title: Frozen embryo transfer: the present practice and beyond.
abstract: BACKGROUND
  With the success of oocyte donation in vitro fertilization (IVF) in postmenopausal women, the importance of endometrial preparation became obvious. This appears also very crucial for achieving pregnancy after frozen embryo transfer (FET) after failed fresh IVF cycles and FET in subsequent natural cycles. Although there are different methods of preparing endometrium, in this study, another method of preparing the implantation bed using letrozole was scrutinized for its usefulness.
  
  
  METHODS
  Two hundred and seventy patients between 28 and 40 years of age undergoing IVF due to bilateral tubal blocks were chosen for FET. They had a previous unsuccessful single IVF attempt or had postponed embryo transfer due to the threat of ovarian hyperstimulation syndrome or poor endometrial development. Informed consents were obtained from the participants. One hundred patients had endometrial preparation by gonadotrophin-releasing hormone agonist down-regulation and with hormone replacement therapy, 55 had natural cycle FET, and the remaining 115 patients had letrozole-induced ovulation induction (OI) for endometrial preparation.
  
  
  RESULTS
  The clinical and biochemical pregnancy rate or live birth rate was higher in the letrozole OI group than in the other two groups.
  
  
  CONCLUSIONS
  OI by letrozole and subsequent endometrial preparation as a result of it may be utilized for FET, and this will be cheap and easy to administer, giving better success rates in FET cycles.
authors: Calcutta Fertility Mission, Kolkata, India.
authors: Anjana Ray
authors: AR
authors: Chaudhuri
authors: Siddhartha
authors: S
authors: Chatterjee
mesh_terms: D000328:Adult; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D004717:Endometrium / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D005615:Freezing; D020249:Hormone Replacement Therapy; D006728:Hormones / Q000502:physiology; D006801:Humans; D000077289:Letrozole; D008597:Menstrual Cycle / Q000502:physiology; D009570:Nitriles / Q000494:pharmacology; D016471:Ovarian Hyperstimulation Syndrome; D010060:Ovulation / Q000187:drug effects; D010062:Ovulation Induction; D011247:Pregnancy; D018873:Pregnancy Rate; D014230:Triazoles / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D006728:Hormones; D009570:Nitriles; D014230:Triazoles; D000077289:Letrozole