause).

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I have blood clots on period, how do I stop it?

Most women with blood clots during day 1 or 2 of your period may be normal. However, if your bleeding is more than 7 days and you have large blood clots, feel dizzy or very weak, or are soaking pads or tampons every 1–2 hours, then it is abnormal.

A menstrual cup, tampon, or thicker pads can help collect heavy flow and clots, but they do not treat the underlying cause. You may still leak if the flow is very heavy.

In addition, if your period continues more than 7 days with blood clots, or you are worried, you should let your doctor know. Your doctor may check for anemia, pregnancy, fibroid, endometrial thickening, bleeding disorders or other causes and then prescribe treatment like NSAIDs, tranexamic acid or hormonal tablets or IUDs if needed.

Seek urgent medical care if:

• You soak a pad or tampon every hour for more than 2–3 hours

• You feel dizzy, faint, or have chest pain or shortness of breath

• You are pregnant or your period is very late and you see heavy clots

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FAQs about period blood clots in women

These are some frequently asked questions about blood clots during period. Let us know if you have any questions.

Is it normal to have blood clots during period?

Yes. During the early stages of your period you may experience increased bleeding with some blood clots. These usually subside in a few days. A menstrual cup can help with heavy clots during periods.

Other causes of blood clots in period are vaginal infection, endometrial thickening, fibroid or (less commonly) cancer. You should inform your doctor if period bleeding is more than 7 days, you pass very large clots, or you feel weak.

Is blood clots during period miscarriage?

If you are pregnant or your period is late and you are having bleeding with blood clots, then it can be due to miscarriage. Other causes of bleeding while pregnant are ectopic pregnancy, infections or spotting during implantation. Any heavy bleeding with pain in pregnancy is an emergency and you should see a doctor immediately.

What causes blood clots during period with pain?

If you have prolonged periods and pain, then it may be due to an infection, endometriosis, adenomyosis or a sign of dysmenorrhea. Both adenomyosis and endometriosis can cause period blood clots with pain. However, this can be relieved with analgesics like ibuprofen or naproxen, and sometimes hormonal treatment. If you have an infection, then antibiotics and pain relief drugs will help, but they should be prescribed by a doctor.

What does big blood clots in period mean?

Blood clots in period may not always be a problem, especially during the first days of menstruation. However, big clots in period (for example larger than a coin or quarter) are usually abnormal. During normal period, blood loss is less than about 80 mls. If you have prolonged periods with big blood clots then you should see your doctor.

Possible causes are:

• Fibroid

• Endometrial thickening (hyperplasia)

• Less commonly, cancer

Learn more: Causes of fibroid and treatment.

What causes blood clots during period bigger than a quarter?

If you have period blood clots larger than a quarter, then you should inform your doctor. It is likely due to a medical problem like submucous fibroid, cervical polyps or endometrial hyperplasia. Further tests such as pelvic ultrasound or biopsy may help confirm the cause.

What causes large blood clots on period?

If you persistently have large blood clots on period then it may be due to any of these causes:

• Vaginal infection

• Uterine fibroid

• Endometrial thickening or polyps

• Endometriosis

• Adenomyosis

• Bleeding disorders or problems with blood clotting

• Perimenopause or hormone imbalance

What should I do? Inform your doctor. If it is too heavy, you can use a menstrual cup or double sanitary protection while you arrange to be seen.

Blood clots in my period, is it bad?

No and Yes. Blood clots in period are normal especially when they are small and subside in few days after your period starts. Very huge blood clots during period, bleeding >7 days, or clots with severe pain, dizziness or weakness are abnormal and may mean there is a problem. Get your doctor informed about your symptoms.

Very large blood clots, is it normal sometimes?

No. If you experience very large blood clots during your period, then you should book an appointment with your doctor. Very large blood clots may be due to:

• Fibroid or adenomyosis (more common in reproductive age)

• Endometrial thickening or, less commonly, cancer (especially if you are more than 40–45 years or after menopause)

Now it’s your turn. Do you have prolonged bleeding with clots? Let us know if we can help.