title: Potential risk of monochorionic dizygotic twin blastocyst formation associated with early laser zona dissection of group cultured embryos.
abstract: OBJECTIVE
  To document the risk of in vitro monochorionic dizygotic twin formation in the implementation of a program of blastocyst biopsy with preimplantation genetic screening (PGS).
  
  
  METHODS
  Case report.
  
  
  METHODS
  Private infertility laboratory.
  
  
  METHODS
  Prospective PGS patients with intracytoplasmic sperm injection-derived, group-cultured blastocysts over a 3-year period.
  
  
  METHODS
  Group culture in Global medium (Life Global) to optimize blastocyst formation of zygotes produced for blastocyst biopsy for PGS (n ≤ 8 embryos/25 μL droplet), and laser zona dissection (LZD) of all day-3 cleaved embryos to promote pre-expansion trophectodermal extrusion at the blastocyst stage (i.e., premature hatching).
  
  
  METHODS
  Blastocyst formation and quality grading on days 5 and 6 of in vitro culture for the vitrified embryo transfer of single or dual euploid blastocysts.
  
  
  RESULTS
  Over 3,000 blastocysts were produced in vitro. On two separate occasions, complete trophectodermal amalgamation was observed between two hatching blastocysts. Vitrified single-euploid blastocyst transfers efficiently implanted and established clinical pregnancies similar to dual-euploid blastocyst transfers, without the risk of twin formation.
  
  
  CONCLUSIONS
  The amazing occurrence of monochorionic dizygotic twin formation has now been documented in vitro, supporting the theory that assisted reproductive technology may facilitate this rare perinatal condition. Furthermore, we have provided clinical evidence that the transfer of a single-euploid blastocyst can optimize a patient's pregnancy success while reducing potentially undesirable conditions associated with monochorionic twin pregnancies.
authors.affiliation: Southern California Institute for Reproductive Sciences, Newport Beach, California. Electronic address: scirslab@verizon.net.
authors.forename: Mitchel C
authors.initials: MC
authors.lastname: Schiewe
authors.affiliation: Southern California Institute for Reproductive Sciences, Newport Beach, California.
authors.forename: John B
authors.initials: JB
authors.lastname: Whitney
authors.affiliation: Southern California Institute for Reproductive Sciences, Newport Beach, California; Southern California Center for Reproductive Medicine, Newport Beach, California.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Anderson
mesh_terms: D000328:Adult; D046149:Embryo Culture Techniques / Q000379:methods / Q000639:trends*; D004624:Embryo Transfer / Q000379:methods / Q000639:trends*; D005260:Female; D006801:Humans; D054023:Lasers, Semiconductor / Q000009:adverse effects*; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods / Q000639:trends*; D013997:Time Factors; D014429:Twins, Dizygotic
keywords: Blastocysts; in vitro derived; monochorionic dizygotic twins