Pituitary-ovarian dysfunction as a cause for endometriosis-associated and unexplained infertility

This study examines circulating and follicular hormone concentrations and fertilization of oocytes in cycles totally unperturbed by exogenous gonadotrophins in 10 women (25 cycles) with untreated minimal-mild endometriosis and nine women (23 cycles) with prolonged unexplained infertility compared with 16 women (50 cycles) with tubal damage as functional controls. Endometriosis was associated with a significantly longer follicular phase (median 15, 12, 13 days respectively) and reduced oestrogen secretion (median index area under the curve 3063, 3842, 3805 units respectively) compared with controls. Both endometriosis and unexplained infertility had significantly reduced serum luteinizing hormone (LH) surges [median peak serum (LH) 43, 39, 55 IU/l respectively and median area under the curve 661, 687, 823 units respectively] and reduced LH concentrations in follicular fluid (median 19.6, 10.6, 9.2 IU/l respectively). These findings suggest that infertility associated with minor endometriosis and of apparently unexplained aetiology share a common pathophysiology in impaired LH surge secretion. Whether that represents a primary pituitary disorder or is secondary to a defective ovarian signal is discussed.