Letter to the Editor |
‘Enhancement of embryo developmental potential by a single administration of GnRH agonist at the time of implantation’
Lifequest Centre for Reproductive Medicine, Toronto, Canada M5G 2K4
E-mail: drhannam{at}fertility.ca
Jan Tesarik et al. (2004)
set out to improve the implantation rate (IR) in their donor oocyte programme by giving recipients in the study group a single injection of a short-acting GnRH agonist (triptorelin 0.1 mg s.c.) on day 6 following a day 3 embryo transfer in the recipient patient. Their IR increased to 36.9% compared to 25.1% in the control group (P < 0.05).
Perhaps such results should not have been surprising. GnRH agonists are well known to stimulate placental HCG production both in vivo and in vitro, and the authors note that preimplantation mouse embryos express GnRH receptor mRNA.
Based on this study, I have introduced a pilot programme into my practice, administering buserelin 0.2 mg s.c. on day 6 following day 3 or 5 embryo transfers in otherwise traditional IVF cycles. Ovarian hyperstimulation syndrome (OHSS) is usually a rare outcome in my practice, yet frequently patients now complain of early symptoms following the buserelin. Recently, we diagnosed our first severe OHSS in an at-risk patient. She had actually been doing well, until a few hours after the buserelin injection, when symptoms arose (and, 48 h later, completely resolved). I cannot, of course, prove causality.
Is luteal GnRH agonist therapy ready for clinical practice? A cautious approach is warranted. It was not that long ago that luteal HCG supplementation held extraordinary promise, yet today its efficacy is considered questionable in many circumstances (Daya and Gunby, 2004). The comparison is made because the two substances may be expected to have similar function on the corpus luteum. By design, Tesarik et al.’s study could not have revealed such activity.
A recent study in sheep compared GnRH agonist to HCG administration in the luteal phase, noting comparable results (with HCG demonstrating a slightly higher delivery rate) (Akif Cam and Kuran, 2004). As Tesarik et al. note, further studies will be needed with the GnRH agonists to confirm efficacy and safety across a range of clinical scenarios. However, based on my anecdotal evidence, I would look for an increase in the incidence of OHSS in many patient subgroups.
References
Akif Cam M and Kuran M (2004) Effects of a single injection of hCG or GnRH agonist on day 12 post mating on fetal growth and reproductive performance of sheep. Anim Reprod Sci 80,81–90.[CrossRef][Medline]
Daya S and Gunby J (2004) Luteal phase support in assisted reproduction cycles. Cochrane Database Syst Rev (3):CD004830.
Tesarik et al (2004) Enhancement of embryo developmental potential by a single administration of GnRH agonist at the time of implantation. Hum Reprod 19,1176–1180.
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