For about 10% of all infertile couples, the cause of the infertility cannot be readily determined using conventional diagnostic methods. Such cases are often referred to as "unexplained infertility." The truth however is that in most such cases, the diagnosis of “unexplained infertility is in fact presumptive because a more in-depth evaluation would have revealed a cause. This having been said, people diagnosed with so called “unexplained infertility” fall into two broad groups: a) Those couples who don't have any biological problems interfering with pregnancy. b) Those who do but the reason cannot be found due to insufficient medical information or technology. It is in this latter group that improved testing techniques have made infertility easier to diagnose and treat. In order to make even a presumptive diagnosis of “unexplained infertility” the answers to the following questions must be in the affirmative.

• Is the woman ovulating normally?
• Is the couple having intercourse regularly in the periovulatory phase of the cycle?
• Are the fallopian tubes normal and open?
• Can endometriosis be excluded?
• Does the male partner have normal semen parameters (most specifically with regard to sperm count and motility?
• Is the post coital (Huhner) test (periovulatory examination of cervical mucous, done 6-18 hours after intercourse) normal?

The definitive diagnosis of “unexplained infertility” has a lot to do with the thoroughness of the health care provider in excluding all possible causes. The fewer tests performed, the more likely a presumptive diagnosis For Example:

• Abnormalities of the fallopian tubes (adhesions or developmental defects) of the finger-like “petals” at their outer ends of the tubes that help sweep eggs inside (i.e. fimbriae). can prevent eggs from being collected and transported to the awaiting sperm
• Chromosomal abnormalities of eggs or embryos: Eggs must be euploid (contain the right number of chromosomes) to be successfully fertilized and embryos must also be euploid in order to implant successfully in the uterine lining. Until recently there was no reliable method for determining whether eggs and embryos were euploid. The recent introduction of genetic tests such as comparative genomic hybridization (CGH) now allows for identification of all chromosomes in the egg and embryo. As such CGH represents an important addition to the “infertility” diagnostic armamentarium.
• Luteinized Unruptured Follicle (LUF) Syndrome: Here, the eggs can become trapped in the follicle and not be released (trapped ovulation) In such cases routine tests done to detect ovulation ((temperature charting, Urine LH testing, Blood progesterone levels) may be normal resulting in false interpretation that ovulation is actually occurring.
• Ovulation (hormonal) Dysfunction: Abnormalities in ovarian hormone production in the preovulatory phase of the cycle (follicular phase defect) and/or in the postovulatory phase (luteal phase defect) can negatively affect preparation of the uterine lining (endometrium), thus thwarting normal implantation.
• Immunologic implantation dysfunction (IID): Sometimes, the woman’s or the man’s own immune system can attack sperm cells, killing them or causing them to become immobilized. Also, immunologic dysfunction involving the uterine lining can cause the implanting embryo to be rejected so early that the woman does not even recognize that she in fact had conceived.
• Cervical infection; Ureaplasma urealyticum infection of the cervical glands can prevent sperm from migrating through the cervix and uterus to reach the egg(s) in the fallopian tube(s). Such infection will usually not be detectable through routine examination and/or cervical culturing methods.
• Mild or Moderate Endometriosis: Endometriosis is in 100% of cases associated with the production of “pelvic toxins” that reduce the fertilization potential of otherwise normal eggs by a factor of 3-5. In addition, about 1/3 of woman with endometriosis (regardless of its severity) have immunologic implantation dysfunction (IID). Furthermore mild and often even moderately severe endometriosis can only be accurately diagnosed by direct visualization of the lesions through laparoscopy or laparotomy and, the detection of IID requires highly sophisticated tests that can only be adequately performed by a handful of Reproductive Immunology Reference Laboratories in the United States. Finally, a condition called nonpigmented endometriosis, in which the endometrium may be growing inside the pelvic cavity with many of the same deleterious effects as overt endometriosis, cannot be detected even by direct vision (at laparoscopy/laparotomy). The fertility of these patients may be every bit as compromised as if they had detectable endometriosis.
• Psychological Factors: The entire reproductive process is governed by the brain. Thus it should come as no surprise that stress and negativity can interfere with hormonal balance and decrease the ability to conceive.
• Mild Male Factor
• Antisperm antibodies in the man or woman.

Management: Successful management of “Unexplained Infertility” requires that a very individualized approach be taken. Wherever possible the underlying cause should first be identified. Problems that involve ovulation dysfunction (hormonal imbalance) require ovulation induction with oral or injectable fertility drugs. Cervical mucous hostility due to infection with ureaplasma (which is transferred back and forth sexually to both partners) requires specific and concurrent antibiotic therapy. In other cases involving younger women (under 39 years) where there is a problem with sperm migration via the cervix and uterus to the fallopian tube(s) intrauterine insemination (IUI) with or without ovulation induction, is indicated. When these treatments fail, in cases, women over the age of 39 years, in women with IID, in men or women who harbor antisperm antibodies in significant concentrations and in cases associated with tubal abnormalities, in vitro fertilization (IVF) is needed. All cases of intractable, moderate or severe male infertility call for injecting sperm directly into the egg to achieve forced fertilization (intracytoplasmic sperm injection-ICSI). It is an indisputable fact that most causes of infertility can be diagnosed and it is a great pity that the diagnosis of “unexplained infertility” is often used as an excuse for not having performed a full and detailed evaluation of the problem. Couples should not simply accept a diagnosis of “unexplained infertility” at face value since treatment is most likely to be successful when the specific cause of the problem can be fully identified.