title: Quantitative grading of a human blastocyst: optimal inner cell mass size and shape.
abstract: OBJECTIVE
  To investigate the predictive value of quantitative measurements of blastocyst morphology on subsequent implantation rates after transfer.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Private assisted reproductive technology center.
  
  
  METHODS
  One hundred seventy-four IVF patients receiving transfers of expanded blastocyst-stage embryos on day 5 (n = 112) or day 6 (n = 62) after oocyte retrieval.
  
  
  METHODS
  None.
  
  
  METHODS
  Blastocyst diameter, number of trophectoderm cells, inner cell mass (ICM) size, ICM shape, and implantation and pregnancy rates.
  
  
  RESULTS
  Blastocyst diameter and trophectoderm cell numbers were unrelated to implantation rates. Day 5 expanded blastocysts with ICMs of >4,500 microm(2) implanted at a higher rate than did those with smaller ICMs (55% vs. 31%). Day 5 expanded blastocysts with slightly oval ICMs implanted at a higher rate (58%) compared with those with either rounder ICMs (7%) or more elongated ICMs (33%). Implantation rates were highest (71%) for embryos with both optimal ICM size and shape. Pregnancy rates were higher for day 5 transfers of optimally shaped ICMs compared with day 5 transfers of optimally sized ICMs.
  
  
  CONCLUSIONS
  Quantitative measurements of the inner cell mass are highly indicative of blastocyst implantation potential. Blastocysts with relatively large and/or slightly oval ICMs are more likely to implant than other blastocysts.
authors.affiliation: Fertility Center of Las Vegas, Las Vegas, Nevada 89117, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Richter
authors.forename: D C
authors.initials: DC
authors.lastname: Harris
authors.forename: S T
authors.initials: ST
authors.lastname: Daneshmand
authors.forename: B S
authors.initials: BS
authors.lastname: Shapiro
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology* / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D018709:Statistics, Nonparametric