[Impact of embryo transfer techniques on implantation rates]

Embryo transfer is an important step in the success of IVF treatment. All efforts should be made to avoid difficult embryo transfers provoking bleeding or uterine contractions. Evaluation before IVF treatment, including a trial transfer and a uterine ultrasonography, should allow one to evaluate the transfer step, anticipate problems, and thus improve treatment. An hysteroscopy can be useful for uterine cavity exploration. It is also important to remove cervical mucus before introduce the transfer catheter. It is essential to deposit embryos as gently as possible during IVF, avoiding manoeuvres that might trigger uterine contractions which could adversely affect the results of this treatment. Soft catheters perform better, and ultrasound-guidance facilitates embryo transfer. Progesterone administration starting on the day of oocyte retrieval induces a decrease in uterine contraction frequency on the day of ET (embryo transfer). Both Wallace and CDD catheters perform similarly. Trial catheterization on the day of ET could prevent most of the unanticipated procedural difficulties during the transfer.