title: Large-volume vitrification of human biopsied and non-biopsied blastocysts: a simple, robust technique for cryopreservation.
abstract: OBJECTIVE
  To evaluate the transition from a proven slow-cooling cryopreservation method to a commercial large-volume vitrification system for human blastocysts.
  
  
  METHODS
  Retrospective analysis of de-identified laboratory and clinical data from January 2012 to present date for all frozen embryo replacement (FET) cycles was undertaken. Cryopreservation of trophectoderm-biopsied or non-biopsied blastocysts utilized during this time period was logged as either slow-cooling, small-volume vitrification, or large-volume vitrification. Blastocyst survival post-warm or post-thaw, clinical pregnancy following FET, and implantation rates were identified for each respective cryopreservation method.
  
  
  RESULTS
  Embryo survival was highest for large-volume vitrification compared to micro-volume vitrification and slow-cooling; 187/193 (96.9 %), 27/32 (84.4 %), and 244/272 (89.7 %), respectively. Survival of biopsied and non-biopsied blastocysts vitrified using the large-volume system was 105/109 (96.3 %) and 82/84 (97.6 %), respectively. Survival for micro-volume biopsied and non-biopsied blastocysts was 16/30 (83.3 %) and 2/2 (100.0 %) respectively. Slow-cooling post-thaw embryo survival was 272/244 (89.7 %). Clinical pregnancy and implantation rates outcomes for non-biopsied embryos were similar between large-volume and slow-cooling cryopreservation methods, 18/39 (46.2 %) clinical pregnancy and 24/82 (29.3 %) implantation/embryo, and 52/116 (44.8 %) clinical pregnancy and 67/244 (27.5 %) implantation/embryo, respectively. Comparing outcomes for biopsied embryos, clinical pregnancy and implantation rates were 39/67 (58.2 %) clinical pregnancy and 50/105 (47.6 %) implantation/embryo and 4/16 (25 %) clinical pregnancy and 6/25 (24.0 %) implantation/embryo, respectively.
  
  
  CONCLUSIONS
  The LifeGlobal large-volume vitrification system proved to be very reliable, simple to learn and implement in the laboratory. Clinically large-volume vitrification was as, or more effective compared to slow-cooling cryopreservation in terms of recovery of viable embryos in this laboratory.
authors.affiliation: Center for Reproductive Medicine of New Mexico, 201 Cedar Street SE, Suite S1-20, Albuquerque, NM, 87106, USA, mleroyreed@gmail.com.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Reed
authors.forename: Al-Hasen
authors.initials: AH
authors.lastname: Said
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Thompson
authors.forename: Charles L
authors.initials: CL
authors.lastname: Caperton
mesh_terms: D000328:Adult; D001706:Biopsy; D001755:Blastocyst / Q000502:physiology*; D015925:Cryopreservation / Q000379:methods*; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D058989:Vitrification