a doctor cups hands holding illustration of female reproductive system

Endometriosis vs. PCOS: What Are the Must-Know Differences?

Endometriosis and PCOS are two leading causes of female infertility. But they are different diseases that require targeted treatment protocols. Find out other must-know differences between the two.

Endometriosis and Polycystic Ovarian Syndrome (PCOS) are gynaecological conditions affecting women of childbearing age. They are both major causes of female infertility and are complex diseases with poorly understood triggers. Even though there's currently no cure for endometriosis and PCOS, the right treatments may help reduce the severity of their symptoms.

While either of these diseases can impact your chances of getting pregnant, they are two different health conditions that vary in scope, symptoms, and treatments. 

Let’s look at the differences between endometriosis and PCOS

Disclaimer: The information provided in this post is not intended as medical advice.


What Is Endometriosis?

Endometriosis is estimated to affect around 10% of women of childbearing age worldwide [2].

It’s a disease whereby tissues that line the uterus (endometrium) are also found elsewhere throughout the body. In most cases, endometrial-like tissues are located within the pelvic cavity, but they may also be found further away, such as in the lungs [3].

Endometrial-like tissues also respond to the rise in oestrogen that triggers ovulation, thickening initially and shedding off afterwards.

When the endometrium within the uterus breaks down, it’s naturally drained out of the body as period blood via the vagina. Meanwhile, endometrial-like tissues outside the uterus have no opening to leave the body [3].

Over time, this could lead to cysts in the body and internal bleeding. The latter can also cause the organs in the pelvic area to stick together, creating adhesions [3].


How Does Endometriosis Affect Fertility?

Endometriosis is one of the main causes of female infertility, implicating 30-50% of women who have trouble conceiving [1].

At the moment, scientists are still unclear about the exact relationship between endometriosis and infertility. For instance, in a small sample size of 179 women with endometriosis, 66.5% of them were able to get pregnant with sex and artificial insemination [15].

Of course, the more severe your condition, the higher the likelihood of infertility. What’s more, where the endometrial-like tissues are located can also affect your odds of conception. However even if you’re diagnosed with this condition, you can still be able to conceive [16].


What Is PCOS (Polycystic Ovarian Syndrome)?

crumpled note with PCOS written on it

PCOS is a hormonal disorder in which a woman experiences abnormally high levels of androgens and/or the ovaries fail to release an egg every month [4, 17].

If you haven’t heard, androgens are male sex hormones generally produced by the ovaries in small amounts. However, several small cysts may develop on the ovaries when ovulation fails to occur. These cysts produce androgens, which spike the hormone’s level [4].

As you can imagine, PCOS negatively impacts your fertility. What’s more, PCOS is often linked to other health issues like insulin resistance, obesity, and metabolic disorders [17].

On a global scale, a 2020 systemic review estimated that PCOS affects 4-20% of women of reproductive age [5].


How Does PCOS Affect Fertility?

Women with PCOS may experience missed or irregular periods, interfering with the menstrual cycle. You may notice that your menstrual flow may be very light or very heavy. Because ovulation takes place less regularly, getting pregnant while dealing with PCOS may be more challenging [5].

Some women with PCOS may think that using an ovulation test kit to track their fertile period may help improve their odds of getting pregnant. There’s a caveat, though. Most ovulation test kits measure Luteinising Hormone (LH), which regulates your period and tells the ovary to release the egg. Because women with PCOS may experience an LH surge, their test results may be misleading [18].

That said, you can still use an ovulation test kit for menstrual cycle tracking. Try an easy-to-use ovulation test kit, like the twoplus Fertility Ovulation Test Kit, to get insight into your cycle.

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Elevated male sex hormones may also cause bodily symptoms such as:

  • Excess body hair
  • Female pattern baldness (thinning hair)
  • Oily skin
  • Acne

Because insulin resistance commonly accompanies the condition, there may also be stubborn weight gain, especially around the waist, [5]. Aside from the unwanted abdominal fat, high insulin levels can also bring about fertility problems. In fact, research recommends weight loss as an effective way to improve insulin resistance in PCOS individuals. This, in turn, can help boost your ovulation rate for better chances of conception [19].


What Are the Differences Between Endometriosis and PCOS?

From a bird’s eye view, PCOS is caused by hormonal issues, while endometriosis is due to abnormal cell growth outside the uterus. While endometriosis and PCOS share some of the same symptoms, they also have distinct signs that set them apart.


Endometriosis vs. PCOS: Symptoms

Endometriosis [6]

PCOS [7]

Chronic pelvic and/or abdominal pain

Hirsutism (excess hair growth on the face and/or body) or hair thinning

Heavy or painful periods

Irregular periods (e.g., heavy or light, infrequently or too frequently) 

Pain when using the toilet 

Severe acne

Painful sex

Insulin resistance and obesity

In the case of endometriosis, the severity of symptoms may not always reflect the severity of the condition. Some women may feel intense pain with mild endometriosis. Meanwhile, individuals with more advanced endometriosis may feel little to no discomfort [2].


Endometriosis vs. PCOS: Causes and Risk Factors

While hormonal disturbances are present in both endometriosis and PCOS, the causes and risk factors for each are different.


Causes of Endometriosis and Its Risk Factors

What causes endometriosis is still unknown, but the most common theory is that the disease is caused by “retrograde menstruation.” In human-speak, that means some menstrual blood flows backwards into the pelvis through the uterine tubes during your period.

Because the menstrual blood contains endometrial cells, the backflow causes the cells to stick to the reproductive organs or elsewhere in the pelvis, leading to endometriosis [3].

The risk factors of endometriosis include:

  • Beginning menstruation early (before 11 years old)
  • A family history of endometriosis among female members
  • A shorter menstrual cycle
  • Heavy period bleeding for more than a week
  • Infertility
  • Excessively high oestrogen levels

Causes of PCOS and Its Risk Factors

From a medical perspective, PCOS is a complicated hormonal disorder with numerous triggers, including lifestyle and dietary factors [8].

One common observation is that individuals with PCOS also have insulin resistance. This is when insulin accumulates in the body and elevates the androgen levels. Obesity can also promote insulin resistance, worsening PCOS and its symptoms [4].

Risk factors of PCOS include [9]:

  • Obesity
  • Diabetes, including type 2 diabetes and gestational diabetes
  • Excessive presence of male sex hormones 
  • Family history of PCOS
  • Premature puberty (before age 8 or 9)

Endometriosis vs. PCOS: Diagnosis and Treatments

There are a few differences to look out for in terms of diagnosis and treatment for endometriosis vs. PCOS.


Endometriosis: Diagnosis and Treatment Options

For a confirmed endometriosis diagnosis, laparoscopy is required. A thin, flexible tube with a camera is inserted into the body to look for endometrial-like tissues [13].

Treatment for endometriosis will vary according to where the endometrial-like tissue is found. Your healthcare provider may suggest medication, surgery or both. Medication (along with other pain management strategies) is usually used when pain management is the primary goal. If endometriosis impacts your ability to get pregnant, surgery may be necessary to remove the unwanted tissue and improve fertility [6].


PCOS: Diagnosis and Treatment Options

Different tests may be required when diagnosing PCOS, such as calculating your body mass index (BMI) to measure your risk of obesity and conducting a pelvic ultrasound to scan for ovarian cysts or other contributing conditions. Your healthcare professional may also recommend blood tests to check for elevated androgens [14].

Treatment for PCOS primarily focuses on managing symptoms and reducing long-term health implications caused by the condition. Medication may be prescribed to lower androgen levels or address related health problems like cholesterol, diabetes and heart disease. Lifestyle changes may also be helpful, such as reducing body fat and managing stress, anxiety, and mood [8].


Can You Have Endometriosis and PCOS at the Same Time?

concept of endometriosis and PCOS

Yes, it’s possible. In fact, women with PCOS may have a higher chance of experiencing endometriosis, too. A 2014 study found a significant correlation between PCOS, pelvic pain, infertility, and early-stage endometriosis [10].  

This correlation may be due to the hormonal changes brought about by PCOS, as theorised in a 2011 paper. According to the paper’s researchers, abnormally high levels of androgens and insulin typical of PCOS could increase estradiol. As estradiol is a type of oestrogen produced in the ovaries, excess estradiol in your system can intensify your risk of endometriosis [11].

With that said, it’s worth remembering that the exact causes of both conditions — endometriosis and PCOS — are still unknown. While some common symptoms, such as period irregularities and infertility, occur for different reasons. Therefore, no definitive link can be made yet, and both endometriosis and PCOS are still considered separate diseases.


Get Your Next Steps From a Healthcare Professional

Endometriosis and PCOS are common gynaecological conditions that contribute to female infertility. Being different health issues, they need distinct approaches to managing their symptoms and improving fertility outcomes.

If you are experiencing some of the symptoms associated with endometriosis or PCOS, it is worth consulting your primary healthcare provider for a diagnosis and tailored treatment plan.


[1] American Society for Reproductive Medicine, Endometriosis: Does It Cause Infertility?, https://www.reproductivefacts.org/news-and-publications/patient-fact-sheets-and-booklets/documents/fact-sheets-and-info-booklets/endometriosis-does-it-cause-infertility/ 
[2] World Health Organization, Endometriosis, https://www.who.int/news-room/fact-sheets/detail/endometriosis
[3] National University Hospital, Endometriosis https://www.nuh.com.sg/Health-Information/Diseases-Conditions/Pages/Endometriosis.aspx
[4] Johns Hopkins Medicine, Polycystic Ovary Syndrome (PCOS), https://www.hopkinsmedicine.org/health/conditions-and-diseases/polycystic-ovary-syndrome-pcos
[5] National Library of Medicine ,The Prevalence Of Polycystic Ovary Syndrome: A Brief Systematic Review, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879843/
[6] The American College of Obstetricians and Gynaecologists, Endometriosis FAQ, https://www.acog.org/womens-health/faqs/endometriosis
[7] The American College of Obstetricians and Gynaecologists, Polycystic Ovary Syndrome (PCOS) FAQ, https://www.acog.org/womens-health/faqs/polycystic-ovary-syndrome-pcos
[8] Verywell Health, Endometriosis vs. PCOS: What Are The Differences?, https://www.verywellhealth.com/endometriosis-and-pcos-5295536
[9] Sirmans S, Pete K, Epidemiology, Diagnosis, And Management Of Polycystic Ovary Syndrome, https://www.dovepress.com/epidemiology-diagnosis-and-management-of-polycystic-ovary-syndrome-peer-reviewed-fulltext-article-CLEP 
[10] Bruce A. Lessey, MD, PhD et al, Coexistence Of Polycystic Ovary Syndrome And Endometriosis In Women With Infertility, https://journals.sagepub.com/doi/abs/10.5301/je.5000181?journalCode=peva
[11] Journal of Reproduction and Contraception, Is There A Relationship Between Polycystic Ovary Syndrome And Endometriosis?, https://www.sciencedirect.com/science/article/abs/pii/S1001784412600133
[12] larabriden.com, What If You Have Both PCOS And Endometriosis?, https://www.larabriden.com/both-pcos-and-endometriosis/
[13] John Hopkins Medicine, Endometriosis, https://www.hopkinsmedicine.org/health/conditions-and-diseases/endometriosis
[14] Office On Women’s Health, Polycystic Ovary Syndrome (PCOS), https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome
[15] Journal of Gynecologic and Obstetric Investigation, Pregnancy Rate in Endometriosis Patients according to the Severity of the Disease after Using a Combined Approach of Laparoscopy, GnRH Agonist Treatment and in vitro Fertilization, https://www.karger.com/Article/Abstract/365329
[16] Tommy’s, How does endometriosis affect fertility?, https://www.tommys.org/pregnancy-information/planning-a-pregnancy/fertility-and-causes-of-infertility/how-does-endometriosis-affect-fertility
[17] Journal of Nature Reviews Endocrinology, Polycystic ovary syndrome: definition, aetiology, diagnosis and treatment, https://pubmed.ncbi.nlm.nih.gov/29569621/
[18] American Society for Reproductive Medicine, GnRH antagonists for treatment of polycystic ovarian syndrome, https://www.fertstert.org/article/S0015-0282(03)00763-5/fulltext
[19] Journal of Medicine and Life, Insulin resistance and fertility in polycystic ovary syndrome, https://pubmed.ncbi.nlm.nih.gov/20108521/