Endometriosis and Bleeding Between Periods: What You Need to Know


Once they've entered their reproductive years, most women experience a monthly period. The menstrual cycle lasts approximately 28 days and consists of four stages:

  • Follicular Phase: A cluster of ovarian follicles forms on the surface of the ovary, each containing an immature egg. 
  • Ovulation: One of the follicles ruptures and releases a mature egg into the fallopian tube.
  • Luteal Phase: The ruptured follicle evolves into a structure called the corpus luteum. The corpus luteum releases estrogen and progesterone, which thickens the endometrium to prepare for pregnancy.
    • If pregnancy doesn’t occur, the corpus luteum withers and dies. As hormone levels drop, the endometrium collapses and prepares to shed during menstruation.
    • In the event of pregnancy, the menstrual cycle is disrupted and menstruation won’t occur.
  • Menstruation: The endometrium and unfertilized egg shed through the vagina. This marks the beginning of a new cycle and is more commonly known as your period.

The menstrual cycle rarely runs like clockwork and fluctuations are normal. But, heavy bleeding outside your regular period is not normal.

By ‘heavy,’ we mean enough blood to require the use of menstrual hygiene products, like pads and tampons. Unexpected or unusual bleeding between periods is also called intermenstrual bleeding or metrorrhagia.

There are many reasons you might experience heavy bleeding between periods, including endometriosis. This article dives deep into this reproductive condition including causes, symptoms, and treatments.

What Is Endometriosis?

Endometriosis is a condition where endometrial tissue grows outside the uterus, known as 'implants'. Endometriosis is often painful, affecting approximately 10% of women of reproductive age, according to The American College of Obstetrics and Gynecologists (ACOG).

The most common areas to find implants are in the ovaries, fallopian tubes, and tissues around the pelvis. It’s very rare for implants to be found beyond the pelvis region.


What Causes Endometriosis?

Doctors don’t know the exact causes of endometriosis. But, there are a few reasons endometrial tissue might travel and grow outside the uterus, as outlined by Women’s Health and The Mayo Clinic.

  • Menstrual flow issues: Sometimes, menstrual blood may flow up the fallopian tubes and into the pelvis—known as retrograde menstruation. When this happens, endometrial cells may stick to other organs and continue to grow.
  • Genetics:  Endometriosis tends to run in families.
  • Immune system problems: Women with endometriosis often suffer from immune system disorders and certain cancers.
  • Hormones: Higher levels of estrogen are linked to endometriosis. This 'induction theory' suggests hormones cause stomach lining cells to transform into endometrial-like cells.
  • Surgery: Endometrial cells may accidentally transfer to the abdomen during surgeries like C-Sections. This is sometimes called ‘surgical scar implantation.’
  • Endometrial cell transport: Endometrial cells can move through the body by the lymphatic system or blood vessels.

Risk Factors 

As mentioned above, it’s believed that endometriosis is an inherited condition. There’s a laundry list of other factors that place you at a higher risk of developing the condition. Risk factors are generally linked to how much estrogen you’re exposed to in your lifetime.

Women are at a higher risk of developing endometriosis if they:

  • Are in their late reproductive years and have never given birth.
  • Start menses at a very young age.
  • Enter menopause later in life.
  • Experience short menstrual cycles (less than 27 days).
  • Experience heavy and long menstrual periods (longer than seven days) and period pain.
  • Have a low BMI (body mass index).
  • Have a medical condition that affects menstrual flow.
  • Have reproductive tract abnormalities.

Endometriosis is also linked to certain medical conditions, as outlined by Women’s Health. For example, allergies, asthma, auto-immune diseases, and fibromyalgia may put you at a higher risk of endometriosis.

Symptoms of Endometriosis

The main symptoms of endometriosis are intense abdominal pain, painful and heavy periods (known as dysmenorrhea,) and/or heavy bleeding between periods.

Other symptoms of endometriosis include:

  • Painful sex
  • Constipation or diarrhea
  • Back pain, especially lower back pain
  • Pelvic pain
  • Nausea and bloating
  • Painful bowel movements
  • Painful urination
  • Extreme period pain
  • Infertility

Symptoms can range from nonexistent to extremely severe. Yet, the degree of pain does not equal the severity of the condition itself. So, if you experience any of these signs and symptoms–no matter how mild–we recommend seeking medical advice right away.

A Note on Infertility and Endometriosis

There is a very strong association between infertility and endometriosis. Around 40% of women with infertility also suffer from endometriosis, according to ACOG.

Endometriosis causes a lot of inflammation within the reproductive organs. The inflammation may harm the egg or sperm, or prevent fertilization by blocking the sperm from getting to its destination (a.k.a. the egg.)

Rest assured, getting pregnant and having a successful pregnancy is still possible if you have endometriosis. Many women with endometriosis get pregnant and give birth with no complications. However, you should seek medical advice before trying to get pregnant.

It's likely that  your doctor will advise you not to wait to get pregnant. This way, you may avoid any issues down the road in case your endometriosis causes more damage to your reproductive organs. 

Endometriosis: Diagnosis & Treatment

The diagnosis of endometriosis isn’t always straightforward. The symptoms are similar to those of pelvic inflammatory disease, irritable bowel syndrome (IBS), and ovarian cysts. This often leads to misdiagnosis or confusion around diagnosis.


When you visit your doctor, the first thing she'll do is perform a pelvic exam. If she feels anything unusual, she may also want to do an ultrasound. These non-invasive exams check for abnormalities like cysts or scarring caused by endometriosis.

In more severe cases, your doctor may recommend invasive testing like laparoscopic surgery. This type of surgery involves a very thin instrument inserted into the navel. A tiny camera at the end of the scope lets the doctor examine the implants and even take some tissue for a biopsy.

Magnetic resonance imaging (MRI) is another method to test for endometriosis if you're going the surgery route.


There’s good news and bad news when it comes to the treatment of endometriosis. The bad news is that there is no cure. 

The good news is that there are ways to manage and treat it to help relieve some of the painful symptoms. First and foremost, make sure you find a doctor you trust and feel comfortable with. Dealing with conditions of the reproductive tract is always a sensitive matter.

As a first resort, your doctor will likely prescribe pain relievers (e.g. ibuprofen) and non-steroidal anti-inflammatory drugs (NSAID) to help reduce inflammation. Other medications that help lower estrogen levels may shrink the endometrial tissue. Some examples of these medications include:

  • Hormonal birth control (for those not trying to conceive).
  • Gonadotropin-releasing hormone (GnRH) agonist (for those trying to conceive).
  • Aromatase inhibitors.

In more extreme cases, surgery might be necessary. The most common type of surgery to treat endometriosis is ‘conservative surgery’. This procedure removes the endometriosis using a laparoscope, leaving your reproductive organs intact. Your doctor will often recommend taking hormonal treatments in addition to the surgery to help reduce pain.

This type of surgery is a good option, especially for women who still want to get pregnant. It also helps avoid complications a hysterectomy (removal of the entire uterus) may cause down the road. Only in very rare and extreme cases, will endometriosis need a hysterectomy.

Other simple treatments you may also try at home include using a heating pad on your lower abdomen and taking a warm bath. Many women find this helps relax your pelvic muscles and ease some of the pelvic pain or back pain.

In Summary

If you experience bleeding between periods along with pain in your lower abdomen and pelvis area, it may be endometriosis.

Abnormal or irregular bleeding could also be a sign of serious conditions as well. So, if you experience any of the following, please visit your doctor ASAP:

  • Heavy periods with a lot of clotting and period pain, or bleeding between periods.
  • Abdominal pain or cramping.
  • Pain or a burning sensation when peeing.
  • Painful bowel movements.
  • Unusual vaginal discharge and/or redness and itchiness.

If it turns out you have endometriosis, don't panic. While it may not be curable, it is treatable—especially if you catch it early.