title: A randomized controlled trial of a soft double lumen embryo transfer catheter versus a firm single lumen catheter: significant improvements in pregnancy rates.
abstract: BACKGROUND
  Embryo transfer has changed little since originally described in 1978. Clinicians rate the type of catheter used as the third most important variable in embryo transfer, but there are no adequately powered randomized trials. We compared the clinical pregnancy rates with the single lumen catheter (TCC) and the double lumen catheter (CC) in a randomized single blind trial.
  
  
  METHODS
  A total of 650 cycles of women from the Adelaide University reproductive medicine units in Australia were included in this trial. Patients were <40 years of age undertaking IVF and embryo transfer. Exclusion criteria were: known uterine abnormality, day 3 FSH >10 IU/l, previous difficult embryo transfer and pre-implantation genetic diagnosis. Cycles were randomized from numbered sealed envelopes immediately prior to embryo transfer with stratification for fresh or frozen cycles.
  
  
  RESULTS
  There was a significantly higher pregnancy rate in the group treated with the CC compared with the TCC catheter [29.6 versus 20.5% per embryo transfer, odds ratio (OR) = 1.63 (95% confidence interval: 1.14-2.30), P = 0.0076]. The point estimate for the OR was similar for fresh and frozen cycles.
  
  
  CONCLUSIONS
  The pregnancy rate was increased by 50% and this justifies the increased cost of the soft double lumen catheter and the training of clinical staff required.
authors.affiliation: Suite 14, John James Medical Centre, 175 Strickland Crescent, Deakin, ACT 2600, Australia. buckdonald@netspeed.com.au
authors.forename: Janelle A
authors.initials: JA
authors.lastname: McDonald
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Norman
mesh_terms: D000328:Adult; D002404:Catheterization; D004624:Embryo Transfer / Q000295:instrumentation*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D016017:Odds Ratio; D011247:Pregnancy; D011446:Prospective Studies; D016037:Single-Blind Method