How PCOS Is Diagnosed

No two women with polycystic ovary syndrome (PCOS) have the exact same symptoms. This makes PCOS diagnosis challenging, as does the fact that many other conditions can present similarly to PCOS. Because of this, a diagnosis of PCOS heavily relies on ruling out other possible causes. To be formally diagnosed with PCOS, you must meet two of the following diagnostic criteria:

  1. Irregular or absent periods
  2. Biological or physical signs of hyperandrogenism (high androgen level) without another medical cause
  3. A string of small follicles (cysts) on an ultrasound examination

These guidelines, referred to as the Rotterdam criteria, are the ones commonly used by endocrinologists in the United States and abroad.

Blood sample taken for analysis
Rafe Swan/Cultura/Getty Images 

Physical Examination

Your healthcare provider will do a complete physical and pelvic exam and look for physical signs of high androgens—like testosterone-induced hair growth (specifically on the face, lower abdomen, back, chest, and nipples). Other signs may include acne, skin tags, male pattern baldness, and acanthosis nigricans (darkened, thick skin on the neck, thighs, armpits, or vulva).

When a woman has infrequent, absent, or irregular periods (eight or fewer cycles per year), it is a sign that ovulation may not be occurring and could indicate PCOS.

It is important to note that women can have a monthly menstrual cycle and still have PCOS. 

Your healthcare provider will ask you about any unusual symptoms you may have noticed, so be sure to mention any of your concerns.

Writing a list before your visit may help you remember important points to ask about. This may include specific facts and figures about the frequency of periods, when they occurred, what happened when you had them, and what other symptoms you had between periods. This can help your practitioner determine if you are ovulating.

Lab Tests

Blood work will most likely be taken. Besides hormonal testing, such as for testosterone, other sex hormones should be checked such as follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin. Your healthcare provider may test for other associated conditions like high cholesterol and insulin resistance.

A newer blood test, which evaluates the anti-Mullerian hormone (AMH) in women, is now being used by some healthcare providers as a diagnostic tool as well.

Transvaginal Ultrasound

A transvaginal ultrasound may be performed to rule out PCOS. In a transvaginal ultrasound, a probe is placed inside the vagina, which allows the healthcare provider to examine the reproductive organs and look for abnormalities. The thickness of the endometrium can be measured.

Oftentimes these follicles are called cysts. There are many women who have cystic-appearing ovaries without symptoms of hyperandrogenism, and many women who have been diagnosed with PCOS who do not have classically cystic ovaries.

Some healthcare providers find the use of transvaginal ultrasound in adolescents unnecessary. 

The diagnosis criteria for PCOS includes the presence of 12 or more small follicles (2 millimeters to 9 millimeters) in each ovary.

Endometrial Biopsy

An endometrial biopsy can be performed to determine if your endometrial tissue is in the correct phase or to test for endometrial cancer, which is seen more frequently in those with PCOS. This risk of endometrial cancer increases with the number of and length of time between missed periods.

The biopsy can be performed in your healthcare provider’s office and is relatively painless, although you may experience minimal cramping during the procedure. During the biopsy, a small amount of tissue is removed from your uterus through a thin catheter placed into through the cervix and into the uterus. This tissue is then analyzed in the context of your cycle and examined for cancer cells.

Differential Diagnosis

Your healthcare provider will look for other conditions in which irregular menstruation is common, such as thyroid disease, hyperprolactinemiaCushing's syndrome, and congenital adrenal hyperplasia.

In thyroid disease, either too little or too much thyroid hormone can disrupt the menstrual cycle and lead to changes in body weight. Thyroid hormone testing is performed to look for these conditions.

Hyperprolactinemia is an increased production of the prolactin hormone by the pituitary gland. This hormone stimulates the production of breast milk, and it may also be increased in PCOS. A magnetic resonance imaging (MRI) scan may be done to look for growths on the pituitary gland.

Cushing's syndrome results when a benign tumor on the pituitary gland or adrenal glands causes too much cortisol and androgens to be produced. The symptoms can be much like PCOS. Diagnostic tests for this disorder include urine and saliva cortisol tests, as well as a dexamethasone suppression test.

Classical adrenal hyperplasia (CAH) is an enzyme deficiency in the adrenal glands that leads to the excessive production of DHEA-S (an androgen) and a lack in the production of cortisol and aldosterone, the other main adrenal hormones. This is usually diagnosed at birth. However, a condition called nonclassical adrenal hyperplasia is the version of this condition that is very similar to PCOS. It leads to the production of the same hormone (DHEA-S), but patients still produce normal amounts of cortisol and aldosterone, so it can go undiagnosed until adulthood. The screening test is for a hormone called 17-hydroxyprogesterone that is measured in the morning.

Other conditions that may need to be excluded, depending on your symptoms, include pregnancy, hypothalamic amenorrhea, and primary ovarian insufficiency.

A Word From Verywell

It can take persistence to reach a diagnosis of PCOS, as it is known to be underdiagnosed or misdiagnosed. Seek a second opinion if your diagnosis is not clear. While this may all seem overwhelming, remember that you are not alone.

PCOS is the most common endocrine disorder among women of childbearing age, therefore, there are many women who have been through this or who currently are. Reach out to a support group and the people who care about you. Following your healthcare provider's advice and learning about your disease are the best ways to manage it.

Frequently Asked Questions

  • How common is PCOS?

    PCOS affects about 5%–10% of women between the ages of 15 and 44. It's often diagnosed in your 20s and 30s, but it can happen any time after puberty.

  • How is PCOS treated?

    While there isn't a cure for PCOS, treatments are available to manage symptoms and complications. Your healthcare provider may prescribe birth control pills for regulating your menstrual cycle or managing acne. Over-the-counter products can help with facial or body hair. For fertility issues, treatments may include medications like Clomid (clomiphene) as well as in vitro fertilization (IVF).

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Aydoğmuş H, Kelekçi S, Elmalı F, Aydoğmuş S. Can we use serum Anti-Mullerian hormone to differentiate the diagnosis between polycystic ovary syndrome patients and healthy women with polycystic ovarian morphology and regular menstrual cycles. Saudi Med J. 39(10):1011-16. doi:10.15537/smj.2018.10.23413

  3. Bachanek M, Abdalla N, Cendrowski K, Sawicki W. Value of ultrasonography in the diagnosis of polycystic ovary syndrome – literature review. J Ultrason. 15(63): 410-22. doi:10.15557/JoU.2015.0038

  4. American Cancer Society. Endometrial cancer risk factors.

  5. Papadakis G, Kandaraki EA, Tseniklidi E, Papalou O, Diamanti-Kandarakis E. Polycystic ovary syndrome and NC-CAH: distinct characteristics and common findings. A systematic review. Front Endocrinol (Lausanne). 10:388. doi:10.3389/fendo.2019.00388

  6. Williams T, Mortada R, Porter S. Diagnosis and treatment of polycystic ovary syndrome. Am Fam Physician. 94(2):106-113.

  7. Office on Women's Health. Polycystic ovary syndrome.

Additional Reading

By Nicole Galan, RN
Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book."