title: Should a single blastocyst transfer policy be a clinical decision or should it depend on the embryological evaluation on day 3?
abstract: BACKGROUND
  Single blastocyst transfer has the advantage of maximizing the fresh single pregnancy rate. However, in patients with a low number of good quality embryos on day 3, it remains unclear whether immediate embryo transfer or further embryo culture with blastocyst transfer is the most preferable option.
  
  
  METHODS
  A retrospective cohort study was carried out in which the outcome of 590 fresh in vitro fertilization (IVF) cycles over a 15 months period and their cryo cycles were analyzed. A total of 341 patients cycles had an elective day 5 strategy independent of intermediate embryo evaluation while another 249 patients underwent a day 5 embryo transfer only if at least four embryos were available on day 3. Blastocyst vitrification was performed using a closed high security system.
  
  
  RESULTS
  Demographics, stimulation parameters and embryological data were comparable in the two groups. Patients in the elective day 5 group had a lower fresh transfer rate (90.62% vs. 95.18%, p < 0.05) as compared to patients with a day 3 or day 5 embryo transfer policy. No difference was observed in the fresh live birth rate and multiple pregnancy rate per initiated cycle (32.84% vs. 28.92%; 1.17% vs 0%) The projected cumulative ongoing pregnancy rate compensating for double counting in case subjects have more than one pregnancy is not different (42.58% vs. 39.84%).
  
  
  CONCLUSIONS
  Despite lower fresh transfer rates, elective single blastocyst transfer yields a similar projected cumulative ongoing pregnancy rate as in a policy with cleavage stage or blastocyst transfer depending on a good quality embryo count on day 3.
authors.affiliation: Centre for Reproductive Medicine, University Hospital, Vrije Universiteit Brussel (Free University of Brussels), Brussels, Belgium. dominic.stoop@uzbrussel.be
authors.forename: Dominic
authors.initials: D
authors.lastname: Stoop
authors.forename: Lisbet
authors.initials: L
authors.lastname: Van Landuyt
authors.forename: Etienne
authors.initials: E
authors.lastname: Van den Abbeel
authors.forename: Michel
authors.initials: M
authors.lastname: Camus
authors.forename: Greta
authors.initials: G
authors.lastname: Verheyen
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
mesh_terms: D000328:Adult; D002970:Cleavage Stage, Ovum / Q000166:cytology; D015331:Cohort Studies; D003657:Decision Making / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods*; D004622:Embryo, Mammalian / Q000166:cytology*; D005260:Female; D005307:Fertilization in Vitro / Q000331:legislation & jurisprudence*; D006801:Humans; D008297:Male; D057766:Policy; D011247:Pregnancy; D018873:Pregnancy Rate; D011786:Quality Control; D012189:Retrospective Studies; D013997:Time Factors