An endometrial factor in unexplained infertility.

OBJECTIVE To study a group of women with unexplained infertility to see whether they have a defect that is intrinsic to the endometrium. DESIGN Evaluation of the functional response of the endometrium by examining endometrial biopsy specimens using immunohistochemical methods in a group of women with unexplained infertility and in a control group of women with normal fertility. PATIENTS 27 Women with unexplained infertility (average age 33.2); median duration of infertility five years. A control group of 44 women with normal fertility (average age 33.8) who were requesting sterilisation or reversal of sterilisation. SETTING Infertility clinic, Jessop Hospital for Women, Sheffield. INTERVENTION Secretory phase endometrial biopsy specimens were taken, with informed consent, as an outpatient procedure. MAIN OUTCOME MEASURES Immunohistochemistry with monoclonal antibody D9B1, was used to assess the production and secretion of an oligosaccharide epitope produced by endometrial gland cells between two and seven days after the luteinising hormone surge. A reflected light measuring system was used to assess the amount of epitope within the gland cells, and in the gland lumen. RESULTS In the control group of women, mean reflected light measurements at the cell base and cell apex peaked at three and five days after the luteinising hormone surge respectively, and in the gland lumen the epitope accumulated rapidly from three days, reaching a peak at seven days. In the women with infertility the peaks of epitope at the cell base and cell apex were lower, broader, and delayed in onset, and the build up of epitope in the gland lumen was retarded. The synthesis and secretion of the epitope in the women with infertility was therefore significantly reduced and delayed, even in the presence of normal concentrations of circulating progesterone. CONCLUSIONS The results suggest that a primary dysfunction of the endometrium might be associated with hitherto unexplained infertility.