Ovulation of a single dominant follicle during treatment with low-dose pulsatile follicle stimulating hormone in women with polycystic ovary syndrome.

Ten women with clomiphene-resistant chronic anovulation associated with polycystic ovary syndrome were treated with purified urinary FSH (urofollitrophin). The gonadotrophin was given s.c. by pulsatile infusion pump starting at a low dose (1 ampoule or 75 U/d) and increasing by 37.5 U/d at weekly stages in an attempt to induce ovulation of a single follicle. Seventy percent of the 33 cycles were ovulatory and in 18 of these (78%) a single dominant follicle developed and ovulated. Each of the 10 women ovulated when the optimum dose was reached and five of these women became pregnant. The maximum dose of FSH in uni-ovulatory cycles was 150 U/d or less. Endogenous LH concentrations which were raised at the onset of treatment were suppressed in the late follicular phase. The rate of follicular growth and gonadal steroid concentrations were consistent with those observed in spontaneous ovulatory cycles. This study demonstrates that by using low-dose gonadotrophin therapy it is possible to find the 'threshold' dose of FSH to promote maturation of a single dominant follicle. The high rate of ovulation and pregnancy suggest that this approach is of practical importance in treatment of infertile patients with polycystic ovaries.