Clinical management of low ovarian response to stimulation for IVF: a systematic review.
Poor response is not a rare occurrence in ovarian stimulation. Although not fully accepted, the most dominant criteria for poor ovarian response are small numbers of follicles developed or oocytes retrieved, and low estradiol (E2) levels after the use of a standard stimulation protocol. There is no ideal predictive test as the poor responder is revealed only during ovulation induction; however, increased levels of day 3 FSH and E2 as well as decreased levels of inhibin B can be used to assess ovarian reserve. Several protocols have been proposed for clinical management of low ovarian response in IVF. Although high doses of gonadotrophins have been used by the vast majority of authors, results have been controversial and prospective randomized studies have shown little or no benefit. The few available relevant studies do not indicate that recombinant FSH improves outcome. Flare-up GnRH agonist protocols (including all dosage varieties) produce better results than standard long luteal protocols. Luteal initiation GnRH agonist 'stop' protocols were shown to improve ovarian response according to prospective studies with historical controls, but this was not confirmed by well-designed prospective, randomized, controlled studies. The few available data obtained with GnRH antagonists have not shown any benefits. Adjuvant therapy with growth hormone (GH) or GH-releasing factors results in no significant improvement. The use of corticosteroids reduces the incidence of poor ovarian response in women undergoing IVF treatment. The limited data obtained with nitric oxide donors are encouraging. Pretreatment with combined oral contraceptives prior to stimulation may help ovarian response. No benefit was observed with standard use of ICSI or assisted hatching of zona pellucida. Finally, natural cycle IVF has produced results which are comparable with those obtained with stimulated cycles in true poor responders. Well-designed, large-scale, randomized, controlled trials are needed to assess the efficacy of these different management strategies.