Ultrasonography to detect ovulation 

Ultrasound monitoring or folliculometry is the most reliable, almost 100% way to detect ovulation. It requires several visits to the ultrasound room during the cycle.

The first scanning is appointed after the end of menstruation, about a week before the expected ovulation, and then repeated every 2-3 days. The interval depends on the individual growth rate of the follicles (the approximate date of ovulation is determined by their size). After a yellow hormone-secreting body (corpus luteum) appears on the site of the dominant follicle, as well as fluid in the pelvis, the doctor establishes that ovulation has occurred.

How to detect ovulation day by ultrasonography?

The accuracy of this method is from the main advantage of ultrasound. However, there are also disadvantages: the high cost and the need to visit hospital. The problem is that before establishing the fact that the follicle is ready for ovulation, it can take more than one day, and you need to pay for each screening.

If the menstrual cycle is stable, but its duration is shorter or longer than 28 days, the first session of the follicular scan is carried out 6 days before the estimated date of ovulation. If menstruation is irregular, folliculometry is prescribed on the 4th day after periods end. In any case, ultrasound monitoring continues every 2-3 days until the fact of ovulation (yellow body and free fluid in the small pelvis) is confirmed.

With a stable 28-day cycle, ultrasounds start from 8-9 days of the cycle. At this time, you can already see the dominant follicle. The following procedures every 2-3 days confirm its growth and maturation and directly indicates the coming of ovulation. When the dominant follicle reaches 18-24 mm it bursts, releasing an egg (ovulation). If the process develops normally, an ultrasound on the 15-16th day of the cycle confirms its onset.

What parameters do the ovaries and follicles have before ovulation?

As the follicle matures, the yellow hormone-secreting body grows and fades away, the size of the ovaries periodically changes. Within the normal range:

  • volume 4-10 см3;
  • length 20-37 mm;
  • width 18-37 mm;
  • thickness 16-22 mm.

ovulationdiary.com logoNote(!): It should not be surprising if an ultrasound shows different sizes of the left and right ovary. This is normal. They come close to equal parameters after menopause.

The main influence on the parameters of the ovary before ovulation is the growth of follicles. At the beginning of each cycle, 7-8 follicles begin to increase in size, then among them, a dominant (less often – two) stands out. It continues to grow, and the rest return to their original state.

The approximate size of the dominant follicle at an early stage (5-7 days of the cycle) is 6 mm. Closer to the middle (day 10), its diameter reaches 15 mm, and then increases by one and a half to two millimeters per day. The size of the follicle during ovulation is 18-24 mm.

ovulationdiary.com logoNote(!): A significant increase in the ovaries (by 1.5 см3 or more), as well as a decrease in parameters, is a reason for an additional examination. In the first case, cysts or tumors may be present. A decrease in volume may indicate fading away of ovarian function.

Ultrasound scanning monitors the growth of a dominant follicle by ultrasound
Ultrasound scanning monitors the growth of a dominant follicle by ultrasound

What are the signs of ovulation seen on ultrasound?

The main indicator of approaching ovulation, which can be well seen with ultrasound scanning, is a dominant follicle with a diameter of 17 mm or more. The natural incubator of a maturing egg is a heterogeneous circular formation. Its double contour with a thickening inside is clearly visible.

ovulationdiary.com logoWhen the size of the follicle on the 12-14th day of the cycle (cycle – 28 days) is less than 15 mm, ovulation may not be occuring.

The uterus during ovulation has a three-layer structure of the endometrium (internal mucous). Its thickness reaches 8-12 mm. After ovulation, the mucous membrane turns into a secretory.

The state of the uterine endometrium determines the readiness of the body for ovulation
The state of the uterine endometrium determines the readiness of the body for ovulation

A thinner endometrial layer may interfere with the implantation of a fertilized egg.

Ovulation with PCOS – what is an ultrasound for?

PCOS (polycystic ovary syndrome) is a hormonal disease in which the eggs do not mature completely inside the dominant follicle and do not leave it. This is a common cause of lack of ovulation. Many follicles with unripe ovules degenerate into benign neoplasms – cysts.

Ultrasound monitoring is commonly used to stimulate ovulation (one of the main methods of conception in PCOS), as well as in a cycle using AI – artificial insemination.

PCOS on ultrasound - there is no dominant follicle
PCOS on ultrasound – there is no dominant follicle

ovulationdiary.com logoDo not be afraid of laparoscopy. This delicate procedure will not only help identify the problem in the reproductive system but also eliminate it locally. So, for example, diathermopuncture – the burning of the ovarian membrane in PCOS, contributes to the onset of ovulation and pregnancy in the next 6 months.

Follicular scan after ovulation

The procedure is carried out in the period of 2-3 days after the expected release of a mature egg.

If everything goes well, the monitor screen shows:

  1. The yellow hormone-secreting body (a rounded formation with uneven contours) in place of a mature follicle. The size of the yellow body after ovulation (15 day of the cycle) is 15-20 mm. It actively grows and reaches, by the 20th day of the cycle, a diameter of 2.5-2.7 cm. Within a week after ovulation, the corpus luteum in the ovary fades and disappears at the time of the next menstruation or vice versa – it increases even more actively (if conception has occurred).
The yellow hormone-secreting body is a temporary gland that forms at the site of the dominant follicle after ovulation
The yellow hormone-secreting body is a temporary gland that forms at the site of the dominant follicle after ovulation
  1. Fluid in the pelvis is the contents of the dominant follicle that occurs after the release of the mature egg, and a small part of the secretion of the fallopian tubes.

If ovulation takes place, the fluid in the adjacent space accumulates in an insignificant volume. Normally, its vertical level is less than 10 mm, but if it exceeds 50 mm, this may be a consequence of various pathological processes in the internal genital organs.

When planning for a child, the best time for intimacy is the day the follicle ruptures or 1-2 days before ovulation.

After ovulation, you need to wait about 7-10 days (so that the embryo is implanted in the uterus). The signs of implantation and other early symptoms of pregnancy at 8-14 DPO are described in a very detailed article with examples. If there are such signs, then an ultrasensitive pregnancy test can be done. If not, you must wait until the delay begins (15 days after ovulation) and then do a pregnancy test.

All readers should be happy with planning and hopefully have healthy kids!

Ultrasound scanning of ovulation – Folliculometry (+ Photo!)