Value of transferring embryos that show no evidence of fertilization at the time of fertilization assessment

Capsule:
Transfer of nonpronuclear (0PN) embryos results in pregnancies and live births. Blastocyst cultures can provide a better way to select normal 0PN embryos for transfer and thus achieve satisfactory outcomes.

Authors:
Ming Li, M.S., Shengli Lin, M.D., Yuan Chen, M.D., Jinliang Zhu, M.D., Ping Liu, M.D., Jie Qiao, M.D.

Volume 104, Issue 3, Pages 607-611

Abstract:

Objective:
To determine the value of transferring embryos formed from nonpronuclear (0PN) zygotes.

Design:
A case-control study.

Setting:
Not applicable.

Patient(s):
The current study was a retrospective analysis of embryo transfers of just 0PN embryos using fresh cleavage-stage embryos (0PN cleavage fresh), frozen-thawed cleavage-stage 0PN embryos (0PN cleavage frozen), and frozen 0PN blastocyst-stage embryos (0PN blast frozen).

Intervention(s):
To study the effect of 0PN transfer, comparison groups were used: fresh cycles of 2PN (2PN cleavage fresh-C) and frozen-thawed cycles cleavage-stage (2PN cleavage frozen-C) and blastocyst-stage (2PN blast frozen-C). Comparison groups were matched for cycle and patient characteristics to the 0PN group.

Main Outcome Measure(s):
Implantation rate (IR), pregnancy rate, and transferable embryo rate.

Result(s):
For fresh cycles, the IR in the 0PN cleavage fresh was lower than that in the 2PN cleavage fresh-C (8.04% vs. 19.50%, respectively). For frozen-thawed cycles, the IR in the 0PN cleavage frozen was lower than that in the 2PN cleavage frozen-C (15.38% vs. 28.24%, respectively), but the IR in 0PN blast frozen was comparable to that of 2PN blast frozen-C (39.56% vs. 48.18%, respectively).

Conclusion(s):
Transfer of 0PN embryos from fresh or frozen-thawed cycles results in pregnancies and live births. Nonpronuclear embryos have a lower IR than 2PN embryos, but if the embryos are cultured to the blastocyst stage and then are frozen, their IRs approach that of 2PN embryos in subsequent frozen-thawed cycles. The culture of 0PN embryos to the blastocyst stage may select for embryos with a near-normal IR.

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