Best site for embryo transfer: the upper or lower half of endometrial cavity?

BACKGROUND: The objective of the present study was to determine the importance of the site of embryo transfer (upper or lower half endometrial cavity) on implantation and clinical pregnancy rates. METHODS: A total of 400 transfers guided by ultrasound were randomly assigned to two groups according to the distance between the uterine fundus and the catheter tip at the time of embryo placement. Group I (n=200) consisted of transfers corresponding to a distance of 0.05) between groups I and II. No significant difference in implantation or pregnancy rates was observed between groups I and II. CONCLUSION: The implantation or pregnancy rates were similar whether the embryos were deposited in the upper or lower half of the endometrial cavity.