-MEASUREMENT OF OVARIAN RESERVE
Age has a direct effect on the reproductive potential of a woman and until puberty the reproductive potential of a young female child is locked. At the two extremes of a woman’s reproductive career, the menstrual cycle is irregular and mainly anovulatory. While this is due to the immaturity of the HPO axis immediately after puberty, irregular ovulation and menstruation is due to a depletion of the ovarian follicles in the ovary, at the other end of a woman’s reproductive career, few years prior to menopause.
Very early within her mother’s womb, the unborn female child or fetus produces millions of oocytes or eggs. From around 5 to 7 months of pregnancy, it however looses the ability to produce any more oocytes. Furthermore, from about 6 to 8 million follicles present in the ovaries at this age, only about 1 to 2 million follicles are present at the birth of a female child. This is because most of the follicles and their containing oocytes gradually die leaving the best oocytes and follicles to survive as long as possible in the ovaries. This process continues such as by the child reaches the age of puberty, only about 400,000 follicles are present in both ovaries. While most of these follicles eventually die, as a woman grows older, only about 400 follicles are eventually ovulated and have the opportunity of becoming a baby throughout a woman’s lifetime. So it is right to say that as a woman ages, so does the numbers and the quality of follicles left in the ovaries reduce.
The ovarian reserve refers to an estimation of the number and quality of the ovarian follicles left in the ovaries. It has a direct relationship with the fertility potential of a woman. By the age of 37, a significant reduction in the ovarian reserve and hence the fertility rate occur in almost all women. Towards the late 40s to early 50s, ovulation and menstruation occur occasionally and irregularly, ceasing completely at menopause due to lack of ovarian follicles in the ovaries. Because miscarriages are nature’s way of getting rid of abnormal embryos formed from defective gametes, the rate of miscarriages also increases with the age of a woman.
As women in recent years delay child birth till late into their reproductive years, probably for social, academic or occupational reasons, more and more women are faced with the challenge of difficulty in getting pregnant late in their 30s and 40s due to poor or dwindling ovarian reserve. It is therefore important that ways of assessing the ovarian reserve of women presenting with infertility at the upper extreme of the reproductive age group, are developed in order to advise such women, on their fertility potential, on the ideal option of infertility treatment, and on the prognosis of the various methods of treating infertility in such women. Not unusual, women with poor ovarian reserves do not only struggle to conceive, they often require advanced infertility treatment options such as IVF with donor eggs prior to embryo transfer.
MEASUREMENT OF OVARIAN RESERVE
Various methods are employed for estimating the ovarian reserve of women at advanced reproductive age who are faced with the challenge of the difficulty in conceiving. Though many are still in the research level, methods of measurement of ovarian reserve can be grossly divided into ultrasound methods and biochemical methods. Often times a combination of both method are employed.
1. THE ULTRASOUND SCAN
The ultrasound scan measurement of various dimensions of the ovary such as the ovarian volume and the mean ovarian diameter can be used as an indirect measurement of the ovarian reserve. Generally speaking, as the ovarian reserve reduces, the ovarian volume and mean ovarian diameter reduces.
An antral follicular count refers to an ultrasound count of the total numbers of antral follicles present in both ovaries at the beginning of the follicular phase of a menstrual cycle. It is one of the most accurate means of assessing the ovarian reserve of a woman. A large follicuar count is in keeping with a good ovarian reserve while a small or scanty follicular count indicates the presence of a very poor ovarian reserve.
2. BIOCHEMICAL MARKERS
These include the use of the serum FSH assay and serum AMH assay. While the serum FSH assay must be done within the 2nd to the 5th day of the menstrual cycle, the serum AMH can be done at any time of the menstrual cycle. Generally speaking, the higher the serum FSH level and the lower the serum AMH level, the poorer the ovarian reserve, while the lower the serum FSH level and higher the serum AMH level the higher the ovarian reserve. Other biochemical markers that may be used for assessing the ovarian reserve include oestradiol and inhibin B assay. For more information, please CHAT WITH OUR CONSULTANTS.
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