title: Dizygotic twin delivery following in vitro fertilization and transfer of thawed blastocysts cryopreserved at day 6 and 7.
abstract: OBJECTIVE
  To report the first conception and delivery following transfer of thawed human blastocysts maintained in extended in vitro culture with cryopreservation at day 6 and 7.
  
  
  METHODS
  Case report.
  
  
  METHODS
  Major urban infertility referral center.
  
  
  METHODS
  A 26-year-old woman with pelvic endometriosis and two prior unsuccessful in vitro fertilization/embryo transfer (IVF-ET) attempts.
  
  
  METHODS
  The patient underwent controlled ovarian hyperstimulation using a combined FSH + hMG protocol, and 24 oocytes were retrieved.
  
  
  METHODS
  Dizygotic twin delivery after IVF and intracytoplasmic sperm injection (ICSI), assisted embryo hatching, and ultrasound-guided transfer of cryopreserved blastocysts.
  
  
  RESULTS
  After three embryos were subjected to assisted hatching, they were transferred fresh on day 3, but no implantation occurred. All nontransferred embryos (n = 11) were observed during extended in vitro culture and three blastocysts were selected for cryopreservation on day 6 and 7; thaw and transfer occurred the following month and a pregnancy was achieved. Dizygotic twins (female/female) were delivered by cesarean in the early third trimester.
  
  
  CONCLUSIONS
  Substantial advancements have been made in the field of embryo cryogenics and in vitro fertilization, but controversy remains regarding the value of freezing late-developing human blastocysts. Here we describe the first reported live births with IVF after extended in vitro culture and cryopreservation at day 6 and 7 after fertilization.
authors.affiliation: Georgia Reproductive Specialists LLC, Atlanta, USA. dr.sills@ivf.com
authors.forename: E Scott
authors.initials: ES
authors.lastname: Sills
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Sweitzer
authors.forename: Paula C
authors.initials: PC
authors.lastname: Morton
authors.forename: Mark
authors.initials: M
authors.lastname: Perloe
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Kaplan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tucker
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology*; D015925:Cryopreservation / Q000379:methods*; D036861:Delivery, Obstetric; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic; D014429:Twins, Dizygotic