Menstrual Blood Clots: What’s Normal?

Most of the time, clots in menstrual blood are normal. Your body makes proteins during your period to stop the bleeding when the period is complete, and clots form in the same way they would if you cut yourself. Menstrual blood also contains tissue from the uterine lining that can be mistaken for a blood clot or mixed in with a clot. Though menstrual clots are usually nothing to worry about, there are times when they can be a symptom of an underlying condition. Here’s what to know about what’s typical and what means it’s time to call the doctor for menstrual blood clots.

During the days of your period when you are bleeding more heavily, the clots are often bright red because they pass quickly. When your flow is lighter, the blood is moving more slowly and darkens over time. The color of the clot, whether it’s bright or dark red, is no reason for concern. If the clots are no larger than a quarter, that’s also normal. Larger clots are more difficult to pass, and your cervix dilates to let them out, which you experience as cramps.

Clots are a cause for concern only if they are bigger than a quarter and you are bleeding heavily (meaning you have to change a pad or tampon every hour). Also watch for severe pain, bruising easily (which can indicate anemia), bleeding through clothing or onto bedclothes, or clots that increase in size. If you notice these symptoms, contact your health provider.

Possible causes for large menstrual blood clots include:

• Uterine fibroids, which are noncancerous tumors

• Polyps, which are small, noncancerous growths on the uterine lining

• Lack of ovulation, which is when the ovaries don’t release eggs

• Bleeding disorders, including von Willebrand disease

• Hormone imbalance, such as underactive thyroid, PCOS (polycystic ovary syndrome), and menopause

• Endometriosis, which is when the uterine lining grows outside the uterus

• Miscarriage, an early loss of pregnancy

• Cancer (rare), a malignancy in the uterus, ovaries or cervix

The treatment for menstrual blood clots will depend on the cause. It may include medication or, in some cases, surgery.

Medications may include:

• Birth control pills (hormone therapy) decrease the menstrual flow. Birth control pills with estrogen and progesterone can reduce menstrual flow by up to half. Progesterone alone can decrease menstrual flow by more than 80%.

• Ibuprofen can reduce the amount of bleeding you have by about half. Do not take ibuprofen for menstrual bleeding without consulting your healthcare provider.

• Antifibrinolytics are drugs that help clotting but also reduce bleeding by about half.

One type of IUD (intrauterine birth control device), is FDA-approved to reduce bleeding by up to more than 90%. If medications or an IUD don’t help, your doctor may recommend surgery to treat the underlying condition that is causing heavy bleeding and large, troublesome menstrual blood clots.

Surgical procedures include:

• Laparoscopy, a type of minimally invasive surgery to remove uterine fibroids

• Myomectomy, the medical term for fibroid removal using a larger incision (‘fibroids’ are leiomyomas)

• Endometrial ablation, which is removal of all or part of the uterine lining; the procedure prevents childbearing

• Dilation and curettage (D&C), where the cervix is dilated and a layer of uterine lining removed; needs to be repeated if lining builds up again

• Hysterectomy, which removal of the uterus

The great majority of the time, menstrual blood clots are a normal part of your period and to be expected. Monitor your periods; if you see an increase in the number or size of your clots, have severe pain, or heavy bleeding that soaks through a pad in less than an hour, contact your provider for a professional evaluation and to see if treatment is advisable.