What is the gold standard test for diagnosing polycystic ovary syndrome (PCOS)?

The gold standard test for diagnosing polycystic ovary syndrome (PCOS) is pelvic ultrasound. This imaging technique allows for the visualization of ovarian morphology, which is crucial for identifying the presence of multiple ovarian cysts—a key feature of PCOS. In women diagnosed with this condition, the ultrasound often reveals enlarged ovaries with a characteristic "string of pearls" appearance due to the presence of numerous small cysts.

While other tests, such as serum total testosterone and oral glucose tolerance tests, can provide valuable information regarding hormone levels and metabolic function, they do not offer the same direct visual confirmation of ovarian changes that ultrasound does. A fasting lipid panel can help assess cardiovascular risk factors but also lacks the specificity for diagnosing PCOS. Therefore, pelvic ultrasound remains the most definitive tool for confirming the diagnosis based on the presence of morphologic ovarian changes.