Skip to Content

Does endometriosis period blood look different?

Endometriosis is a condition where tissue similar to the lining of the uterus grows outside of the uterus, most commonly on the ovaries, fallopian tubes, and pelvic tissue. This tissue thickens and bleeds each month during a menstrual period, but unlike normal uterine lining, it has no way to exit the body. This leads to inflammation, pain, and the formation of scar tissue.

One of the most common symptoms of endometriosis is painful periods. The appearance of period blood may also look different in some women with endometriosis compared to women without the condition. In this article, we will explore whether endometriosis causes period blood to look different and what those differences might be.

What Makes Period Blood Look Different Normally?

Before examining how endometriosis may alter menstrual blood, it helps to understand what makes period blood vary in appearance normally. There are a few factors that influence this:

Cycle Phase

The makeup of menstrual blood can differ based on what part of the menstrual cycle it is coming from:

– Early cycle (days 1-3): Blood flow is heavier and contains more tissue/clots from shedding the thickened uterine lining. It is typically bright to dark red.

– Mid-cycle (days 3-7): Flow lightens and contains less clotting/tissue. Color appears more reddish-brown or pinkish.

– Late cycle (days 7-end): Flow continues to taper off and blood is thinner with minimal clotting. Color often darkens to a brown/black shade.

Flow Amount

Lighter flows tend to appear more brown or pinkish, while heavier flows appear brighter red as they contain more oxygenated blood.

Use of Birth Control

Hormonal birth control pills or intrauterine devices (IUDs) may lead to lighter, shorter periods. This often results in blood that appears light pink or brown.


Younger women who have recently begun menstruating often have light flows with minimal clotting. The blood may be pinkish or light red.

Heavier, dark red flows with clotting become more common as women reach their 20s and 30s.

Perimenopausal women in their 40s may again have light, variable flows often brown or pink in color.

How Might Endometriosis Change the Appearance of Period Blood?

Women with endometriosis sometimes notice differences in their menstrual blood flow. Potential changes include:

Darker Blood

The blood from endometrial tissue outside the uterus may appear darker than normal uterine lining blood, sometimes being brown or black in color. This is related to it pooling within the body and deoxygenating before being shed.

More Clotting

The misplaced uterine tissue has increased clotting factors. As it sheds each month, it may pass many clots and thick tissue along with blood. Clots may be larger than a quarter in size.

Abnormal Colors

Along with black or brown blood, some women with endometriosis report very dark red, purple, or orange menstrual blood. This may indicate the presence of old blood caused by internal bleeding.

Bright Red Spotting

Some women have persistent spotting of bright red blood between periods when endometrial lesions bleed in small amounts throughout the cycle.

Appearance Possible Causes
Dark brown or black Old blood, deoxygenated before shedding
Increased clotting High clotting factors in abnormal endometrial tissue
Dark red, purple, orange Old blood from internal bleeding
Bright red spotting Lesions bleeding small amounts throughout cycle

Other Symptoms of Endometriosis

While abnormal period blood can raise suspicion for endometriosis, there are other key symptoms as well:

– Painful cramping before and during periods that does not respond to over-the-counter painkillers

– Lower back and abdominal pain unrelated to menstrual cycle

– Pain during sex

– Intestinal upset around periods like diarrhea and constipation

– Abnormally heavy periods with cycles shorter than 27 days

– Infertility and difficulty getting pregnant

– Ovarian cysts

– Fatigue and nausea

If several of these symptoms are present, it is a good idea to see a gynecologist. They can perform tests like pelvic exams, ultrasounds, or laparoscopy to check for endometrial tissue growths.

When to See a Doctor

Consult a physician promptly if you notice any of the following:

– New onset of very heavy, long periods

– Menstrual flow that soaks through a pad or tampon every hour for multiple hours

– Large clots greater than 1 inch (size of quarter)

– Severe cramping not relieved by over-the-counter painkillers

– Periods lasting longer than 7 days

– Foul odor coming from menstrual blood

– Dizziness, weakness, paleness from excessive blood loss

– Unexplained spotting between periods

These can indicate a problem like endometriosis, uterine fibroids, polyps, or other conditions requiring treatment. Catching any abnormalities early improves the chances of preserving fertility.

Diagnosing Endometriosis

If endometriosis is suspected, there are a few approaches doctors can use to confirm diagnosis:

Medical History

Description of symptoms and menstrual history provides clues. Details about pain onset, severity, triggering factors, and impact on daily life help identify endometriosis.

Physical Exam

Pelvic exam may reveal tenderness, nodularity, or enlargement suggesting endometrial deposits.

Transvaginal Ultrasound

Visualizing pelvic anatomy detects endometrial cysts on ovaries and other changes.


Surgery to insert a camera inside the abdomen offers a definitive diagnosis by visually inspecting for endometrial lesions. Biopsies can be taken as well.


Advanced imaging without surgery can identify endometrial growths in some cases.

Tracking symptoms in a journal and communicating openly with your provider makes it easier to get an accurate diagnosis.

How Is Endometriosis Treated?

Once confirmed, endometriosis requires treatment to provide pain relief, reduce progression, and improve fertility. Options include:

Pain Medications

Over-the-counter anti-inflammatories like ibuprofen or naproxen can help manage cramping and discomfort. Some prescription narcotic painkillers may be warranted for severe pain.

Hormonal Birth Control

Suppressing menstrual cycles with birth control pills, shots, implants, or IUDs limits endometrial tissue bleeding and growth. This relieves pain and slows progression.

GnRH Agonists

These IV/injected medications temporarily suppress ovarian function and halt estrogen production to induce a menopause-like state.


Laparoscopic procedures can remove endometrial implants and scar tissue. This provides pain relief and improved fertility chances. In severe cases, hysterectomy may be done.

Alternative Approaches

Diet changes to avoid inflammation, exercise, acupuncture, and nutritional supplements may complement other endometriosis treatments.

The right treatment course depends on symptom severity, impact on fertility, patient age, and other factors. Following up annually helps monitor progression and adjust management as needed.

Coping with Endometriosis

Living with endometriosis presents many day-to-day challenges. Here are some tips for coping:

Track symptoms

Use a pain diary or period tracker app to identify patterns and triggers to share with your doctor.

Manage stress

Anxiety and tension can worsen pain. Try relaxing techniques like yoga, meditation, massage, etc.

Watch your diet

Anti-inflammatory foods like leafy greens, salmon, avocado, berries, and peppers may ease symptoms. Limit red meat, dairy, oils, and highly processed foods.

Exercise regularly

Low-impact activity helps keep muscles loosened and promotes blood flow.

Heat therapy

Heating pads, warm baths, and hot packs can relieve cramping and tension.

Join a support group

Connecting with others who understand your experience provides emotional support. The Endometriosis Foundation of America offers resources.

Communicate needs

Let family/friends know how they can help during painful flares. Adjust social plans as needed.

Coping patiently and allowing time for proper treatment provides the best outcomes for managing endometriosis.


Endometriosis can sometimes cause period blood to look different than typically expected. Abnormalities may include darker black/brown blood, increased clotting, and unusual colors like purple or orange. However, changes to menstrual blood are just one potential symptom of endometriosis. Severe cramping, infertility, bowel issues around periods, and pain during sex or exercise are also common.

If your period blood looks consistently abnormal or your cycles are extremely painful, see your gynecologist. Tests like pelvic exams, ultrasounds, and laparoscopy can provide a definitive endometriosis diagnosis. Hormonal treatments, pain medications, surgery, and alternative therapies can then help manage this challenging but treatable condition. With proper care, it is possible to relieve discomfort, slow progression, and maintain fertility.