Is there any benefit from the culture of a single oocyte to a blastocyst-stage embryo in unstimulated cycles?
BACKGROUND
The aim of the study was to test the influence of 2- and 5-day cultivation of a single oocyte on the pregnancy rate in a non-stimulated cycle.


METHODS
A retrospective chart review of 391 consecutive patients undergoing IVF and intracytoplasmic sperm injection in unstimulated cycles was performed. The embryos were kept in MediCult universal IVF medium for day 2 transfers and in BlastAssist System for day 5 transfers.


RESULTS
The oocyte recovery rate in the group for 2-day cultivation and in the group for 5-day cultivation was similar, being 79.4 (162/204) and 83.6% (154/187) respectively. The same is true of the fertilization rate (73.8 versus 77.7%). The blastulation rate was 52.8%. The embryo transfer rate per cycle was higher when day 2 embryos were transferred: 64.8% (105/162) compared with 35.7% (55/154) if blastocyst-stage embryos were transferred. The pregnancy rate per transferred embryo was higher when a blastocyst was transferred (40.0%) instead of a day 2 embryo (23.8%).


CONCLUSIONS
The expected pregnancy rate calculated per embryo available on day 2 of cultivation was similar in both groups (23.8 versus 22.2%) and it was not affected by oocyte culture to the blastocyst stage.
Vlaisavljević
V
V
Department of Reproductive Medicine and Gynaecologic Endocrinology, Maribor Teaching Hospital, Ljubljanska 5, SI 2000 Maribor, Slovenia. vlai@sb-mb.si
Kovacic
B
B
Reljic
M
M
Lovrec
V G
VG
Sajko
M C
MC
D001755:Blastocyst / Q000502:physiology*; D003470:Culture Media; D046508:Culture Techniques; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D009865:Oocytes / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors
D003470:Culture Media