Effectiveness of two-step (consecutive) embryo transfer in patients who have two embryos on day 2: comparison with cleavage-stage embryo transfer.

ABSTRACT

OBJECTIVE: To evaluate the effectiveness, for patients who have only two embryos on day 2, of a two-step (consecutive) embryo transfer (ET) procedure in which a cleaved embryo is transferred on day 2 and a single blastocyst is transferred on day 5. DESIGN: Observational comparative study. SETTING: Private IVF clinic. PATIENT(S) Ninety two-step ET cycles were performed in patients who had two embryos on day 2 (two-step group). Ninety day-2 ET cycles were performed in age- and infertility-matched patients who had two embryos on day 2 (control group). INTERVENTION(S) Cleaved-ET, extended culture of one embryo, and a second transfer of a blastocyst. MAIN OUTCOME MEASURE(S) Implantation and pregnancy rates. RESULT(S) The pregnancy and implantation rates in the two-step group (respectively 33.3% and 17.2%) were significantly higher than those in the control group (18.9% and 9.4%). Thirty-nine of the patients in the two-step group (43.3%) could not proceed to the second step of ET because no viable blastocyst could be obtained, but four of them conceived anyway. CONCLUSION(S) Taking advantage of both day-2 ET and blastocyst transfer, two-step ET may be an effective option for ET in patients who have an insufficient number of embryos.