title: Ultrasound-guided embryo transfer: a prospective randomized controlled trial.
abstract: BACKGROUND
  Recent reports suggested that ultrasound guidance during embryo transfer might improve the pregnancy rate.
  
  
  METHODS
  A prospective randomized controlled trial was performed to compare embryo transfer under ultrasound guidance versus the clinical touch method. A total of 800 embryo transfers was studied; 400 were randomized to ultrasound-guided transfers and 400 were randomized to the clinical touch group. Of these, 441 were fresh cycles and 359 were frozen-thawed cycles.
  
  
  RESULTS
  The clinical pregnancy rate was 26.0% in the ultrasound-guided group and 22.5% in the clinical touch group; the difference was not statistically significant. The ongoing pregnancy rate was 23.5% in the ultrasound-guided group compared with 19.0% in the clinical touch group and the difference was again not statistically significant. The implantation rate was slightly higher in the ultrasound-guided group (15.3%) than the clinical touch group (12.0%) (P = 0.048). There were no differences in the incidences of ectopic pregnancy, miscarriage and multiple pregnancy between the two groups.
  
  
  CONCLUSIONS
  A significant improvement in implantation rate was observed following the use of ultrasound guidance during embryo transfer. The extent of improvement in the pregnancy rate may depend on the specific techniques and methods of embryo transfer used in individual centres.
authors.affiliation: Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China. ostang@graduate.hku.hk
authors.forename: O S
authors.initials: OS
authors.lastname: Tang
authors.forename: E H
authors.initials: EH
authors.lastname: Ng
authors.forename: W W
authors.initials: WW
authors.lastname: So
authors.forename: P C
authors.initials: PC
authors.lastname: Ho
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D011271:Pregnancy, Ectopic / Q000453:epidemiology; D011272:Pregnancy, Multiple; D011446:Prospective Studies; D014463:Ultrasonography