title: [Nuclear status of day 2 preembryos affects embryo quality and implantation potential].
abstract: OBJECTIVE
  To assess the effects of the nuclear status of day 2 preembryos on day 3 embryo quality and implantation potential and to weigh its clinical value in the human in-vitro fertilization-embryo transfer (IVF-ET) program.
  
  
  METHODS
  Embryos obtained from 409 fresh conventional IVF-ET/ICSI cycles from July to October 2006 were assessed retrospectively. Day 2 preembryos were classified according to the number of nuclei in each blastomere in 3 groups: grade A with only mononucleated blastomeres, grade B with one or more blastomeres containing no visible nucleus, and grade C with one or more multinucleated blastomeres. Comparisons were made of the rates of arrested embryos and excellent embryos on day 3 as well as of the pregnancy outcome and implantation potential of those in whom cohorts of similar nuclear scoring embryos were transferred.
  
  
  RESULTS
  There were fewer arrested embryos and more excellent embryos on day 3 in grade A than in grade B and C (P < 0.01), and so were there in grade B than in grade C (P < 0.01). Among the 234 cycles in which all the transfer embryos were derived from a similar day 2 nuclear scoring, 51 cycles originated from grade A embryos (group A) and 183 from grade B (group B), with similar clinical pregnancy rates between the two groups, while the implantation rate was higher in group A than in B (P < 0.05).
  
  
  CONCLUSIONS
  Day 2 nuclear scoring can be used to predict the devel- opment and implantation potential of embryos. A combined evaluation of day 2 nuclear scoring and day 3 embryo morphology helps identify the most viable embryos and reduce the number of embryos for transfer.
authors.affiliation: Department of Obstetrics and Gynecology, Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. liuqun626@126.com
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
authors.forename: Gui-Jin
authors.initials: GJ
authors.lastname: Zhu
authors.forename: Juan
authors.initials: J
authors.lastname: Hu
authors.forename: Yu-Lan
authors.initials: YL
authors.lastname: Wei
authors.forename: Xin-Ling
authors.initials: XL
authors.lastname: Ren
authors.forename: Han-Wang
authors.initials: HW
authors.lastname: Zhang
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Jin
authors.forename: Jing
authors.initials: J
authors.lastname: Yue
mesh_terms: D000328:Adult; D001757:Blastomeres; D002467:Cell Nucleus / Q000502:physiology*; D002970:Cleavage Stage, Ovum; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer / Q000706:statistics & numerical data; D005260:Female; D005307:Fertilization in Vitro / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D020554:Sperm Injections, Intracytoplasmic