Embryo transfer: techniques and variables affecting success

Objective: To review the literature on the variables affecting embryo trans fer success or failure and to define technical factors associated with opti mal outcome. Design: Literature review. Results: Avoidance of blood, mucus, bacterial contamination, excessive uter ine contractions, and trauma to the endometrium is associated with optimal pregnancy and implantation rates after transcervical embryo transfer. A tri al transfer, ultrasonographic guidance, and use of "soft" catheters appear to facilitate successful embryo transfer. Conclusion: An understanding of the variables associated with embryo transf er success together with adherence to techniques shown to facilitate atraum atic embryo transfer will enhance the efficiency of IVF by maximizing embry o implantation. (C) 2001 by American Society for Reproductive Medicine.