How often does the embryo implant at the location to which it was transferred?

• Published in: Ultrasound in obstetrics & gynecology 2016-07, Vol.48 (1), p.106-112
• Main Authors: Saravelos, S. H., Wong, A. W. Y., Chan, C. P. S., Kong, G. W. S., Li, T.‐C.
• Format: Article
• Language: English
• Subjects: Adult; Embryo Implantation; Embryo Transfer; Embryo, Mammalian - diagnostic imaging; Female; Humans; Imaging, Three-Dimensional; Pregnancy; Prospective Studies; three‐dimensional; Ultrasonography, Prenatal; ultrasound
• ISSN: 0960-7692; 1469-0705
• DOI: 10.1002/uog.15778

Objective To determine how often the embryo implants exactly at the site of transfer and what additional factors may affect the eventual site of implantation in assisted reproductive technology (ART) cycles. Methods This was a prospective observational study of women undergoing ART treatment in a tertiary university unit. Several factors inherent to the embryo transfer (ET), such as the location of the air bubbles and uterine contractility at 1 and at 60 min after ET were assessed with two‐dimensional and three‐dimensional (3D) ultrasound. In women in whom there was a resulting pregnancy, the position of the gestational sac (i.e. right, left, center or low) was subsequently assessed using 3D ultrasound, and predictors of its location were evaluated. Results Of 239 recruited women with visualization of air bubbles at ET, 71 singleton gestational sacs were subsequently observed on 3D ultrasound. Overall, 40.8% (29/71) of embryos implanted at the location where the air bubbles were visualized at 1 min after ET, and 50.7% (36/71) implanted where the air bubbles were visualized at 60 min after ET (Cohen's kappa coefficients 0.21 and 0.37, respectively; comparison of agreement values: P = 0.28). Specifically, at 1 min the correspondence between the location of the air bubble and embryo implantation was 37.5% (6/16), 57.1% (8/14), 36.8% (7/19) and 36.4% (8/22) for right, left, central and lower uterus, respectively (4 × 4 contingency table, P