Diminished Ovarian Reserve

Diminished Ovarian Reserve can be successfully treated in our Austin Fertility Center

Diminished ovarian reserve refers to a clinical situation in which the ovary does not contain as many oocytes as would be expected for a woman’s age. It is difficult to adequately stimulate (or “superovulate”) a woman’s ovary in the presence of diminished ovarian reserve. Superovulation increases the chance of conception in a treatment cycle by causing more oocytes to ovulate – thereby leading to a better chance for potential fertilization. If it is difficult to stimulate a woman’s ovary, there is limited ability to increase the chance of achieving pregnancy.

Women develop all of their oocytes before they are born.  In fact the number of oocytes that a woman has peaks approximately twenty weeks before she is delivered from her mother’s uterus. At that time, there are 6-7 million oocytes within the ovary; this number declines rapidly from that point forward such that by the time she reaches puberty there are only approximately 500,000 oocytes remaining. As a woman proceeds through a natural cycle at any point in her reproductive life, approximately 300 oocytes try to develop to the point of ovulation. However, usually only one “dominant follicle” releases its oocyte. The remaining oocytes that do not ovulate become atretic, or regress and get absorbed back into the ovarian tissue. The process repeats itself in each subsequent cycle. The rate of loss of oocytes within the ovary is genetically predetermined. Some women will experience a significant decline in the quantity of their oocytes in their forties, while others may experience this much earlier. Those women who experience premature decline are considered to have diminished ovarian reserve.

Although genetically predetermined loss of oocytes is the most common cause of diminished ovarian reserve, there are other causes as well.  Most of these are covered in our website section on premature ovarian failure. In fact, for women under 35 years of age, diminished ovarian reserve is a precursor of premature ovarian failure.

Diminished ovarian reserve can also result from the consequence of the ovary having been damaged or destroyed from disease processes. One of the most common diseases is endometriosis. Other types of benign ovarian tumors and even borderline malignant tumors of the ovary can also destroy ovarian tissue.  Surgical removal of ovarian disease frequently results in the removal of some normal ovarian tissue, as well.  It is also not uncommon for women to lose an ovary from surgery for a fallopian tube problem and/or a surgery for a benign ovarian problem.  In addition to the above described conditions, ovarian tissue may also be destroyed by an autoimmune process in which antibodies attack the follicles that contain oocytes within the ovary.

There are several recommended ways to evaluate a woman’s ovarian reserve. These tests are an important part of the fertility evaluation in some patients as it is possible for women to have diminished ovarian reserve and still have regular, ovulatory cycles.  A basal antral follicle count is one of the most reliable tests for evaluating ovarian reserve.  A transvaginal ultrasound examination is performed in the first few days of the woman’s cycle and the number of small, resting follicles is counted.  In general, if there are at least 8-9 resting follicles the patient is considered to have normal ovarian reserve.  A more common way to evaluate a woman’s ovarian reserve is to obtain serum FSH and serum estradiol on cycle day #2, 3, or 4.  The FSH level should be less than 10-12 miu/ml. An FSH greater than 18 miu/ml suggests a significant reduction in ovarian reserve with a corresponding marked reduction in the chance of achieving pregnancy, even with advanced fertility treatment.

A “gray zone” of ovarian reserve is sometimes defined as a serum FSH between 12 and 17 miu/ml.  It is important to have a serum estradiol performed at the same time as the FSH level.  If the estradiol is under 50, which is considered normal, then the FSH level is more accurate.  If the estradiol level is over 50, the FSH level might be artificially suppressed by the elevated serum estrogen level and therefore be less accurate.  Also if the serum estradiol is over 50, this is considered to be abnormal and indicative of diminished ovarian reserve.  Although patients with diminished ovarian reserve usually do not respond well to superovulation, there are certain superovulation protocols that may allow patients to respond better and increase their chance of conceiving.  If the diminished ovarian reserve is so significant that a woman cannot respond to superovulation, her best option for achieving pregnancy is to undergo a cycle of in vitro fertilization using donor oocytes.

Ovarian reserve testing is a reflection of the quantity of oocytes within the ovary more than a reflection of quality – although many investigators believe that these two characteristics are closely related.  Despite the widespread use of ovarian reserve testing, it appears that age is still the most important predictor of oocyte quality.

Diminished ovarian reserve does not eliminate the possibility of pregnancy. However, this problem should encourage a woman to be more aggressive in her quest to become pregnant as time is clearly of the essence.