الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Slowly developing embryos in IVF cycles are considered to be a quite challenging issue. Effect of reculturing of slowly developing embryos has shown that it can effectively help the embryos to reach a more advance stage in vitro before ET. However, it is still uncertain whether the day of blastocyst formation influences clinical outcomes.
Numerous studies have evaluated the outcomes of FET cycles with blastocysts. According to some reports, blastocysts formed and cryopreserved on day 5 (D5 blastocysts) and day 6 (D6 blastocysts) had similar outcomes. However, other studies showed that the CPR, IR, and live birth rate (LBR) are higher with D5 blastocysts than with D6 blastocysts.
The study was conducted aiming to evaluate the effectiveness of reculturing of thawed slowly developing embryos before transfer on implantation and pregnancy.
The study was conducted on 60 females undergoing FET using slowly developing embryos. Patients were randomized to either group I or group II. Embryos for patients in group I were thawed on the 5th day of progesterone supplementation. After warming, the embryos will be cultured in the incubator for 24 hours. The embryos are checked and reassessed on the day of embryo transfer (6th day of progesterone supplementation) followed by embryo transfer. Patients in group II had a same day embryo transfer.
The primary outcome will be the positive pregnancy test rate and implantation rate and the secondary outcome is ongoing pregnancy rate. Our results showed no difference in positive BHCG test rate , implantation rate (17% in group I, 16% in group II) and ongoing pregnancy rates (16% in group I, 15% in group II) between 2 groups per FET cycle.
However, when comparing implantation and ongoing pregnancy rates between group I and II in terms of embryos transferred, we found significant improvement in group I compared to group II (implantation rate: 19 gestational sacs out of 54 embryos transferred; 35.2% in group I versus 16 sacs out of 83 embryos transferred; 19.3% in group II, P value = 0.037, and ongoing pregnancy rate: 25.9% in group I versus 12% in group II, P value = 0.037).
We concluded that reculturing slowly developing embryos have a promising potential to improve embryo stage of development before ET and the clinical outcome of FET cycles. More studies with bigger sample sizes are needed.