'Unexplained infertility' results of secondary investigations in 95 couples.

Abnormalities of in-vitro sperm-mucus penetration, ovarian hormone deficiency, specifically poor progesterone surge, and luteal cyst formation were assessed prospectively in 95 couples with fully investigated primary infertility of greater than or equal to 3 years duration. Abnormal sperm-mucus penetration was found in 22, half of whom could have been identified on semen assessment alone. Ten other males had recurrent oligospermia but with normal motility and mucus penetration. Twenty-one patients had a poor progesterone surge and seven of them demonstrated retained luteal phase cysts. Endocrine and mucus penetration abnormalities did not coincide, demonstrating that they are distinct and unrelated phenomena. A significant number of couples were found for whom the term 'unexplained infertility' was no longer applicable and appropriate management could be considered.