In simple terms: an ultrasound scan using a small probe placed inside the vagina to see the ovaries and uterus clearly.
Why it matters for PCOS
Because the probe sits closer to the ovaries, a transvaginal ultrasound gives a clearer view of follicles than a scan through the abdomen. Doctors use it to count small follicles and check ovarian volume, which is one of the three Rotterdam criteria for PCOS. The ovary finding alone does not confirm PCOS; it is read alongside symptoms, cycle pattern, and hormone blood tests.
This scan is usually not offered to people who have never been sexually active or who are uncomfortable with it, and an abdominal scan is used instead. Ask your doctor which scan type suits your situation.
This glossary is education, not diagnosis. For your own situation, ask a doctor or pharmacist.