Folliculometry is a diagnostic ultrasound procedure used to monitor the growth and development of ovarian follicles during the menstrual cycle. It helps doctors evaluate ovulation and determine the most fertile period for conception. The examination is commonly recommended for women who are planning pregnancy, undergoing fertility treatment, or experiencing irregular ovulation.
A follicle is a small fluid-filled structure inside the ovary that contains an immature egg. During the menstrual cycle, several follicles begin to grow, but usually one becomes dominant and reaches maturity before ovulation occurs. By performing a series of ultrasound scans, doctors can observe how the follicles develop and estimate the exact timing of ovulation.
When is folliculometry performed?
The timing of folliculometry depends on the type of menstrual cycle and the purpose of monitoring. In a natural cycle or during intrauterine insemination (IUI), monitoring usually begins around the 9th or 10th day of the cycle. During IVF treatment, scans may start earlier, often from the 5th or 6th day.
In most cases, several ultrasound examinations are required throughout the cycle. Monitoring may continue until the dominant follicle reaches the size associated with ovulation, which is generally between 18 and 22 mm.
How is the procedure done?
Folliculometry is performed using a transvaginal ultrasound examination. The examination is usually simple, painless, and takes approximately 10–20 minutes.
During each visit, the doctor evaluates:
• The number of developing follicles
• The size and growth rate of the follicles
• Signs of approaching ovulation
• The thickness of the uterine lining
Follicles typically grow about 1–2 mm per day until they reach maturity.
Why is folliculometry important?
Folliculometry provides valuable information about a woman’s reproductive health and is widely used in fertility assessment and treatment. It can help:
• Determine whether ovulation occurs normally
• Identify the most fertile days for conception
• Monitor response to ovulation-stimulating medications
• Support fertility treatments such as IVF or IUI
• Evaluate menstrual irregularities and ovulation disorders
The procedure may also be recommended for women with a history of infertility, recurrent miscarriage, or conditions such as polycystic ovary syndrome (PCOS).
Are there any risks or side effects?
Folliculometry is considered a safe and minimally invasive procedure. No significant side effects or risks have been associated with routine ultrasound monitoring. Because the procedure does not involve radiation and provides detailed information about follicular development, it has become an important tool in modern reproductive medicine.