Endometriosis and polycystic ovary syndrome (PCOS) are disorders that affect people who have vaginas who are of reproductive age. This includes people between ages 12 to 52.

Both conditions cause menstrual problems, which can lead to heavy bleeding. They can also make it difficult to get pregnant.

The other symptoms are different, however. They also involve different hormonal issues. Endometriosis is linked to excess estrogen, a female hormone. PCOS is caused by excess androgens, or male hormones. It’s also possible to have both conditions at the same time.

In turn, the conditions cause different symptoms and require different treatments. Let’s explore the difference between endometriosis vs. PCOS.

Endometriosis and PCOS share some symptoms, including heavy bleeding and difficulty getting pregnant. But most of the symptoms are different.

It’s also possible to have these conditions without any symptoms. Sometimes, the symptoms might be subtle or misdiagnosed.

heavy bleedingheavy bleeding
bleeding between periodsirregular periods
painful periodsmissed periods
pelvic pain before periodspelvic pain
pain during or after sexexcess body hair
painful urination or bowel movementshair loss on head
difficulty getting pregnantdifficulty getting pregnant
digestive issuesacne
fatigueoily skin
low energydark, thickened skin (hirsutism)
weight gain
bleeding without ovulation

Endometriosis and PCOS are common among people who have vaginas and are of reproductive age.

For endometriosis, one 2018 study estimated that 10 to 15 percent of women have it, and that it affects about 70 percent of women with chronic pelvic pain.

With PCOS, a 2017 study found that it affects 5 to 20 percent of women of childbearing age. The same study also found that about 80 percent of women who are experiencing infertility due to lack of ovulation have PCOS.

Let’s go over the two conditions in a little more detail.


The tissue that lines your uterus is called the endometrium. Endometriosis occurs when tissue similar to the endometrium grows in other parts of the body.

The condition is associated with high levels of estradiol, a type of estrogen. Estradiol is responsible for uterine tissue growth.

Endometriosis typically affects reproductive organs, such as:

  • outside of the uterus
  • fallopian tubes
  • ovaries
  • uterosacral ligaments
  • peritoneum
  • anywhere between the bladder, uterus, and vagina

It may also affect areas outside the pelvic cavity, including the:

The tissue may thicken and bleed during your menstrual cycle, like the tissue in your uterus. This can cause pain, inflammation, and infertility.


PCOS is a hormonal disorder that affects your ovaries. The primary characteristics of PCOS include:

  • irregular or no periods
  • high levels of androgens
  • cysts in one or both ovaries

If you have PCOS, you’ll likely have at least two of the above conditions. It’s possible to have PCOS without ovarian cysts.

The exact causes of endometriosis and PCOS are unknown. However, researchers have identified possible explanations.


  • Retrograde menstruation: This happens when uterine tissue flows through fallopian tubes and into the pelvic cavity during your period.
  • Immune system problems: Retrograde menstruation affects almost all people who have vaginas and who are menstruating, but the immune system normally manages it. However, if you have an immune system problem, endometriosis may occur.
  • Coelomic metaplasia: Some cells may turn into endometrial cells, which may explain endometriosis that occurs in areas far from the uterus.
  • Endometrial cell transport: Your lymphatic system or blood vessels may carry endometrial cells to other areas.
  • Post-surgery implantation: After some surgeries, like a hysterectomy, endometrial cells might implant themselves at the surgical site.


  • Hormonal imbalance: High levels of certain hormones, like testosterone, may contribute to PCOS.
  • Insulin resistance: If your body is unable to effectively use insulin, your insulin levels may be too high. This can make your ovaries produce more male hormones.
  • Inflammation: Excess inflammation can also lead to high levels of male hormones.

Certain risk factors increase your chances of developing these two conditions.


  • family history of endometriosis
  • starting menstruation early (before 11 years old)
  • short menstrual cycles (less than 27 days)
  • heavy menstrual bleeding for more than 7 days
  • infertility
  • never giving birth

It’s worth noting that you can still develop endometriosis if you’ve given birth.


  • family history of PCOS
  • diabetes
  • being overweight or obese
  • rapid weight gain

Being overweight can increase your risk of insulin resistance, leading to diabetes. But it’s possible to develop PCOS if you aren’t overweight.

You can have endometriosis and PCOS at the same time. In fact, a 2015 study found that women with PCOS are more likely to be diagnosed with endometriosis.

Another 2014 study determined that there’s a strong link between endometriosis and PCOS with pelvic pain and/or trouble getting pregnant.

According to an older 2011 study, the high levels of androgens and insulin in PCOS could indirectly increase estradiol. This may increase the risk of endometriosis.

Your doctor will use several tests to determine if you have endometriosis, PCOS, or both.

Generally, your doctor will use these tests if you have symptoms like irregular periods. But if don’t have symptoms, you may receive a diagnosis while you’re being treated for something else.


  • Medical history: A doctor will ask about pre-existing conditions and if you have relatives with endometriosis.
  • Pelvic exam: They’ll check for scars and masses.
  • Imaging tests: An imaging test, like an ultrasound or MRI, produces detailed images of your organs.
  • Blood tests: This can identify abnormal levels of inflammatory markers and hormones.
  • Laparoscopy: A surgeon creates a small incision and checks for abnormal tissue growth.


  • Medical history: Your family history and health status can help a doctor determine if PCOS is a possible cause.
  • Pelvic exam: This allows them to look for cysts and other growths.
  • Ultrasound: An ultrasound creates an image of your ovaries and uterus.
  • Blood tests: Abnormal hormonal levels of inflammatory markers may indicate PCOS.

Both conditions are treated with various forms of medication and surgery.


Treatment focuses on reducing estrogen and pain. Options include:

  • Medication for estrogen: Medication, like birth control, can help reduce estrogen and regulate growth of endometrial tissue.
  • Pain medication: Over-the-counter pain medication may provide relief.
  • Surgical removal of tissue: A surgeon removes endometrial tissue growth.
  • Hysterectomy: Hysterectomy, or removal of the uterus, may be recommended if you’re not trying to conceive.
  • Lifestyle changes: A balanced, nutrient-rich diet can help manage your symptoms.


The goal is to induce ovulation and decrease androgens. Treatments include:

  • Medication: If you’re trying to conceive, you can take medication to trigger ovulation. If not, you can take birth control or diabetes medication to reduce androgens.
  • Acne or hair medication: These drugs help manage acne or excess hair growth.
  • Laparoscopic ovarian drilling: If ovulation drugs don’t help, your doctor might recommend this surgery. It destroys the androgen-releasing tissue in the ovaries.
  • Weight management: A healthy diet and regular exercise could help you lose weight, which may manage your symptoms.

Visit a gynecologist if you have:

  • pelvic pain
  • pain or bleeding between periods
  • increased menstrual bleeding
  • irregular or no periods
  • pain during or after sex
  • difficulty getting pregnant

In both endometriosis and PCOS, early diagnosis is key for controlling symptoms. That’s why it’s important to attend your annual gynecology checkups.

You may also be referred to endocrinologist, or a doctor that specializes in hormones.

In endometriosis, uterine tissue grows in other parts of the body, causing pain and infertility. It’s linked to high estrogen levels, so treatment focuses on reducing estrogen and pain.

PCOS, on the other hand, is due to high levels of androgens. It may cause infertility and ovarian cysts.

Endometriosis and PCOS are common. It’s also possible to have both at the same time. If you have abnormal periods or difficulty conceiving, visit your gynecologist.