Unexplained Infertility (UI) represents approximately 30% of all cases.
A couple that has been assigned the diagnosis of unexplained infertility (UI) obviously suffers from infertility and has undergone a diagnostic workup that failed to reveal a credible underlying cause for their condition. In other words, the diagnosis of UI is reached by default; it is a negative diagnosis, suggesting that a clinical problem exists but that the probable cause for this problem has remained elusive.
The reasons why underlying problems may not be identified can, of course, vary. One possibility is that there is no one obvious cause for a couple's infertility and that their problem may be the result of multiple minor aberrations in how their respective reproductive systems cooperate. After all, the successful establishment of pregnancy is a highly complex process, and, at least on a theoretical level, one can assume circumstances where male and female fertility, each, are affected only to such a mild degree that standard diagnostic test results would still be considered within normal parameters. Yet, together, the reduction in the couple's combined fertility potential is large enough to cause infertility.