Four patterns of PCOS (A to D) based on which of the three Rotterdam features are present.
The basis: three Rotterdam features
A PCOS diagnosis usually uses three features known as the Rotterdam criteria: irregular ovulation, signs of high androgens (either clinical signs such as excess hair or findings on blood tests), and polycystic ovaries seen on ultrasound. Not everyone with PCOS has all three of these features. Because of this, doctors group PCOS into four patterns, or phenotypes, according to which features are present. For a wider view of diagnosis, see the what is PCOS page.
The four phenotypes A to D
Phenotype A has all three features at once. Phenotype B has irregular ovulation plus high androgens, but without polycystic ovaries on ultrasound. Phenotype C has high androgens plus polycystic ovaries, but with ovulation that is still regular. Phenotype D has irregular ovulation plus polycystic ovaries, but without signs of high androgens. Each pattern reflects a different combination of features, and this is why two people with the same PCOS diagnosis can have very different experiences. This system helps doctors turn a complicated picture into something clearer, even though every person remains unique.
Why phenotypes matter
Phenotypes help explain why symptoms differ from one woman to another, since some patterns lean more towards menstrual problems while others stand out for androgen signs. Some phenotypes are also sometimes linked to differences in metabolic risk, including a connection with insulin resistance. Understanding these patterns can help women feel more understood, because it explains why their PCOS experience may not match someone else’s. However, a phenotype is a way of describing a pattern, not a firm prediction of a person’s future health, and patterns can shift over time.
When to talk to a doctor
Your phenotype is determined by a doctor after reviewing your cycle history, androgen tests, and ultrasound together, because the three features must be interpreted as one picture rather than separately. You are not encouraged to try to work out your own phenotype from a single test result. Treatment is still guided by your individual symptoms and discussed with a doctor, rather than set by the phenotype label alone.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.