Ovarian Ultrasonography in Polycystic Ovary Syndrome

Polycystic ovarian morphology (PCOM) on ultrasonography is a cardinal feature of polycystic ovary syndrome (PCOS). The relevance of polycystic ovaries to the clinical spectrum of PCOS was reinforced by the recent findings of the 2018 International Evidence-Based Guideline for the Assessment and Management of PCOS. Similar to other cardinal features, PCOM is not required for the diagnosis of PCOS. Rather, the guideline recommends that the presence or absence of PCOM be established to enable the identification of the complete PCOS phenotype. At minimum, identification of PCOM on ultrasonography requires skilled assessments of antral follicle number and ovarian size in order to accurately gauge the presence of follicle excess and/or ovarian enlargement. Other ultrasonographic features of ovarian morphology including characteristics of the ovarian stroma or follicle arrangement may be helpful in corroborating the presence of PCOM but have less diagnostic accuracy for the condition of PCOS. In this chapter, we review the evolution of criteria used to define PCOM on ultrasonography and provide a basis for follicle excess and ovarian enlargement to define PCOM. Practical considerations related to the reproducible evaluation of ovarian features are provided and their potential utility as biomarkers of health outcomes across the reproductive life course discussed.