title: Monozygotic bichorionic twinning after transfer of a single frozen/thawed embryo that has undergone quarter laser-assisted zona thinning: a case report.
abstract: OBJECTIVE
  To present the occurrence of a monozygotic bichorionic twinning after the transfer of a single frozen/thawed embryo has undergone assisted zona hatching (AZH), using a non contact laser.
  
  
  METHODS
  A 33-year-old woman who underwent single frozen embryo replacement (FER). Before transfer, the patient was treated with GnRH agonist and with substitutive therapy (estrogens and progesterone).
  
  
  CONCLUSIONS
  We are absolutely certain that we are reporting a monozygotic bichorionic pregnancy: a single frozen/thawed embryo was transferred and no concomitant spontaneous conception was possible. Moreover, molecular biology assessment for polymorphisms confirmed clinical findings. The possibility of the occurrence of a monozygotic bichorionic twinning after the transfer of a single frozen/thawed embryo should be borne in mind and its incidence will have to be studied further.
authors.affiliation: ANDROS Day Surgery, Reproductive Medicine Unit, Via Ausonia 43/45, Palermo, I-90144, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Allegra
authors.forename: F
authors.initials: F
authors.lastname: Sammartano
authors.forename: P
authors.initials: P
authors.lastname: Scaglione
authors.forename: F
authors.initials: F
authors.lastname: Coffaro
authors.forename: A
authors.initials: A
authors.lastname: Marino
authors.forename: A
authors.initials: A
authors.lastname: Volpes
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007834:Lasers; D018895:Microsatellite Repeats; D011110:Polymorphism, Genetic; D011247:Pregnancy; D038522:Twinning, Monozygotic / Q000235:genetics / Q000502:physiology*; D015044:Zona Pellucida / Q000502:physiology*