title: Optimal polar bodies angle for higher subsequent embryo viability: a pilot study.
abstract: OBJECTIVE
  To determine the optimal polar bodies (PB) angle for higher subsequent embryo implantation potential.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Academic fertility center.
  
  
  METHODS
  From January to July 2015, 116 patients were recruited in their first IVF-ET cycles.
  
  
  METHODS
  At the pronuclear stage, PB angle was measured with the use of E-ruler 1.1.
  
  
  METHODS
  The primary outcome measure was good-quality embryo rate. Secondary measures were clinical pregnancy rate (CPR) and embryo implantation rate (IR).
  
  
  RESULTS
  A total of 1,103 oocytes were retrieved. PB angle was measured in 454 zygotes, and 164 of their subsequent embryos were transferred into the uterus. All-or-none implantation took place in 129 embryos, and 89 patients accepted fresh embryo(s) transfer with known PB angle. By means of receiver operating characteristic analysis, the optimal PB angle for subsequent embryo implantation was 24.25°. Based on this cutoff value, 454 zygotes were divided into two groups: small-angle and large-angle. A higher percentage of small-angle zygotes developed into good-quality embryos (70.97% vs. 58.58%). CPR and IR both decreased progressively from purely small-angle embryos to mixed embryos to purely large-angle embryos (CPR: 72.41% vs. 38.46% vs. 26.47%, respectively; IR: 63.27% vs. 26.92% vs. 16.67%, respectively).
  
  
  CONCLUSIONS
  Noninvasive assessment of PB angle is a viable technique for zygote selection and should be included in embryo selection parameters.
  
  
  BACKGROUND
  
  
  
  BACKGROUND
  ChiCTR-OOC-15005882.
authors.affiliation: Center for Reproductive Medicine, Xiang-Ya Hospital, Central South University, Hunan, People's Republic of China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Xiaoyue M
authors.initials: XM
authors.lastname: Guo
authors.affiliation: Center for Reproductive Medicine, Xiang-Ya Hospital, Central South University, Hunan, People's Republic of China. Electronic address: lyp7798@126.com.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Li
mesh_terms: D019540:Area Under Curve; D002470:Cell Survival; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005298:Fertility; D006801:Humans; D007246:Infertility / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D010865:Pilot Projects; D059705:Polar Bodies / Q000473:pathology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D012372:ROC Curve; D027724:Reproductive Techniques, Assisted; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D015053:Zygote / Q000473:pathology*
keywords: Polar bodies; embryo morphology; embryo polarity; implantation