Unexplained Infertility - Explained
Approximately 20% of couples struggling to get pregnant are told they have "unexplained infertility." After examinations and tests, the doctor states there is no known medical reason to explain why they haven’t conceived. Hearing this, many couples feel a great sense of frustration and think "if everything is okay, then why isn't it working."
A couple should go to a fertility doctor after trying on their own for 12 months — six months for women over 35 — and undergo an investigation. There are standard tests for both the woman and the man.
To explain the approach to my patients I've coined the term "SEMS," which stands for "Sperm, Eggs, can they Meet, can they Stick," that is to say not miscarry. The term unexplained infertility is used when the sperm quality meets normal standards, the woman is likely to be ovulating regularly with a good ovarian reserve/egg supply, and a "dye test" (hysterosalpingogram) proves that the fallopian tubes are open.
Also, if the doctor suspects the answer may be within the women’s pelvis, then a surgical procedure known as laparoscopy is performed. Laparoscopy is when a surgeon looks into the woman's pelvis in the operating room with a scope. The doctor may find endometriosis, a condition responsible for as much as 15-20% of infertility. Sometimes there, pelvic scarring is identified, which can prevent the transport of the egg into the fallopian tube where it is supposed to meet the sperm and fertilize. If all of these investigations yield normal results, then it is customary to give the couple the diagnosis of “unexplained infertility."
If I reach this diagnosis with a couple, I consider the last part of the SEMS acronym: Stick. The woman may actually be getting pregnant, but miscarrying. In fact, it has been estimated that 70% of all pregnancies fail; it just happens so early that the woman is not aware. Recurrent Pregnancy Loss is then the diagnosis.
Unfortunately checking for all the causes can be costly. A careful review of the patient's history and that of her family might give some clues. Blood tests are drawn to check for a blood clotting disorder or immune disorder that may be preventing the embryo from implanting in the womb. A hysteroscopy — an outpatient procedure where the doctor actually looks inside the uterus to see if there is a structural issue inside that may be preventing embryo from adhering to the wall — should be performed. After excluding recurrent pregnancy loss, I then give the couple the diagnosis unexplained infertility.
Even though the couple’s infertility is “unexplained," treatment to help them have a baby can proceed. Couples with unexplained infertility are excellent candidates for insemination therapy if the woman's egg supply is adequate. Insemination, or IUI, is when sperm are collected, washed, and introduced into the uterus at the time of ovulation. Success from IUI can be improved if fertility drugs are used, but the risk of twins or more is greatly increased. It is considered good practice, to limit IUIs for unexplained infertility to just three or four attempts. Approximately 30% of couples with unexplained infertility will be successful that way.
If insemination fails, a fertility doctor will likely recommend in vitro fertilization-IVF. The woman’s ovaries are stimulated with medications and then eggs are collected. Sperm are introduced to the eggs and fertilization occurs in the laboratory. The fertilized eggs start to divide, creating more and more cells. When embryos are formed they are placed into the womb.
It is interesting that the process of IVF will often explain why the couple was not getting pregnant. The eggs may be found to be of poor quality when observed under a microscope. Sometimes there is no fertilization of the eggs after the sperm are introduced, raising the question about the quality of the sperm because they failed to penetrate the wall of the egg. In fact, failure of fertilization is so common in couples with unexplained infertility that it has been recommended for these couples to inject the sperm into the egg, a process known as Intra-Cytoplasmic Sperm Injection-ICSI.
It is common in cases with unexplained infertility to see embryos that simply do not divide well. When this occurs we feel like we are on the right track in identifying the couple’s problem, but unfortunately the reason for poor quality embryos is poorly understood.
The good news for couples with unexplained infertility is fertility treatments help them as well or better than couples with a known diagnosis. Perhaps the best news for couples with unexplained infertility is the problem often resolves spontaneously. Last year, a study was published looking at all the couples who got pregnant on their own after completing fertility treatments, successful or unsuccessful, and nearly all of them came from the category "unexplained infertility."
Unfortunately, so often the woman’s age, egg reserve, or “biological clock” prevents us from taking a hands-off approach. Couples travelling on this journey are frustrated and stressed, but should take heart and work with their doctors because the prognosis is quite good.