Can Polycystic Ovaries Be Detected on Ultrasound?

Yes, transvaginal ultrasound is the primary imaging modality used to detect polycystic ovarian morphology—a key diagnostic criterion for polycystic ovary syndrome (PCOS). According to the widely accepted Rotterdam criteria, polycystic ovaries are identified when an ovary contains ≥20 follicles measuring 2–9 mm in diameter and/or has an increased ovarian volume (>10 mL), as measured by three-dimensional ultrasound.

It’s important to emphasize that ultrasound alone cannot diagnose PCOS. The condition requires clinical evaluation of at least two of the following: oligo- or anovulation, clinical or biochemical signs of hyperandrogenism (e.g., hirsutism, acne, elevated serum testosterone), and polycystic ovarian morphology on ultrasound—after excluding other endocrinopathies such as congenital adrenal hyperplasia, hyperprolactinemia, or thyroid dysfunction.

Ultrasound findings must be interpreted cautiously. Many women without PCOS—particularly adolescents and those using hormonal contraception—may exhibit transient polycystic-appearing ovaries. Conversely, some individuals with confirmed PCOS may have normal-appearing ovaries on ultrasound, especially with age-related ovarian reserve decline. Therefore, imaging serves as a supportive tool rather than a definitive diagnostic test.

Standardized scanning protocols—including high-resolution transvaginal probes, strict follicle-counting methodology, and measurement of ovarian volume using the prolate ellipsoid formula—are essential for reliable interpretation. Radiologists and gynecologists trained in reproductive ultrasound should perform and interpret these studies to minimize interobserver variability and avoid overdiagnosis.