Can Infertility Be Unexplained?
The etiology (underlying cause) of infertility in many couples can be determined by various tests as previously described. Yet, there still remains a sizable percentage of couples in whom no obvious cause of infertility can be identified. Some studies estimate that approximately 10% to 20% of patients fall into this category.However, “unexplained infertility” is not necessarily equivalent to “untreatable infertility.” If a couple has prolonged, unexplained infertility with no previous pregnancies, then a number of etiologies are possible.
If a woman is having normal, regular menstrual cycles, it is likely that each month a follicle is growing and that an egg is being released in an appropriate fashion. If pregnancy has never occurred, however, we cannot be sure that the woman’s fallopian tubes are able to trap the egg or that her partner’s sperm are able to swim through the cervix and uterus and find/fertilize the egg in the fallopian tube. In the absence of a previous pregnancy, the question arises as to whether fertilization can, in fact, occur. The scope of this problem is made clear when we look at the fertilization results for patients who undergo IVF with a diagnosis of unexplained infertility.Typically, the rate of failed fertilization with IVF is approximately 2%, but this rate increases dramatically—to approximately 20%—in couples who have prolonged unexplained infertility with no previous pregnancies. Ultimately, failed fertilization may result from problems with either sperm or egg, or both. In such cases of prolonged unexplained infertility, the use of intracytoplasmic sperm injection (ICSI) [see Question 53] can markedly reduce the rate of IVF fertilization failure since ICSI involves the direct injection of a single sperm into a mature egg. If a woman produces a sufficient number of eggs, then one option that we frequently employ is to split the eggs into two groups—ICSI and regular IVF. This split provides a control group, but if fertilization is poor without ICSI then IVF may ultimately prove to have been of diagnostic benefit.
One of the most significant developments in the treatment of infertile couples has been the move away from extensive diagnostic testing and toward a more rapid recommendation to undergo IVF. We often recommend that patients with prolonged unexplained infertility consider IVF with ICSI, as this combination has both diagnostic and therapeutic benefits.
We were never able to diagnose the exact reason that I couldn’t become pregnant. This can be frustrating and scary because there is no clear-cut path to fixing a problem that you can’t define. I remember talking to other women who had more defined issues such as male factor or PCOS and thinking that those would be easier diagnoses to deal with. Luckily, we were able to benefit from the trend of REs to rapidly recommend IVF for patients whose infertility is unexplained.