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Endometriosis vs PCOS

Endometriosis vs. PCOS: Understanding These Distinct Conditions

Endometriosis and PCOS are two distinct conditions with different causes, symptoms, and treatments. They can both have severe impacts on a woman’s health and fertility, and understanding their differences can help patients navigate their conditions with the help of their physicians. 

What is Endometriosis?

Endometriosis is a painful medical condition that affects many women. It occurs when the endometrium (the tissue that normally lines the uterus) grows beyond the uterus and into other parts of the pelvic area

Endometriosis most commonly affects the ovaries, fallopian tubes and bowels, and the pelvic region behind the uterus. In rare cases, endometrial tissue can spread beyond the pelvis to other body areas.

During normal menstruation, the endometrial tissue swells, bleeds, and is shed from the uterine lining. When endometrial tissue grows outside the uterine wall, it can swell and form scar tissue, causing pain and discomfort. 


In most cases, endometriosis is characterized by severe pelvic or lower-back pain, usually occurring during menstruation. Pain levels can vary widely, ranging from mild discomfort to debilitating pain.

Other common symptoms of endometriosis may include:

  • Heavy menstrual bleeding or irregular bleeding between periods
  • Pain during and after sexual intercourse
  • Painful bowel movements or urination
  • Constipation and diarrhea
  • Pelvic cramping
  • Fatigue
  • Nausea and vomiting 
  • Infertility


Diagnosing endometriosis often involves a combination of medical history, review of symptoms, physical examination, and imaging tests.

Diagnosis is typically confirmed through:

  • Pelvic exam to check for abnormalities, such as cysts or tender areas
  • Imaging tests, including ultrasound or MRI scans 
  • Laparoscopy, which allows for visual confirmation of endometrial tissue outside the uterus and may involve tissue removal for biopsy


There is currently no cure for endometriosis and no certain method for its prevention. With proper treatment and medical attention, it can be well managed. Treatments vary and depend on the patient’s symptoms. 

In milder cases, treatment of symptoms may include over-the-counter or prescription pain relievers, and birth control pills to regulate hormones. Other medications include progestins and gonadotropin releasing hormone analogues. 

If the condition does not respond to treatment with medication, minimally invasive laparoscopy surgery to remove excess endometriotic lesions may be required.

Severe cases may require a hysterectomy, which involves the removal of the uterus and cervix, and possibly removal of ovaries. This may help to eliminate severe pain. However, it’s considered a last resort form of treatment because it causes infertility in women of childbearing age.

What is PCOS (Polycystic Ovary Syndrome)?

Polycystic Ovary Syndrome (PCOS) is a common but complex hormonal disorder that affects women of childbearing age. It’s caused by the excess production of certain hormones called androgens, often associated with insulin resistance. 

In normal ovulation, the egg ruptures through the outer surface of the ovary. In women with PCOS, high androgen levels cause an excess number of small eggs to grow and interfere with ovulation, resulting in the accumulation of eggs under the outer capsule of the ovary. 


PCOS is one of the most common causes of irregular menstrual cycles and infertility because increased androgen interferes with the development and release of eggs. It may also cause metabolic changes that result in weight gain and hormonal changes that result in acne, excess body hair, and even male pattern baldness.

PCOS symptoms typically start around the start of menstruation and may include:

  • Irregular or missed periods
  • Hair growth on face and chin
  • Acne or oily skin
  • Weight gain or difficulty losing weight
  • Darkening of the skin around the neck or other body folds
  • Male-pattern baldness or thinning head hair
  • Infertility

PCOS is associated with other related health disorders, including obesity, insulin resistance, high blood pressure, and high cholesterol. Additionally, PCOS can increase the risk of developing uterine cancer in adulthood.


Early diagnosis is important to treat symptoms most effectively and prevent complications from associated conditions. 

For PCOS diagnosis, doctors look for at least two of the three following symptoms:

  • Irregular or infrequent periods
  • High levels of specific hormones on blood tests (or hormonal symptoms, such as acne)
  • Enlarged ovaries with multiple immature follicles, viewed with ultrasound


Although PCOS is not curable, there are many treatments available to reduce its impacts on health, fertility and appearance. Due to the systemic effects of PCOS, it requires a multidisciplinary team of physicians, which may include:

  • Endocrinologists
  • Gynecologists
  • Fertility experts
  • Primary care providers
  • Cardiologists
  • Weight loss experts
  • Dermatologists
  • Mental health providers
  • Nutritionists 

Nutrition and weight loss programs are important to help improve symptoms and prevent other negative health consequences. A medication called Metformin may be prescribed to help control blood sugar levels and obesity.

Many patients use hormone therapy to regulate their periods and improve excess hair growth and acne. Aesthetic programs like laser hair removal help with unwanted hair growth.

For women struggling to conceive, medications can be used to promote ovulation. 

Endometriosis vs. PCOS

While both endometriosis and PCOS are common gynecological conditions affecting women, they have distinct characteristics. 

Endometriosis involves the abnormal growth of endometrial tissue outside the uterus, leading to symptoms like pelvic pain and infertility. PCOS is a hormonal disorder characterized by irregular periods, excess androgen levels, and polycystic ovaries. Unlike endometriosis, PCOS can cause weight gain and hormone-related symptoms, such as acne. 

Neither condition is curable, but there are ways to manage symptoms and improve quality of life. Medications are available for each condition, and for severe endometriosis, surgery is a treatment option. 

Collaborating with a team of physicians is important to develop a treatment plan that addresses the unique symptoms and challenges related to both endometriosis and PCOS.

  • Xun Lian, MD
    Obstetrics and Gynecology
    Clinical Assistant Professor

    Dr. Lian is a gynecologist specializing in minimally invasive gynecologic surgery (MIGS). She completed her residency and fellowship at Stony Brook Medicine. Her clinical interests include laparoscopic and robotic approaches to treatment of benign gynecological conditions.

This article is intended to be general and/or educational in nature. Always consult your healthcare professional for help, diagnosis, guidance and treatment.