What is PCOS
UPDATED: JANUARY 2026
PCOS is known as polycystic ovary syndrome - a reproductive and metabolic condition. It’s name slightly acts as misnomer as many people that I talk to explain “I don’t have cysts on my ovaries” when I bring up PCOS. The truth is, as science has evolved it’s been recognized that you don’t need polycystic ovaries to have this condition.
As of 2023, the Rotterdam Criteria used to diagnose PCOS was updated. Only 2 of the 3 criteria are needed for a diagnosis. They include:
Irregular cycles and ovulation dysfunction
Biochemical hyperandrogenism or Clinical Hyperandrogenism
Ultrasound and polycystic ovarian morphology or Anti-Müllerian Hormone
Understanding the PCOS Criteria
Irregular Cycles & Ovulation Dysfunction
Irregular Periods
According to the ASRM, irregular menstrual cycles are defined as:
Normal in the first year post-menarche (the first period) as part of puberty
1 to Less than 3 years post-menarche: Cycle is less than 21 days or greater than 45 days
3 years post-menarche to perimenopause: Cycle is less than 21 days or greater than 35 days; or there are less than 8 cycles per year.
1 year post-menarche: More than 90 days for any one menstrual cycle
When irregular menstrual cycles are present, PCOS should be considered and assessed bas on the PCOS Guidelines. I discuss PCOS in Teens in another post.
Ovulatory Dysfunction
It’s really important to know this - your period app cannot definitively tell you that you’ve ovulated. It usually picks a day in the middle of your cycle and labels it with a heart (or butterfly, or whatever).
Paying attention to your body’s cues are important. This would be in the form of cervical fluid, using ovulation predictor kits, and basal body temperature. If ovulation does not happen, this refers to anovulation. Your body is not releasing an egg to be fertilized, so no matter how many times intercourse happens during your cycle, no egg will be fertilized, and pregnancy tests will come back as negative.
Most importantly, ovulation dysfunction can still occur in regular menstrual cycles.
Hyperandrogenism
Biochemical Hyperandrogenism
Androgens are “male” hormones like testosterone. In biochemical hyperandrogenism, free and total testosterone serum levels measured through lab work to determine if they are high (“hyper”).
If someone is on the combined oral contraceptive pill, it’s hard to determine these levels because the pill increases sex hormone-binding globulin (SHBG) and decreases androgen production.
Clinical Hyperandrogenism
Clinical hyperandrogenism is when health care providers are assessing if a person has hirsutism. This is when there is the appearance and growth of thick, dark, male-pattern hair. When hirsutism is present, even on its own, it’s predictive of biochemical hyperandrogenism and PCOS in adults. Acne and male-pattern hair loss is also assessed, but those are considered weaker predictors.
The Ferrimen-Gallway Score is a tool used to assess hair pattern change. A score of 4 – 6 should be used to detect hirsutism, although this is dependent on a person’s ethnicity. Nevertheless, hirsutism appears similar across ethnicities.
Ultrasound & AMH
An ultrasound needs to be done to figure out if you have polycystic ovaries. Basically, you need 12+ follicles that are between 2-9mm or an ovarian volume bigger than 10cm in a single ovary. If attempt to get an ultrasound done, do so on the third day of your cycle (ie. day 3 of bleeding).
Ultrasound and polycystic ovarian morphology
Polycystic ovarian morphology is most accurate when observed using a transvaginal ultrasound. In adults, follicle number per ovary is considered the most effective ultrasound marker to detect polycystic ovarian morphology. More than or equal to 20 follicles in at least one ovary is the threshold for polycystic ovarian morphology.
If the two other criteria have been met (irregular periods/anovulation and hyperandrogenism) then an ultrasound isn’t necessary for diagnosis.
Anti-Müllerian Hormone (AMH)
In adults, serum AMH could be used for defining a polycystic ovarian morphology in adults. AMH is produced by developing follicles, and serves as an indicator of ovarian function. As a person ages, their AMH level decreases. Therefore, it reads that the higher AMH (for chonological age), then the more likely of a polycystic ovarian morphology.
Next Steps
Now that you're familiar with the criteria of PCOS, here's what you can do next:
Track your cycle length
Determine if you're ovulating in real life
Get your blood work done if you’re suspicious
Talk to your doctor about an ultrasound if either the first 2 criteria may not be an issue (ie. lab results are optimal)
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