title: Blastocyst culture: facts and fiction.
abstract: The use of sequential media has made extended culture and transfer of blastocysts feasible for human IVF. Embryo transfer on day 5 has been claimed to result in higher implantation rates than transfer on day 3, on the basis of retrospective comparative studies. This is not supported convincingly, however, in randomized controlled trials published to date. Blastocyst culture imposes additional requirements in terms of personnel, equipment, education and cost and is associated with a greater incidence of monozygotic twinning and cycle cancellation rate than in the case of day 3 culture. In order for day 5 transfer to replace day 3 transfer, a convincing comparison between the two methods should therefore demonstrate the superiority of blastocyst transfer. There is still a need for properly designed randomized controlled trials to compare day 3 with day 5 transfer which will also address the effectiveness of a single blastocyst replacement in reducing the incidence of multiple pregnancies as well as the value of blastocyst cryopreservation.
authors.affiliation: Centre for Reproductive Medicine, Dutch-Speaking Free University of Brussels, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: Efstratios M
authors.initials: EM
authors.lastname: Kolibianakis
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology*; D015925:Cryopreservation; D046508:Culture Techniques / Q000379:methods; D004624:Embryo Transfer; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011272:Pregnancy, Multiple; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors; D014430:Twins, Monozygotic