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Why Unexplained Infertility Is Sometimes Explained During IVF

A blog by Kara Nguyen, MD, MPH , Reproductive Medicine Associates at Jefferson, May 22, 2015

It is humbling to put into perspective that even among fertile couples who have no issues getting pregnant, there is only a 20% chance of achieving pregnancy any given month they try. In other words, even fertile couples are unsuccessful 80% of the time! Most will achieve pregnancy within the first year of trying but others may take longer or never achieve pregnancy at all. Couples who have not achieved a pregnancy after one year of unprotected, well-timed intercourse often seek evaluation by their OBGYN or a fertility specialist.

When couples come to a fertility specialist they want answers. Diagnostic testing is done to identify the major causes of infertility based on their medical history. In about 10% of all cases, a couple (age less than 35 years old) will get a very unsatisfying result: Unexplained infertility. It is important to understand what this really means. The diagnostic testing we have available will only identify the major reasons why a couple may have a difficult time getting pregnant but it certainly can not identify all of the reasons. If the fallopian tubes are blocked or there is no sperm, these are obvious major obstacles to becoming pregnant. There are no tests available for more subtle infertility factors such as inadequate egg quality or fertilization failure.

Among couples with unexplained infertility we also know that despite all of the normal diagnostic testing, they now only achieve pregnancy 1 to 4% during any given month of trying without fertility treatment – much lower chances than 20%! This is why ultimately many couples choose in vitro fertilization (IVF) to help attain their family goals. In fact, a large randomized trial on couples with unexplained infertility called FASTT (Fast Track and Standard Treatment Trial) showed that couples who are unsuccessful after 3 cycles of Clomid (a medication used to stimulate ovulation) and intrauterine insemination (IUI) should proceed to IVF as their next treatment. These couples will more likely become pregnant sooner and will therefore spend less money on fertility treatment.

Oftentimes, subtle infertility factors can be seen during IVF; therefore IVF can also be diagnostic. Even women with excellent ovarian reserve can have inadequate egg quality- which can be seen under the microscope at the time of egg retrieval. Couples with mature eggs and normal semen parameters may have poor embryo development after fertilization which can also only be seen during IVF. Embryo development or implantation issues may even be the issue. These are the diagnostic benefits of IVF that cannot be detected in any other way. In addition, once identified, there are many options for treating and overcoming these infertility factors with the assistance of IVF.

Although IVF does not fix all infertility factors, it is still the most successful treatment option for most couples and affords many bonuses. The risk of multiple gestation (twins, triplets, etc.) can be controlled with the number of embryos that are transferred for example. Comprehensive genetic screening can be done to ensure the best embryos are transferred which increases the pregnancy rate and lowers the miscarriage rate. The woman’s fertility can be preserved by creating surplus embryos which can be frozen at her current age and transferred later when she is ready for baby two or three!

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