Effect of Endometrial Injury Before Frozen Embryo Transfer on Pregnancy Rate

Suitable women will be invited to participate in the study then a signed and informed consent will be obtained from them. When the patient's consent is obtained, they are to be included into the study.

Data Collection:

During first visit, all patients will undergo complete clinical examination and detailed medical history will be obtained. Each patient will have a Case Record Form (CRF) in which the following data will be recorded.

• Patient number (according to the randomization schedule).
• Age, BMI.
• Past medical and surgical history.
• Duration of infertility.

Procedure:

Endometrial injury:

A single induced injury will be done on the posterior endometrium on day 7 of the transfer cycle by using modified Cook catheter Protocol for vitrification Embryos will first loaded with equilibrium solution containing7.5% ethylene glycol (EG) and 7.5% dimethyl sulphoxide (DSMO) (Sigma-Aldrich) for 5-10 minute at room temperature and then with vitrification solution containing 15% EG, 15% DSMO and 0.5 mol/L sucrose for 50-60 seconds at room temperature. After observed cellular shrinkage, embryos will quickly stored in liquid nitrogen (LN) for at least 2 months. At warming, embryos will removed from LN and embryos will exposed to thawing solution containing sucrose at 37°C temperature for 50-60 seconds and then embryos will sequentially incubated in diluents solutions before being transferred .

Evaluation and transfer of thawed embryos After thawing, each embryo will evaluated twice, once immediately for the number of surviving blastomeres and again after 18 hours post-thaw in vitro culture for assessing of mitosis and number of blastomeres. Embryos will considered survived if >50% of each blastomere are intact and selected for intrauterine transfer (Depending on patients' embryos, 2 or 3 embryos will transferred).

Embryos will classified as fully intact or excellent morphology (100% cells survived with \<10% fragmentation) or good morphology (100% cells survived with 10%-20% fragmentation), partially damaged or poor morphology (≥50% cells survived with or without any fragmentation) and Degenerated embryos (\<50% cells survived) .Only fully intact and partially damaged embryos will transferred. Degenerated or arrested embryos will not transferred.

Protocol of endometrial preparation before Frozen Embryo Transfer (FET) :

There are different protocols for FET cycles. That is true for both "natural cycle" FETs and for "hormone replacement cycle" frozen-thawed embryo transfers. We will use hormone replacement cycles because they have better success rates. However, some clinics offer a natural cycle FET approach. Success rates are higher with hormone replacement, or "controlled" FET cycles.

Medicines and Drugs in a Frozen Embryo Transfer FET Cycle

1. Gonadotropin-Releasing Hormone agonist (such as Lupron) will be given, either midluteal (day 21) or overlapping with a birth control pill.
2. Down-regulation will be confirmed by ultrasound and blood tests.
3. Estradiol valerate 2 mg twice daily (orally) will start after the period. This dose may need to be increased after monitoring of the uterine lining thickness.
4. When the endometrium has a "good" thickness( > 8 mm), progesterone will be started (intramuscular shots, or a vaginal product).
5. Embryo transfer will be planned for 3-6 days later - depending on the stage of development of the embryos to be transferred.
6. Estrogen and progesterone will be continued in the luteal phase.
7. Pregnancy testing will be done 9-14 days after transfer - depending on the stage of development of the embryos replaced and the preferences of the fertility clinic.
8. If pregnant, estrogen and progesterone will be continued until about 10-15 weeks of pregnancy and then weaned off.