Polycystic Ovary Syndrome (PCOS) is diagnosed when a combination of features are present. These include symptoms such as weight gain, acne, excess hair growth and irregular periods, hormone imbalance in the form of raised testosterone levels, and the appearance of multiple cysts on the ovaries on a scan. Not all of these features need to be present to make the diagnosis so it is technically possible to have PCOS without actually having cysts on the ovaries.