THE CONTRIBUTION OF SUBTLE OOCYTE OR SPERM DYSFUNCTION AFFECTING FERTILIZATION IN ENDOMETRIOSIS-ASSOCIATED OR UNEXPLAINED INFERTILITY - A CONTROLLED COMPARISON WITH TUBAL INFERTILITY AND USE OF DONOR SPERMATOZOA

This study aims to determine the relative contribution of oocyte and/o r sperm dysfunction to the reduction of fertilization rates in vitro i n cases of minor endometriosis and prolonged unexplained infertility, The results of in-vitro fertilization (TVF) treatment with ovarian sti mulation have been compared between couples with the above conditions and women with tubal infertility las control for oocyte function) and the use of donor spermatozoa las control for sperm function). Fertiliz ation and cleavage rates using husband's spermatozoa were significantl y reduced in endometriosis couples (56%, n = 194, P < 0.001) and furth er significantly reduced in couples with unexplained infertility (52%, n = 327, P < 0.001) compared with tubal infertility (60%, n = 509), U sing donor spermatozoa the rates were the same as using husband's sper matozoa in tubal infertility (61%, n = 27) or endometriosis (55%, n = 21) but significantly though only partly improved with unexplained inf ertility (57%, n = 60, P < 0,02), In unexplained infertility, a signif icantly increased proportion of couples experienced complete failure o f fertilization and cleavage in a cycle (5-6% versus 2-3%), However, c omplete failure was not usually repetitive, and the affected couples d id not account for the overall reduction in fertilization and cleavage rates, which remained significantly lower in the rest of the unexplai ned and endometriosis groups. Implantation and pregnancy rates appeare d similar in ail groups. The benefit of IVF treatment in cases of mino r endometriosis and prolonged unexplained infertility is due to supera bundance of oocytes obtained by stimulation. The reduction in natural fertility associated with endometriosis appears to be at least partly due to a reduced fertilizing ability of the oocyte, In unexplained inf ertility, there is distinct impairment due to otherwise unsuspected sp erm dysfunction but probably also oocyte dysfunction,