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Hamster respiratory epithelial cells were cultured in a monolayer format, and 20% of the cells were ciliated. Mycoplasma pneumoniae attached to the epithelial cells in a neuraminidase-specific fashion and induced ciliostasis and cytonecrosis.

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BACKGROUND: Trophectoderm biopsy for preimplantation genetic screening (PGS) is more commonly performed on fresh blastocysts following oocyte retrieval, however situations arise where patients desire PGS testing on previously vitrified blastocysts. The effect of two cryopreservation/thawing procedures prior to euploid blastocyst transfer is largely unknown and previous data is limited by small numbers (1).OBJECTIVE: To compare survival rates and pregnancy outcomes of euploid blastocysts that underwent two cryopreservation/thaw cycles to the standard of one freeze/thaw cycle prior to embryo transfer.MATERIALS AND METHODS: All women who underwent a euploid frozen embryo transfer (FET) following PGS testing for aneuploidy from 6/2013-6/2017 were included for analysis. 125 FET cycles that underwent two vitrification/thaw cycles (PGS study group) were compared to 1,028 FET cycles that underwent one vitrification/thaw cycle (PGS control group). We excluded cycles that only performed PGD for single gene disorders and patients that required repeat trophectoderm biopsy due to inconclusive results. Primary outcome measures included pots thaw survival rates, implantation, clinical pregnancy and ongoing pregnancy rates. Outcomes were also stratified by blastocyst morphology excellent (R3AA); good (3-6AB, 3-6BA, 1-2AA); average (3-6BB, 3-6AC, 3-6CA, 1-2AB, 1-2BA); poor (1-6BC, 1-6CB, 1-6CC, 1-2BB).RESULT(S): The reasons for performing trophectoderm biopsy on previously vitrified, untested blastocysts in the study group were interim pregnancy loss (54%), gender selection (24%), previous unsuccessful cycle (17%), and single gene disorder testing with PGD/PGS(6%). Demographic characteristics showed that the PGS study group (2 freeze/thaw cycles) were significantly younger (mean age 34.4 vs. 36.3, p<0.0001) and had a higher gravidity, parity and # of prior IVF cycles compared the PGS control group (1 freeze/thaw cycle). There were no differences in peak endometrial thickness, % Natural FET cycles, and # of embryos transferred (1.1AE0.4 vs. 1.2AE0.4) between groups. There was no difference in survival rates post thaw (96.0% vs. 97.9%, p¼0.15), regardless of blastocyst morphology. The PGS study group demonstrated statistically lower clinical pregnancy (48.8% vs. 58.9%, p¼0.03) and ongoing pregnancy rates (40.8% vs. 55.7%, p¼0.002) compared to the control group. They also showed a lower implantation rate that trended toward, but did not reach significance (p¼0.07). When stratifying by blastocyst morphology, only blastocysts in the PGS study group with average-poor morphology showed a lower ongoing pregnancy rate (41.6% vs. 54.4%, p¼0.01). There was no difference in pregnancy outcomes in the good-excellent blastocyst morphology group, regardless of number of freeze/thaw cycles. CONCLUSION(S): Multiple vitrification/thaw cycles do not decrease the post thaw survival rates of blastocysts. However, the number of freeze/thaw cycles may be a previously unidentified factor that negatively affects the implantation and pregnancy potential of...