Infertility is usually defined as not being able to get pregnant after at least one year of trying (6 months if you are over 35 years of age). Women who are able to get pregnant but then have repeat miscarriages are also said to be infertile.
Reasons for not being able to get pregnant include problems with the man, the woman, or both. In about 15% of infertile couples both have been tested to be ok. This is known as unexplained infertility.
To understand the work-up that's needed to be done for infertility, you need to first understand the major reasons for not being able to get pregnant. The most important and basic components of the process of getting pregnant include the following:
- Male factor: Sperm must be deposited close to the cervix near the time of ovulation, ascend into the fallopian tubes, and have the capacity to fertilize the oocyte.
- Ovarian Factor: Ovulation of a mature oocyte must occur, ideally on a regular, predictable, cyclic basis. But it's not only that ovulation must take place, but the egg has to be of a "good quality".
- Cervical Factor: The cervix must capture, filter, nurture, and release sperm into the uterus and fallopian tubes.
- Tubal Factor: The fallopian tubes must capture ovulated ova and effectively transport sperm and embryos.
- Uterine Factor: The uterus must be receptive to embryo implantation and capable of supporting subsequent normal growth and development.
The infertility testing is done to check each of these components, insofar as that is possible, and to identify any abnormalities that might impair or prevent conception.
- Sperm Count: Does he have enough sperms and are they OK?
- Ovulation: Is the egg released regularly from the ovary each month?
- Egg Quality: Are the eggs good enough and when they fertilize are they recruited during each ovulatory cycle? A normal and low FSH on CD 3 usually means that the eggs have a good quality, while an elevated FSH on CD means their quality is not so good.
- Fallopian Tube Patency: Can the sperm and the egg travel unimpeded through the fallopian tubes to the site of fertilization? Are there adhesions to prevent the tubes from moving normally?
- Implantation: Once fertilized, can the embryo progress and implant into the lining of the uterus?
- Uterine Lining: Is the endometrium adequately prepared to accept and support the embryo?
- Pregnancy Maintenance: Once the embryo has implanted, can the pregnancy be maintained to term?