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The progesterone level in the blood may be measured to confirm that ovulation has taken place. This test is done one week before the date of the next expected menstrual period. A high level indicates that the corpus luteum is producing enough progesterone, and is good retrospective evidence that ovulation occurred. A very low level means that the cycle was most probably anovulatory. An intermediate level may suggest a luteal phase defect (in which the corpus luteum does not secrete enough progesterone).
While the above tests will tell a woman whether or not she ovulates, the following symptoms and tests which can be used in order to determine when you ovulate are of greater importance, since they provide information which can be used to identify the "fertile period" prospectively.
By checking your cervical mucus daily, as described in the chapter on the cervical factor, you can determine when you ovulate. Just before ovulation, your cervical mucus is thin, profuse, clear and stretchy, like raw egg whites. After ovulation, the mucus becomes thick, tacky, scanty and sticky. You can learn to appreciate this change in your mucus (by seeing and feeling it) and this allows you to predict when ovulation occurs quite accurately.
Approximately 25 per cent of women may experience a pain on one side of the abdomen that is associated with ovulation. This is called mittelschmerz (a German word, which means midcycle pain) and is usually related to the release of an egg from the rupturing follicle. It is a good idea to mark the date when it occurs since this information is helpful in determining when ovulation occurs.
The egg develops within a follicle in the ovary. This follicle is a thin-walled structure containing fluid with the egg attached to the wall. Usually, only one follicle develops per month. This follicular growth can be measured by vaginal sonography, with a painless procedure called ultrasound, usually done with a vaginal probe, which projects an image of the ovary onto a screen. The follicle appears as a circular fluid-filled bubble on the screen, and can be seen when it is about 7 to 8 mm in size. It grows at about 1 to 2 mm per day, and is ready for ovulation when it measures 18 to 25 millimeters in diameter.
Following ovulation, the follicle usually disappears from the scan picture completely and this is the best evidence of ovulation. Often, at the same time, fluid can also be detected in the abdomen behind the uterus this is the follicular fluid that is released when the follicle ruptures. Defects detectable by ultrasound are follicles that do not grow at all, or do not grow to a big enough size, or occasionally follicles that do not rupture at the appropriate time (luteinised unruptured follicle). Since ultrasound allows assessment of follicular development, it is especially useful for patients having timed intercourse or having ovulation regulated with fertility drugs. It is usually done on a daily basis, from about the 11th day of the cycle.
Follicle tracking on ultrasound usually takes about 5 minutes to perform. No preparation is needed except that the bladder must be emptied before the scan. Ask to see the picture of the follicle on the monitor - and you should be able to see the growth of the follicle and its rupture for yourself on the screen.
Older ultrasound machines used abdominal probes. These require that the patient has a full bladder, so that the sound waves can reach the ovary. Not only are they much more uncomfortable for the patient (who has to sit waiting till the bladder is almost bursting) but the quality of the pictures is also much poorer as compared to the vaginal scan.
© Dr. Aniruddha Malpani and Dr. Anjali Malpani www.drmalpani.com
Credits: How to Have a Baby: Overcoming Infertility
