title: What is a difficult transfer? Analysis of 7,714 embryo transfers: the impact of maneuvers during embryo transfers on pregnancy rate and a proposal of objective assessment.
abstract: OBJECTIVE
  To establish the relationship between the degree of difficulty of ET and pregnancy rate (PR), with a view to proposing an algorithm for the objective assessment of ET.
  
  
  METHODS
  Retrospective, observational study.
  
  
  METHODS
  In vitro fertilization unit.
  
  
  METHODS
  Women undergoing assisted reproductive technology (ART) with ET after IVF/intracytoplasmic sperm injection, in whom fresh embryo transfer or frozen-thawed embryo transfer was performed.
  
  
  METHODS
  None.
  
  
  METHODS
  Clinical pregnancy rate (CPR).
  
  
  RESULTS
  A total of 7,714 ETs were analyzed. The CPR was significantly higher in the cases of easy ET compared with difficult ET (38.2% vs. 27.1%). Each instrumentation needed to successfully deposit the embryos in the fundus involves a progressive reduction in the CPR: use of outer catheter sheath (odds ratio [OR] 0.89; 95% confidence interval [CI] 0.79-1.01), use of Wallace stylet (OR 0.71; 95% CI 0.62-0.81), use of tenaculum (OR 0.54; 95% CI 0.36-0.79). Poor ultrasound visualization significantly diminish the CPR.
  
  
  CONCLUSIONS
  The CPR decreases progressively with the use of additional maneuvers during ET. An objective classification of the instrumentation applied during ET is proposed.
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain. Electronic address: alexkava@gmail.com.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Kava-Braverman
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain.
authors.forename: Francisca
authors.initials: F
authors.lastname: Martínez
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Rodríguez
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Álvarez
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain.
authors.forename: Pedro N
authors.initials: PN
authors.lastname: Barri
authors.affiliation: Servicio de Medicina de la Reproducción, Department of Obstetrics, Gynecology and Reproduction, Hospital Universitario Dexeus, Barcelona, Spain.
authors.forename: Buenaventura
authors.initials: B
authors.lastname: Coroleu
mesh_terms: D000465:Algorithms; D016009:Chi-Square Distribution; D015925:Cryopreservation; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005298:Fertility; D005307:Fertilization in Vitro / Q000009:adverse effects; D006801:Humans; D007246:Infertility / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D050498:Live Birth; D016015:Logistic Models; D016017:Odds Ratio; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D056826:Single Embryo Transfer / Q000009:adverse effects / Q000379:methods*; D020554:Sperm Injections, Intracytoplasmic; D016896:Treatment Outcome
keywords: Assisted reproductive techniques; IVF; clinical pregnancy rate; difficult embryo transfer; embryo transfer technique