The effect of withholding gonadotropin (a coasting period) on the outcome of in vitro fertilization cycles

Is Coasting Valuable in All Patients with Any Cause of Infertility?

OBJECTIVES

This study aimed to assess the influence of coasting duration on the number and quality of oocytes and fertilization rate in male factor infertile women and those with polycystic ovary syndrome (PCOS).

METHODS

In this prospective observational follow-up study, 114 patients undergoing coasting (53 women with male factor infertility and 61 women with PCOS) were evaluated at the Royan Institute Research Center, Iran, between 2010 and 2012.

RESULTS

The results were analyzed according to the coasting periods of 1-4 days. In normal females, the number of oocytes retrieved was significantly reduced after the second day (p = 0.004). In addition, a statistically significant drop was observed in the number of metaphase II oocytes and fertilization rate after the third day (p = 0.006 and p = 0.006, respectively). No significant differences were observed in the number and quality of oocytes retrieved and fertilization rate with regard to coasting days in PCOS patients.

CONCLUSION

Coasting with duration of more than three days should be performed with caution in normal females who are at risk of developing ovarian hyperstimulation syndrome.

Does the serum E2 level change following coasting treatment strategy to prevent ovarian hyperstimulation syndrome impact cycle outcomes during controlled ovarian hyperstimulation and in vitro fertilization procedure?

OBJECTIVE

Ovarian hyperstimulation syndrome (OHSS) remains as a clinical problem for hyperresponder patients during controlled ovarian hyperstimulation and in vitro fertilization (COH-IVF) procedure. Herein, we aimed to evaluate the COH-IVF outcomes in hyperresponder patients managed with coasting treatment strategy for OHSS prevention regarding the establishment of clinical pregnancy as an endpoint of the treatment cycle.

MATERIALS AND METHODS

The medical records related to the COH-IVF outcome in 119 hyperresponder patients who have exhibited a serum estradiol level greater than or equal to 3000 pg/mL were evaluated. The study was conducted on a total of 119 patients, 98 of whom have been treated by coasting or coasting with GnRH antagonist co-treatment strategies, while the remaining 21 women (control group) have not been managed with coasting treatment. The COH and IVF-ET outcomes in the 119 patients were compared based on the coasting treatment situation.

RESULTS

Among the women who received coasting treatment, the number of patients demonstrating E2 level decrement and also E2 level decrement rate after coasting were similar between patients with and without clinical pregnancy. Total gonadotropin dose, 2PN number, embryo number, and fertilization rate were significantly higher in the patients with a clinical pregnancy.

CONCLUSION

The coasting treatment is a clinically useful preventive strategy for OHSS avoidance. GnRH antagonist co-treatment decreases the duration of coasting although any detrimental or ameliorating impact of this effect on pregnancy rates have not been seen. The E2 level decrement or increment following coasting treatment seems not to be related to cycle outcomes.

Effect of coasting on IVF cycle characteristics and outcome in short vs. long GnRH agonist protocols

AIMS

To compare the results of IVF cycles following coasting in patients treated with long versus short GnRH agonist protocols.

METHODS

A retrospective comparative study in which all women aged 35 years or less attending the IVF unit from 2000 to 2006 in whom coasting was used in GnRH agonist protocols were included. Data on coasting-related variables and outcome were collected from the files and compared between the short GnRH agonist (n = 78) and long GnRH agonist (n = 181) cycles.

RESULTS

The short GnRH agonist cycles were characterized by higher E2 levels during coasting and longer duration of coasting than the long GnRH agonist cycles. Although the number of retrieved oocytes was lower following coasting in the short protocol, there was no difference between the groups in fertilization rate, number of high-quality embryos available for transfer, and pregnancy rate. Pregnancy rate in both protocols was negatively correlated to E2 level at initiation of coasting. The overall moderate and severe OHSS rate after coasting was 5.1% in the short-protocol group and 6.0% in the long-protocol group (p = 0.76).

CONCLUSIONS

The ovarian response curve to coasting is longer in the short than in the long GnRH-agonist protocol, but there is no significant difference in pregnancy or OHSS rates.

A unique human chorionic gonadotropin antagonist suppresses ovarian hyperstimulation syndrome in rats

Ovarian hyperstimulation syndrome (OHSS) is a complication of in vitro fertilization associated with physiological changes after hCG administration to induce final oocyte maturation. It presents as widespread increases in vascular permeability and, in rare cases, results in cycle cancellation, multi-organ dysfunction, and pregnancy termination. These physiological changes are due primarily to activation of the vascular endothelial growth factor (VEGF) system in response to exogenous human chorionic gonadotropin (hCG). An hCG antagonist (hCG-Ant) could attenuate these effects by competitively binding to the LH/CG receptor, thereby blocking LH activity in vivo. We expressed a form of hCG that lacks three of its four N-linked glycosylation sites and tested its efficacy as an antagonist. The hCG-Ant binds the LH receptor with an affinity similar to native hCG and inhibits cAMP response in vitro. In a rat model for ovarian stimulation, hCG-Ant dramatically reduces ovulation and steroid hormone production. In a well-established rat OHSS model, vascular permeability and vascular endothelial growth factor (VEGF) expression are dramatically reduced after hCG-Ant treatment. Finally, hCG-Ant does not appear to alter blastocyst development when given after hCG in mice. These studies demonstrate that removing specific glycosylation sites on native hCG can produce an hCG-Ant that is capable of binding without activating the LH receptor and blocking the actions of hCG. Thus hCG-Ant will be investigated as a potential therapy for OHSS.