Preparation of endometrium for egg donation.

Nowadays oocyte donation is a well established method of assisted reproduction and offers the unique opportunity to treat patients with various clinical indications, with or without ovarian function, in a novel way. In women with ovarian failure, artificial menstrual cycles are required before proceeding to oocyte donation. Oestrogen may be delivered in the form of oral tablets, transdermal patches in order to bypass the gastrointestinal tract thus avoiding first pass metabolism and by vaginal application. Our regimen is oestradiol valerate given in various concentrations, in order to mimic the regular cyclic fluctuations throughout the cycle. Progesterone may be administered in the form of oral tablets, intravaginal suppositories or rings and i.m. injections. Our results, as of most other groups, strongly support the vaginal route of progesterone administration. In women with retained ovarian function, synchronization of donor-recipient cycle presents a special problem, as there is strong evidence that a temporal window of maximal endometrial receptivity exists. Cryopreservation of donated embryos may be used to overcome the problem, but this approach has the important drawback of embryonic loss occurring after freezing and thawing. The method of choice is the administration of gonadotrophin-releasing hormone agonists (GnRHa) to render the patients functionally agonadal in order to circumvent cycle asynchrony between the donor and recipient.