title: The effect of air bubble position after blastocyst transfer on pregnancy rates in IVF cycles.
abstract: OBJECTIVE
  To investigate the relationship between air bubble position after blastocyst transfer (BT) and pregnancy rates (PRs).
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  University-based infertility center.
  
  
  METHODS
  Three hundred fifteen consecutive nondonor BTs by a single provider.
  
  
  METHODS
  Catheters were loaded with 25 μL of culture media, 20 μL of air, 25 μL of media containing the blastocysts, 20 μL of air, and a small amount of additional media. The distance from the air bubble to the fundus, as seen on abdominal ultrasound examination, was measured at the time of transfer. Air bubble location was categorized as <10 mm, 10-20 mm, and >20 mm from the fundus.
  
  
  METHODS
  Clinical pregnancy rate.
  
  
  RESULTS
  After controlling for age, parity, FSH and frozen transfers, and accounting for repeated cycles per patient, the PRs for both the >20-mm (38.3%) and the 10-20-mm (42.0%) from the fundus group were significantly reduced compared with the group in which the bubble was <10 mm from the fundus (62.5%).
  
  
  CONCLUSIONS
  This study is the first to suggest that BT closer to the fundus is associated with higher PR. Although no ectopic pregnancies occurred in the <10-mm group, this outcome should be monitored closely in larger studies.
authors.affiliation: Stanford Fertility and Reproductive Medicine Center, Palo Alto, California 94304, USA. Brookef1@Stanford.edu
authors.forename: Brooke E
authors.initials: BE
authors.lastname: Friedman
authors.forename: Ruth B
authors.initials: RB
authors.lastname: Lathi
authors.forename: Melinda B
authors.initials: MB
authors.lastname: Henne
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Fisher
authors.forename: Amin A
authors.initials: AA
authors.lastname: Milki
mesh_terms: D000328:Adult; D000388:Air; D002970:Cleavage Stage, Ovum; D015331:Cohort Studies; D003470:Culture Media; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D045423:Microbubbles; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies
chemical_list: D003470:Culture Media