Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder that affects women of reproductive age, impacting hormonal balance, metabolism, and reproductive health. Many people believe that irregular periods, such as infrequent or absent menstruation, are a mandatory feature for a PCOS diagnosis. This widespread misconception can lead to a delayed diagnosis for individuals who experience other symptoms but maintain a regular monthly cycle. It is entirely possible to have PCOS even with predictable menstrual bleeding, and understanding the full range of diagnostic indicators is important. The condition still requires careful medical evaluation and management.
The Three Pillars of PCOS Diagnosis
Healthcare providers most commonly utilize the Rotterdam criteria, which defines the syndrome by the presence of any two out of three specific conditions. These three criteria are chronic anovulation or oligo-ovulation, clinical or biochemical signs of hyperandrogenism, and the presence of polycystic ovarian morphology on ultrasound.
The first criterion, oligo- or anovulation, refers to irregular or absent menstrual periods. Since a diagnosis only requires two of the three criteria, a woman with a regular cycle can still meet the requirements by displaying the other two features. A diagnosis of PCOS can be confirmed if she presents with signs of androgen excess and polycystic ovaries on imaging. Before confirming the diagnosis, other endocrine disorders that can mimic these symptoms, such as thyroid dysfunction or hyperprolactinemia, must first be ruled out.
Recognizing Signs of Androgen Excess
For women with regular cycles, elevated androgens are highly likely to be one of the two confirming factors for a PCOS diagnosis. Hyperandrogenism refers to higher-than-normal levels of androgens, often called “male hormones,” such as testosterone. This hormonal imbalance can be detected through clinical signs visible on the body or through specific blood tests.
The most common clinical sign is hirsutism, which is the growth of coarse, dark hair in a male-pattern distribution, such as on the face, chest, or inner thighs. Hirsutism is objectively measured using a standardized scoring system. Other skin-related signs include persistent, severe acne resistant to standard treatments, and androgenic alopecia, which is male-pattern thinning of the hair on the scalp.
The presentation of these clinical signs can vary significantly based on a woman’s ethnic background and genetic predisposition. For example, some women may have high androgen levels but show minimal hirsutism, while others may experience significant hair growth with only mildly elevated hormones. Biochemical signs involve blood tests to measure circulating androgen levels, primarily free testosterone and dehydroepiandrosterone sulfate (DHEA-S). Free testosterone is the biologically active form, and its elevation, even when total testosterone is normal, is a common indicator of hyperandrogenism in PCOS.
The Significance of Ovarian Structure
The third diagnostic pillar involves evaluating the structure of the ovaries using ultrasound imaging to identify polycystic ovarian morphology (PCOM). The term “polycystic” in this context is often misleading, as it does not refer to large, pathological cysts but rather to an excessive number of small, undeveloped follicles. These structures are fluid-filled sacs, each containing an immature egg, that have arrested their development due to the underlying hormonal imbalance.
Under the Rotterdam criteria, PCOM is defined by having 12 or more follicles measuring 2 to 9 millimeters in diameter in at least one ovary, or by an increased ovarian volume greater than 10 milliliters. This follicular excess is a structural indicator of dysfunctional follicular development, a hallmark of PCOS. The appearance on the ultrasound is often described as a “string of pearls” around the outer edge of the ovary.
Having polycystic ovaries on its own is not enough for a PCOS diagnosis. Many healthy women, particularly adolescents, can have this ovarian morphology without any other symptoms of PCOS. For a woman with regular periods, the PCOM finding must be paired with clinical or biochemical hyperandrogenism to meet the diagnostic threshold of two out of three criteria. This combination confirms the presence of the hormonal and structural changes associated with PCOS, even when the menstrual cycle appears regular.