Objective: To examine the effect on the pregnancy rate (PR) caused by
air bubbles loaded into the transfer catheter to bracket the embryo-co
ntaining medium.Design: Prospective, randomized study. Setting: One hu
ndred ninety-six consecutive ETs in the Institute of Sterility Treatme
nt. Interventions: Air bubbles were loaded into the transfer catheter
concomitantly with the medium in group I (n = 98), whereas in group II
(n = 98) no air bubbles were used. Results: The PR of group I equals
that of group II. Conclusions: Bracketing the embryo-containing medium
by air bubbles offers several advantages, especially the possibility
of tracking the air on the ultrasound monitor to localize the embryos
after the ET. For these reasons we recommend using the proven method.