Period Blood clots: Typical and Atypical Sizes and When to See a Doctor

Key takeaways

• Typical period blood clots are dark red or maroon, ranging from small (pea-sized) to medium (up to the size of a coin), and have a gelatinous texture.
• Small clots are typically normal, but larger clots—those larger than a quarter—might be a sign that something is wrong and you need to see a doctor.
• Treatments for large clots include hormonal therapy, NSAIDs, tranexamic acid, lifestyle changes, and potentially surgical options.
• Consult a doctor if you experience frequent large clots, very heavy bleeding, prolonged periods, severe pain, or symptoms of anemia.

Period or menstrual blood clots are gel-like clumps of coagulated blood, tissue, and mucus expelled from the uterus during menstruation.

They are usually formed when the menstrual blood flow is more severe, than the body can break down, usually during the starting days of the menstrual cycle, leading to clot formation.

Small clots during menstruation are usually harmless, but larger or more frequent clots may suggest a potential health concern.

What do typical period blood clots look like?

Typical period blood clots are usually dark red or maroon in color, and sometimes they can also appear with a brownish tint. They tend to be small and are most common during the heaviest days, which are the first two days of menstrual flow.

The menstrual blood clot appears as thick gelatinous material, which can be as small as a pea or as large as a US quarter coin. They are produced as a result of blood coagulation, which is normal in the menstrual process as the uterus sheds its linings.

The number and size of period blood clots can vary significantly among individuals and can also differ from one menstrual cycle to another. 

What causes the clots in period blood?

Clots in menstrual blood are formed due to the natural blood coagulation process that occurs as the body sheds the uterine lining during menstruation. 

When the lining of the uterus breaks down, blood, tissue, and mucus are released. The body produces anticoagulants to control this blood loss. However, if there is heavy bleeding, the anticoagulants might not work quickly enough, leading to the formation of clots.

Several factors contribute to the formation of these period blood clots, including:

• Hormonal Imbalance: Estrogen and progesterone hormones control the development and breakdown of the uterine lining. When these hormones are out of balance, the lining can become thicker, leading to heavier bleeding and more clots.
• Uterine Fibroids: Noncancerous tumors like fibroids in the uterus can lead to increased menstrual bleeding and the formation of clots.
• Endometriosis: Endometriosis is a condition in which the uterine lining grows outside the uterus, resulting in heavy periods and clots.
• Adenomyosis: This condition occurs when the lining of the uterus develops in the muscular wall of the uterus, leading to heavy bleeding and clot formation.
• Endometrial hyperplasia: Endometrial hyperplasia causes heavy bleeding because the lining of the uterus becomes too thick. This happens when there is too much estrogen and not enough progesterone, leading to the overgrowth of the uterine lining. The thickened lining is unstable and can shed unevenly, resulting in long or heavy periods with more blood loss.
• Intrauterine Devices (IUDs): Certain types of intrauterine devices used to prevent pregnancy, particularly those without hormones, can lead to heavier menstrual periods. This increase in menstrual flow can raise the chances of blood clot formation during menstruation.
• Bleeding Disorders: Bleeding disorders such as von Willebrand disease and hemophilia A and B can result in irregular bleeding patterns, excessive bleeding, and clotting during menstruation. Induced bleeding disorders, such as in patients on aspirin, can also contribute to these symptoms.

Do blood clots only occur in large bleeding?

Blood clots are typically more frequent during heavy menstrual bleeding, but they can also occur during lighter periods. The chances of clots forming increase with the amount and speed of menstrual blood flow. In cases of heavy bleeding, the body’s anticoagulants may not act swiftly enough to stop clots from forming, resulting in clot formation.

However, clots can still happen with lighter periods for several reasons. 

• Hormonal changes, even in light periods, can affect blood clotting. 
• Uterine issues like fibroids or polyps can cause clots, no matter how much you bleed. 
• Blood disorders that affect clotting can lead to clots in any amount of menstrual blood. 
• Also, small pieces of the uterine lining can stick together and form clots even when the bleeding is light.

Period blood clot sizes: When to be concerned?

Period blood clots can come in various sizes, and recognizing the difference between normal and abnormal clots is important for your health.

Small clots, roughly the size of a pea or smaller, are typically considered normal and can occur because the blood is moving slowly enough for the body’s anticoagulants to work effectively, but still form clots in some areas. These small clots are usually not a cause for concern and are a common part of the menstrual cycle.

Medium-sized clots, approximately the size of a coin, can also be normal, especially if they appear occasionally. These clots might happen on days of heavy menstrual flow and are generally not alarming if they don’t occur frequently.

However, clots larger than a quarter, if they happen frequently, might signal an underlying health issue. Consistently noticing large clots is alarming and requires medical attention. 

Large clots could be associated with conditions like hormonal imbalances, uterine fibroids, endometriosis, or other medical problems that might need treatment.

It's important to consult with a healthcare provider if you experience any of the following symptoms:

• Clots larger than a quarter on a regular basis
• Heavy menstrual bleeding that requires changing your pad or tampon every hour for several hours.
• Menstrual periods that extend beyond seven days
• Severe menstrual pain that interferes with daily activities
• Symptoms of anemia, such as fatigue or shortness of breath

Period blood clot vs miscarriage: How to tell the difference?

Distinguishing between menstrual blood clots and those from a miscarriage can be difficult, as both may involve significant bleeding and clotting. However, there are some important differences to consider:

• Timing: Miscarriages generally happen within the first 20 weeks of pregnancy. If you know you are pregnant and encounter heavy bleeding and clots, it might indicate a miscarriage.
• Appearance: Menstrual blood clots are typically dark red or maroon with a jelly-like consistency. In contrast, clots from a miscarriage may contain grayish or more solid tissue and might include a sac-like structure.
• Symptoms: Miscarriages frequently involve severe cramping, lower back pain, and the expulsion of tissue, whereas period-related clots are usually accompanied by the usual menstrual cramps.
• Amount of Bleeding: Miscarriage bleeding can be significantly heavier than a normal period and may not subside without medical assistance. Period bleeding, though it can be heavy, typically follows a consistent pattern and gradually decreases.

Treatments for large blood clots

If you are experiencing large blood clots regularly during your period, it is crucial to consult a healthcare provider. They can determine the underlying cause and suggest appropriate treatment, if necessary. Possible treatments may include:

1. Hormonal Therapy: Contraceptive pills, patches, or hormonal IUDs can assist in regulating menstrual cycles, decreasing heavy bleeding, and preventing the formation of large clots.
2. Nonsteroidal Anti-inflammatory Drugs (NSAIDs): Medications such as ibuprofen and mefenamic acid can help lessen menstrual blood loss and alleviate pain associated with heavy bleeding and clotting.
3. Tranexamic Acid: This prescription drug can help decrease heavy menstrual bleeding and is effective in managing the formation of clots.
4. Lifestyle Changes: Maintaining a healthy weight, managing stress, and staying well-hydrated can also help regulate menstrual cycles and reduce heavy bleeding.
5. Surgical Options: In certain situations, myomectomy (removal of fibroids) or endometrial ablation (removal of the uterine lining) might be required to manage heavy bleeding and prevent clot formation.

When to see a doctor and questions to ask

Period blood clots might not require medical intervention, but it's important to consult a healthcare provider if you experience any of the following symptoms related to period blood clots:

• Clots larger than a quarter
• Heavy menstrual bleeding or periods that last longer than seven days
• Severe menstrual pain that interferes with daily activities
• Symptoms of anemia, such as fatigue, weakness, or shortness of breath

When you see your doctor, you might want to ask these questions to gain a better understanding of your condition and the possible treatments:

• What might be causing my large menstrual blood clots? 
• Are there tests that can identify the root cause of my symptoms? 
• What treatments are available for controlling heavy bleeding and large clots? 
• How can hormonal therapy alleviate my symptoms? 
• Are there lifestyle modifications that could help reduce heavy bleeding and clot formation? 
• Should I worry about any complications from having large blood clots? 
• Are there medications that could help manage my symptoms? 
• What surgical options exist if other treatments don’t work? 
• How can I effectively manage the pain associated with heavy bleeding and clots? 
• How frequently should I schedule follow-ups to monitor my condition?