Peritoneal fluid from patients with endometriosis decreases sperm binding to the zona pellucida in the hemizona assay: a preliminary report

OBJECTIVE: To evaluate the effect of peritoneal fluid (PF) from patients with endometriosis on gamete interaction under hemizona assay (HZA) conditions. DESIGN: The HZA was used to study the effect of PF from patients with endometriosis on sperm binding to the zona pellucida using media and normal PF as controls. SETTING: The patients were collected from a university hospital infertility clinic. PATIENTS: Peritoneal fluid from 16 women being evaluated for infertility or sterilization who were found to have endometriosis at surgery was used. Three normal patients, who were being sterilized, had PF that was used as a control. RESULTS: Results suggest that there is a significant reduction in the number of tightly bound sperm to the zona surface in endometriosis specimens as reflected in the hemizona index and that this effect is directly related to the stage of the disease. CONCLUSIONS: Although the sample is small, this methodology may help to elucidate one of the mechanisms responsible for endometriosis-associated infertility.