Air in the transfer catheter does not affect the success of embryo transfer.
OBJECTIVE: To investigate the effect on embryo transfer (ET) success of air loaded into the transfer catheter to bracket the embryo-containing medium. DESIGN: Prospective, randomized study. SETTING: University teaching hospital. PATIENT(S): One hundred two consecutive patients undergoing ET after IVF. INTERVENTION(S): In group 1 (n = 52), embryos were loaded as follows: 200 microL of air in the syringe, 100-125 microL of air in the proximal part of the catheter, 20-25 microL of medium containing the embryos to be transferred, and 10 microL of air at the tip of the catheter. In group 2 (n = 50), the syringe and the entire catheter were filled with medium and the embryo-containing medium (20-25 microL) was aspirated without being bracketed by air spaces. MAIN OUTCOME MEASURE(S): Implantation and pregnancy rates. RESULT(S): No differences were found between groups 1 and 2 with respect to implantation and pregnancy rates. CONCLUSION(S): The air loaded into the transfer catheter to bracket the embryo-containing medium has no negative effect on ET success.