Clomifenstimulation bei Zyklen zur intrazytoplasmatischen Spermieninjektion (ICSI)

Gonadotrophin-releasing hormone antagonists: will they replace the agonists?

Modern gonadotrophin-releasing hormone (GnRH) antagonists such as cetrorelix and ganirelix reliably prevent premature LH surges in controlled ovarian hyperstimulation for assisted reproductive technologies. Cetrorelix and ganirelix are safe and effective compounds. Because of their distinct pharmacological mode of action, it has been possible to achieve a significant reduction of treatment time. Fertilization and pregnancy rates are comparable to those obtained in agonist protocols for ovarian stimulation. No allergic or hyperergic reactions have been reported, and patient compliance is excellent. The fact that GnRH antagonists allow an immediate suppression of gonadotrophin concentrations while preserving pituitary responsiveness to endogenous GnRH provides enormous flexibility in treatment. GnRH antagonists have helped to overcome some major disadvantages of GnRH agonists, especially of the long protocol, which is currently the standard protocol for ovarian stimulation. The mistaken administration of antagonists during early pregnancy is not possible, since they are only administered during ovarian stimulation when a premature LH surge may be imminent. They are used in the spontaneous cycle or after pretreatment with oral contraceptives. Pregnancy can easily be ruled out by testing for human gonadotrophic hormone before onset of gonadotrophin stimulation on the second or third day of the cycle. Since flare-up effects are absent, there is no risk of cyst formation. Hormonal withdrawal symptoms are eliminated, since no period of pituitary suppression occurs, and therefore exogenous gonadotrophins are not required. Overall, the duration of the stimulation cycle is as short as a normal menstrual cycle. The procedure seems to be safer than the long protocol, since the most serious complication, the occurrence of severe cases of OHSS, is reduced. It is also safe with respect to the course of pregnancies and the health of offspring. Both protocols developed so far, the single dose and multiple dose antagonist protocol, are comparable, utilizing data from the large prospective phase IIIb studies. Although several studies have indicated a slight reduction in pregnancy rate with GnRH antagonists as compared with agonists, this problem may be rectified by developing flexible antagonist regimens designed for individual patients. Introducing flexible GnRH antagonist regimens should be the area of research in the near future.

A randomized study comparing IVF in the unstimulated cycle with IVF following clomiphene citrate

The efficiency of IVF in unstimulated cycles was compared with that following ovarian stimulation with clomiphene citrate in a simple protocol with ultrasound monitoring only. A total of 132 couples with no previous IVF attempts, selected by female age <35 years, indication for intracytoplasmic sperm injection or infertility caused by tubal factor or unexplained infertility were randomized to the two protocols. Randomization yielded two comparable groups. The clomiphene group (68 couples) performed significantly better than the unstimulated group (64 couples) in terms of number of cycles with oocyte harvest (90/111 or 81% versus 65/114 or 57%; chi(2) = 9.21, P < 0.002), embryo transfers per started cycle (59/111 or 53% versus 29/114 or 25%; chi(2) = 18.14, P < 0.0001), live intrauterine pregnancy rate per started cycle (20/111 or 18% versus 4/114 or 4%; chi(2) = 12.42, P < 0.0001), live intrauterine pregnancy rate per embryo transfer (20/59 or 34% versus 4/29 or 14%; chi(2) = 3.96, P = 0.047), but not in terms of implantation rate (22/85 or 26% versus 4/29 or 14%; chi(2) = 1.65). Only two twin pregnancies occurred. Modest side-effects were recorded following clomiphene. Accordingly, a simple clomiphene citrate protocol, but not IVF in unstimulated cycles, seems compatible with the concept of 'friendly IVF', yielding a fair pregnancy rate both per cycle started and per embryo transfer in selected patients. The results do not substantiate any important negative anti-oestrogenic effects of clomiphene.