Polycystic Ovarian Syndrome (PCOS) is a complex hormonal condition, and Ultrasound remains one of the cornerstone criteria for its diagnosis. At Talwar Fertility & Child Health Centre, we use high-sensitivity Transvaginal Sonography (TVS) to identify polycystic ovaries in approximately 75% of women who present with clinical symptoms of PCOS.

What are Antral Follicles?

Antral follicles are small, fluid-filled sacs in the ovary (measuring 2-9 mm) that contain immature eggs. In a normal menstrual cycle, these follicles grow over 10-12 days until one “dominant” follicle is selected to release an egg. However, in PCOS, this selection process is often disrupted.

Diagnostic Ultrasound Criteria for PCOS

Medical guidelines for PCOS have evolved to become more precise. Here are the key ultrasound markers we look for:

Why Accuracy Matters

Identifying the exact nature of polycystic ovaries helps in tailoring fertility treatments. Whether it is ovulation induction or managing insulin resistance, a clear ultrasound mapping of the ovarian stroma and follicle distribution allows us to predict how your body will respond to medication.

A baseline ultrasound of the ovaries is a critical step in assessing a woman’s reproductive health. It helps us evaluate the ovarian reserve, track the menstrual cycle, and screen for abnormalities. Here is what we look for in a normal, healthy ovary during a scan.

1. Anatomy and Volume

The ovaries are oval-shaped structures located on either side of the uterus within the ovarian fossa.

• Mean Volume: Approximately 4.9 ml is considered normal.
• Position: They usually lie near the internal iliac artery and vein, though their position can vary.

2. Antral Follicle Count (AFC)

The best time to evaluate the ovaries is on Day 2 or Day 3 of the menstrual cycle (Follicular Phase). During this time, we measure Antral follicles (small sacs containing immature eggs) ranging from 2-9 mm.

3. Ovulation and Color Doppler

In a natural cycle, one follicle becomes “dominant,” reaching a size of 17–24 mm before releasing the egg (ovum).

• Blood Flow: Normal stromal blood flow velocity is 6–12 cm/sec. Flow velocity typically increases just before and immediately after ovulation.
• Corpus Luteum: After the egg is released, the follicle transforms into the Corpus Luteum. On ultrasound, it appears as a round cystic mass with thick, echogenic walls.
• The “Ring of Fire”: On Power Doppler, the Corpus Luteum displays a characteristic “Ring of Fire” appearance due to highly increased blood flow around it.