title: The usefulness of ultrasound guidance in frozen-thawed embryo transfer: a prospective randomized clinical trial.
abstract: BACKGROUND
  Recent randomized controlled trials have shown that implantation and pregnancy rates were improved with ultrasound-guided embryo transfer compared with clinical touch in fresh IVF cycles associated with supraphysiological ovarian steroid levels. However, the usefulness of ultrasound guidance in frozen-thawed embryo transfer where potential hormonal influences are lacking has not been appropriately investigated.
  
  
  METHODS
  A total of 184 consecutive patients undergoing thawed embryo transfer cycles with hormone replacement under pituitary suppression were randomized by computer-generated randomization table to two study groups: 93 had ultrasound-guided (group 1) and 91 had clinical touch (group 2) embryo transfer.
  
  
  RESULTS
  There was equal distribution between the two study groups with respect to the main demographic and baseline characteristics of the patients as well as the characteristics of both prior IVF cycles from which embryos were generated and cryopreserved-thawed embryo transfer cycles. However, both pregnancy and implantation rates in group 1 (34.4 and 19.8% respectively) were significantly higher than the corresponding values (19.7 and 11.9%) in group 2.
  
  
  CONCLUSIONS
  Ultrasound guidance in frozen-thawed embryo transfer significantly increases pregnancy and implantation rates.
authors.affiliation: Department of Obstetrics and Gynaecology, Institut Universitari Dexeus, Faculty of Medicine-University of Barcelona, Hospital Clinic-Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. vencor@iudexeus.uab.es
authors.forename: Buenaventura
authors.initials: B
authors.lastname: Coroleu
authors.forename: Pedro N
authors.initials: PN
authors.lastname: Barri
authors.forename: Olga
authors.initials: O
authors.lastname: Carreras
authors.forename: Francisca
authors.initials: F
authors.lastname: Martínez
authors.forename: Anna
authors.initials: A
authors.lastname: Veiga
authors.forename: Juan
authors.initials: J
authors.lastname: Balasch
mesh_terms: D000328:Adult; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D004622:Embryo, Mammalian; D004967:Estrogens / Q000627:therapeutic use; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000627:therapeutic use; D019233:Retreatment; D014463:Ultrasonography
chemical_list: D004967:Estrogens; D011374:Progesterone