High Pregnancy Rate in “Abandoned” Blastocyst Cycles

Abstract

Objectives: The ability of ART laboratories to grow embryos to the blastocyst stage in vitro has increased the chance that viable embryos will be selected and therefore reduced the need to transfer more than 2–3 embryos. However, it is not clear 3 days after oocyte retrieval, when most early stage embryo transfers are performed, which, if any, embryos will develop to the blastocyst stage by Day 5. The objective of this study was to determine if advanced embryo cell number on Day 3 was predictive of blastocyst development and increased pregnancy rates. Design: A retrospective review of 77 ART cycles from January 1999 through January 2000 was performed. All patients had desired development of their embryos to the blastocyst stage prior to transfer. Materials and Methods: We decided to use the presence of at least 3 embryos at the ≥8-cell stage on the morning of Day 3 as the minimum requirement for continuation of the blastocyst cycle to Day 5 in our patients. Embryo quality on Day 3 was not a criterion for deciding whether patient cycles were continued to the blastocyst stage in vitro prior to embryo transfer. Patients in whom the blastocyst cycle was “abandoned” on Day 3 had their embryos transferred on Day 3 after assisted hatching. A regimen of sequential media was utilized to optimize embryo growth to the blastocyst stage. Statistical analysis was performed using a t-test and chi-square analysis. Results: The results of this study are presented in the table below. Despite a similar average age in both groups, the patients in B group had more oocytes retrieved (14.7 vs. 10.5) and more embryos to choose from on Day 3 (9.8 vs. 4.9) than those in the D3 group. In the D3 group, 43/45 patients had an embryo transfer and the mean # of cells in the transferred embryos was 5.3 cells. In the B group, 31/32 (97%) patients had a transfer on Day 5, although only 23/31 (74%) had 1 or more actual blastocysts at the time of transfer. The remaining 8 patients had embryos only at the early cavitation stage when transferred. Nevertheless, 2 pregnancies occurred in these 8 patients. ∗Group#Age# Eggs# Embryos Day 3# Cells Day 3# Trans- ferred(+) hCGClinical pregnanciesBlastocyst (B)3236.314.7∗p<0.5 vs. D3.9.8∗p<0.5 vs. D3.6.5∗p<0.5 vs. D3.1.615 (46.8%)12 (37.5%)Day 3 (D3)4536.210.54.95.34.318 (40%)17 (37.8%)∗ p<0.5 vs. D3. Open table in a new tab Conclusions: (1) Patients without multiple embryos at or beyond the 8-cell stage on the morning of Day 3 still have a good prognosis for clinical pregnancy when Day 3 embryo transfer is performed after assisted hatching. (2) The presence of at least 3 embryos at or beyond the 8-cell stage on Day 3 results in a high percentage of patients having at least 1 blastocyst to transfer and good pregnancy rates. (3) Clinical pregnancies can occur in patients who have no embryos at the blastocyst stage on Day 5. (4) Patients without multiple embryos at advanced cell stages on Day 3 may benefit more from early transfer with assisted hatching rather than continued growth to the blastocyst stage.