Читать книгу Assisted Reproduction Techniques - Группа авторов - Страница 148

Historically a “long” protocol with pituitary desensitization using a GnRH agonist was used although this has now largely been replaced by the GnRH antagonist protocols in women with PCOS. If a long protocol of GnRH agonist treatment is followed by treatment with one of the “pure” or recombinant FSH preparations, one must also be aware that the lack of LH changes the usual relationship of follicle number to circulating estradiol levels. In this situation measurement of serum estradiol concentrations underestimates follicle development. It is therefore essential that endocrine monitoring is supported by high quality ultrasound, otherwise low circulating estradiol concentrations may encourage further and inappropriate gonadotropic stimulation despite adequate follicular development. Indeed, these days, most use ultrasound as the keyway of monitoring follicular growth. Meta‐analyses of the different gonadotropin preparations have indicated no significant differences in the risk of developing OHSS [6].

For the patient with overstimulated ovaries who is approaching the time of human chorionic gonadotropin (hCG) administration several strategies to make treatment safer may be considered. The first is to administer a low dose of hCG to initiate oocyte maturation (i.e. not more than a single injection of 5,000 IU, rather than the dose of 10,000 IU which many clinics use in routine practice) and, in patients receiving GnRH agonist treatment and who therefore require luteal support, to give progesterone rather than hCG (which is virtually obsolete now as a form of luteal support).

Insulin resistance and compensatory hyperinsulinemia contribute to the pathogenesis of PCOS. A number of studies have investigated the effects of using the insulin sensitizing agents, mainly metformin, on women with PCOS undergoing IVF treatment. The use of metformin as an adjunct for IVF is associated with no significant difference in live birth rates (OR 1.39, 95% CI 0.81 to 2.40, five RCTs, 551 women, low‐quality evidence), but a significant lowering of the incidence of OHSS (OR 0.29; 95% CI 0.18 to 0.49, eight RCTs, 798 women, moderate‐quality evidence), but with a higher incidence of gastrointestinal side effects [7]. However, as stated, the GnRH agonist regimens have been superseded by the use of GnRH antagonist regimens for women with PCOS undergoing IVF.