Each egg grows in a fluid-filled follicle (a small balloon-like structure) in the ovary. The follicle grows in size during the first few days after your period. Normally, ovulation (when an egg escapes from its follicle) occurs usually around the twelfth to fourteenth day of your cycle.
There are basically three ways by which we try to make sure that we collect mature eggs, two hormone tests and ultrasound.
Hormone tests: During IVF treatment, the hormones oestrogen and progesterone are produced in increasing amounts. Regular blood tests will detect the increase.
Measurement of oestrogen can help predict whether or not the ovaries are responding sufficiently well to justify proceeding to the next stage, egg collection. This is particularly helpful in some patients who do not respond well to stimulation of the ovaries.
Oestrogen measurement may give an indication that the ovaries are responding to the fertility drugs too vigorously. This early sign seems to be helpful sometimes in avoiding some of the more serious complications of ovarian over-stimulation.
Ultrasound: the swelling follicle can be directly measured using ultrasound. Ultrasound is usually done daily. In recent years, ultrasound has become more and more accurate and sophisticated, and our equipment is regularly upgraded in order with the advancing technology.
Ultrasound measurements are also indirectly useful in timing egg collection because with ultrasound we can assess the thickness of the uterine lining – the endometrium. A reasonably thick endometrium tends to argue that the uterus is fairly “ripe” and will be shortly ready to receive an egg or an embryo.