title: A randomized controlled clinical trial of 2295 ultrasound-guided embryo transfers.
abstract: BACKGROUND
  We wanted to test the hypothesis that using abdominal ultrasound at the time of embryo transfer to guide replacement, improved pregnancy rates by at least 5%.
  
  
  METHODS
  An RCT in a large assisted conception unit. A pilot study and power calculation suggested that at least 2000 embryo transfers were required to demonstrate a difference of 5%, for a test with 80% power and Type 1 error 0.05. Randomization, data entry and analysis were arranged independently. Randomization was stratified for age and fresh/frozen embryo transfer. Analysis was by intention to treat.
  
  
  RESULTS
  There was no difference in clinical pregnancy or live birth rates between the two groups. The clinical pregnancy rate for ultrasound-guided embryo transfer was 22% and for non-ultrasound-guided embryo transfer was 23% (odds ratio: 0.96; 95% confidence interval: 0.79-1.18).
  
  
  CONCLUSIONS
  We set out to determine whether ultrasound-guided embryo transfer improved clinical pregnancy rates and live birth rates in assisted conception. We used an appropriately powered RCT design. We did not demonstrate a difference. This outcome is at odds with the UKs National Institute of Clinical Excellence recommendations for fertility treatment (Fertility Assessment and Treatment for People with Fertility Problems. London, UK: RCOG Press, 2004, 112.) which used a meta-analysis of four smaller trials (range 362-800 patients, totalling 2051 embryo transfers) to conclude that ultrasound should be offered. We suggest that the current Cochrane review should be updated with data from our trial and recommend that consideration is given to accounting for heterogeneity between the included trials.
authors.affiliation: Hewitt Centre for Reproductive Medicine, Liverpool Women's Hospital NHS Foundation Trust, Crown Street, Liverpool L8 7SS, UK. adrakeley@yahoo.com
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Drakeley
authors.forename: Andrea
authors.initials: A
authors.lastname: Jorgensen
authors.forename: John
authors.initials: J
authors.lastname: Sklavounos
authors.forename: Thomas
authors.initials: T
authors.lastname: Aust
authors.forename: Rafet
authors.initials: R
authors.lastname: Gazvani
authors.forename: Paula
authors.initials: P
authors.lastname: Williamson
authors.forename: Charles R
authors.initials: CR
authors.lastname: Kingsland
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging*; D000328:Adult; D004624:Embryo Transfer / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005615:Freezing; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D012680:Sensitivity and Specificity; D014463:Ultrasonography