Low Egg Yields And ICSI
Intracytoplasmic sperm injection (ICSI) is often used in combination with IVF treatment to improve the chances of embryo fertilization and therefore pregnancy. Because the ICSI procedure involves injecting a single sperm cell into a single egg, in the hope that fertilization will take place, this technique is often recommended for male patients who have low sperm counts or poor sperm quality. However, the benefits of ICSI are not only directed at men. This fertility treatment can also help women who would otherwise have difficulty getting pregnant even through IVF (in-vitro fertilization). Patients for whom IVF is less likely to succeed include women whose ovaries produce only a small number of eggs at the retrieval stage of IVF.
Not Enough Eggs
The IVF procedure requires a woman to take hormones that suppress her natural menstrual cycle and force her ovaries to produce more eggs than they normally would. When the follicles on the ovaries reach maturity, the eggs growing inside them are retrieved or "harvested" by the IVF specialist at the patient's fertility clinic.
This is done under anesthetic. The doctor pushes a long, thin needle through the wall of the vagina into the ovary follicles and uses the needle to suck out the liquid inside the follicles. The hope is that most of the follicles will release an egg with the liquid, which can then be fertilized using sperm cells. In some cases, however, only a few eggs are produced. Fertility specialists often hope for a 70% retrieval rate - namely, 70 % of the follicles should produce eggs.
Candidates For Low Yields
IVF treatment is obviously not equally successful for each patient. Patients who are likely to have low egg yields during IVF include:
- Older women
- Women whose reproductive systems don't respond well to the ovulation-inducing medications given during IVF
- Women who have high levels of follicle stimulating hormone during IVF treatment
- Women whose ovaries produce only a small number of follicles
- Women whose ovaries are difficult to reach during the retrieval process
- Women who are overweight
ICSI To The Rescue
If not enough eggs are retrieved from the ovaries, the fertility doctor has a problem. Even in an IVF treatment cycle in which a lot of eggs are available, not all these eggs will be successfully fertilized by sperm and become embryos, and even then probably not all the embryos transferred to the uterus will implant. So if a woman starts off with a small number of eggs, her number of embryos will be even smaller, and the IVF treatment is more likely to fail. This is where ICSI comes in. By injecting a sperm cell into each of the few eggs that are available, an embryologist can increase the number of embryos available for transfer to the woman's uterus, and thereby boost her chances of getting pregnant.
Freezing ICSI Embryos
Even in the case older women, whose chances of embryo implantation are lower, it's considered unethical to transfer more than 3 embryos to the uterus, due to the risk of multiple pregnancy. Therefore, a woman who has had a low egg yield during IVF, but has an excess of fertilized embryos thanks to ICSI, may choose to freeze these embryos and keep them in storage. The embryos can be used should the current cycle of IVF fail, or to conceive future pregnancies in the years to come.