The incidence, characteristics, and prognosis of patients whose infertility is unexplained.

Review of the case records of 500 consecutive couples attending one Scottish infertility clinic revealed a group of patients whose infertility remained unexplained after completion of a standard protocol of investigations. The incidence of this condition in the clinic population was 24%. Various patient characteristics were examined, and no differences from patients with a detectable, organic cause for their infertility were found. Life-table analysis was used to provide a prognostic guide for such couples. About 34% of those with primary infertility and 21% of those with secondary infertility will remain infertile after 9 years of attempting to conceive.