Embryo transfer

Induction of follicular growth and ovulation with urinary and recombinant gonadotrophins

Gonadotrophins have been used since the 1930s. By the 1990s, a pure biological extract of FSH was obtained. The increase in the demand for new assisted reproduction techniques led to the creation of recombinant FSH, 99% pure and highly consistent between batches, with no LH activity, and a high specific activity. In gonadotrophin protocols, follicular growth can be monitored with regular ultrasounds and/or hormonal testing, mainly oestradiol in the follicular phase. In assisted reproduction the adoption of ovulation induction strategies with GnRH analogues, control the endogenous secretion of LH, avoiding cancellations due to an early LH surge, and premature ovulation. Depending on the moment when pituitary suppression starts, there are short, ultra-short and long protocols The use of long protocols not only increases pregnancies and live births, it also allows an easier programming and simplifies IVF treatments. Ovarian stimulation entails some risks such as ovarian hyperstimulation syndrome and multiple pregnancies that can be avoided in many cases with an accurate prediction and an active prevention.

A novel ovarian stimulation protocol for use with the assisted reproductive technologies

OBJECTIVE

To determine whether a new ovarian stimulation protocol termed "minimal stimulation" provides pregnancy rates (PRs) comparable with those in a conventional full stimulation protocol for patients undergoing assisted reproductive technologies (ART).

DESIGN

Prospective, nonrandomized study of patients in minimal stimulation or full stimulation, followed by standard IVF and zygote intrafallopian transfer or uterine-ET.

SETTING

The ART program of the Mayo Clinic, Rochester, Minnesota.

PATIENTS

Women (n = 120) 42 years of age or younger with serum day 3 FSH level < or = 15.0 mIU/mL (conversion factor to SI unit, 1.0), normal thyroid-stimulating hormone and PRL levels, normal endometrial cavity as observed on hysterosalpingogram, and partners with a normal semen analysis.

INTERVENTIONS

Oral clomiphene citrate, hMG, oocyte retrieval, IVF-ET.

MAIN OUTCOME MEASURES

Cancellations, implantation, pregnancy.

RESULTS

The cancellation rate was not significantly higher in minimal stimulation (25.8%) than in full stimulation (14.1%). Minimal stimulation cycles yielded fewer oocytes per aspiration (3.4 +/- 1.6) than full stimulation (10.1 +/- 5.4). There was no difference in the implantation rates per ET (minimal stimulation, 16.4%; full stimulation, 13.3%) or overall clinical PRs per retrieval (minimal stimulation, 31%; full stimulation, 42%).

CONCLUSIONS

Minimal stimulation for IVF is less expensive than full stimulation and minimizes monitoring and patient discomfort. In addition, it produces acceptable PRs and represents an attractive alternative to select patients undergoing ART.

Early, late, and sequential embryo transfer in in vitro fertilization program: a preliminary report

The timing of ET was evaluated by transferring four embryos at 44 to 48 hours, 68 to 72 hours, or equally dividing and sequentially transferring at 44 to 48 and 68 to 72 hours after insemination. Fifty-one patients were randomly allocated to one of the above protocols. The mean number of blastomeres of embryos transferred at 68 to 72 hours after insemination was significantly (P less than 0.0001) higher than those transferred at 44 to 48 hours. The number of embryos with good morphology was similar in all study groups. The pregnancy rate was similar in the three protocol groups, 53% at 44 to 48 hours, 59% at 64 to 72 hours, and 47% by sequential transfer. There probably is no advantage in delaying the transfer or dividing the embryos into two sequential transfers. It seems that sequential transfer is not associated with any harmful effect.

Improvements in ovarian stimulation for in vitro fertilization

What are the major improvements in stimulation over recent years? The stimulated cycle has completely superseded the natural cycle since this is the only method of obtaining several embryos. In conventional stimulation, despite an enormous body of literature, no single treatment modality has emerged as superior to other forms of therapy. Undoubtedly it is the experience and habits of individual IVF teams that determine the success of one or another method. Therefore programmed stimulation is an improvement in that it introduces the factors of convenience and simplicity while retaining the clinical efficacy of stimulation by conventional treatment. The analogues of LHRH are still in an early phase of development, but they appear to be associated with a low cancellation rate even in previous poor-responders. Furthermore, preliminary results seem to indicate that this is the first development since the widespread adoption of follicular stimulation, which is associated with an increased pregnancy rate. We are currently involved in trying to associate programmed stimulation and analogue treatment in a bid to combine the advantages of both therapies. Finally, embryo cryopreservation must be mentioned. There is no point in refining our stimulation protocols to obtain many embryos if those surplus to immediate requirement are disposed of. Cryopreservation offers the means of maximizing the pregnancy potential of a single IVF cycle while reducing the possibility of multiple pregnancy.

The effect of fibrin sealant on mouse embryos

It is postulated that ovarian hyperstimulation prior to embryo transfer results in changes in the endometrium which lead to poor adhesive properties of the endometrium. Based on the properties of fibrin sealant which is used in human operative medicine, it is believed that adhesion of embryos to the endometrium during embryo transfer may be encouraged by the addition of fibrin sealant. The purpose of this study was to assess the effects of the addition of fibrin sealant to a mouse embryo/Ham's F-10 culture medium mixture. There was no statistical difference in the number of blastocysts developing from 138 embryos in standard medium compared with 139 cultured with the addition of fibrin sealant. It is concluded that fibrin sealant is not embryotoxic, and thus following further experimentation its eventual utilization in human in vitro fertilization/embryo transfer programs appears promising.

Gonadotropins augment maturation and fertilization of human immature oocytes cultured in vitro

The inclusion of hMG in the culture medium for immature human oocytes results in improved maturation and fertilization rates. The resulting increased number of conceptuses available for transfer may improve the incidence of IVF pregnancy.

Endocrine changes in the late-follicular and postovulatory intervals as determinants of the in vitro fertilization pregnancy rate

This investigation examines the hormone pattern in in vitro fertilization (IVF) cycles from the time of human chorionic gonadotropin (hCG) administration through embryo transfer to ascertain whether the absolute levels or secretory patterns of the major reproductive hormones affect the IVF pregnancy rate. Thirty-one women who underwent IVF treatment were enrolled in the study. All patients received clomiphene citrate/human menopausal gonadotropin for ovulation induction. Significant elevations in serum estradiol (E2) levels in the pregnant group were found throughout the cycle interval studied. After hCG administration the serum hCG levels were not different between the groups. Significant elevations in serum progesterone (P) concentrations were found in the pregnant group from the day after laparoscopy through embryo transfer. Embryos obtained from the pregnant group appeared to be different in that the mean number of blastomeres per embryo transferred was significantly greater. Therefore for achievement of an IVF pregnancy the optimal hormone pattern employing combination ovulation induction in the ovulation to transfer interval is a relatively high E2 level in ovulation followed by a high P level at transfer and into the luteal phase. These elevated hormone levels do not depend on the response to exogenous hCG.