title: IVF outcome is optimized when embryos are replaced between 5 and 15 mm from the fundal endometrial surface: a prospective analysis on 1184 IVF cycles.
abstract: BACKGROUND
  Some data suggest that the results of human in vitro fertilization (IVF) may be affected by the site of the uterine cavity where embryos are released. It is not yet clear if there is an optimal range of embryo-fundus distance (EFD) within which embryos should be transferred to optimize IVF outcome.
  
  
  METHODS
  The present study included 1184 patients undergoing a blind, clinical-touch ET of 1-2 fresh embryos loaded in a soft catheter with a low amount of culture medium. We measured the EFD using transvaginal US performed immediately after ET, with the aim to assess (a) if EFD affects pregnancy and implantation rates, and (b) if an optimal EFD range can be identified.
  
  
  RESULTS
  Despite comparable patients' clinical characteristics, embryo morphological quality, and endometrial thickness, an EFD between 5 and 15 mm allowed to obtain significantly higher pregnancy and implantation rates than an EFD above 15 mm. The abortion rate was much higher (although not significantly) when EFD was below 5 mm than when it was between 5 and 15 mm. Combined together, these results produced an overall higher ongoing pregnancy rate in the group of patients whose embryos were released between 5 and 15 mm from the fundal endometrial surface.
  
  
  CONCLUSIONS
  The site at which embryos are released affects IVF outcome and an optimal EFD range exists; this observations suggest that US-guided ET could be advantageous vs. clinical-touch ET, as it allows to be more accurate in releasing embryos within the optimal EFD range.
authors.forename: Valentina
authors.initials: V
authors.lastname: Rovei
authors.forename: Paola
authors.initials: P
authors.lastname: Dalmasso
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gennarelli
authors.forename: Teresa
authors.initials: T
authors.lastname: Lantieri
authors.forename: Gemma
authors.initials: G
authors.lastname: Basso
authors.forename: Chiara
authors.initials: C
authors.lastname: Benedetto
authors.affiliation: Physiopatology of Reproduction and IVF Unit, Department of Surgical Sciences, University of Torino, Sant'Anna Hospital, Torino, Italy. fertisave@yahoo.com.
authors.forename: Alberto
authors.initials: A
authors.lastname: Revelli
mesh_terms: D000328:Adult; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D016896:Treatment Outcome; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging