Embryo placement in IVF and reproductive outcomes: a cohort analysis and review

The objective of the present study was to determine the influence of the embryo placement depth on the endometrial cavity in relation to the reproductive outcomes, after frozen-thawed embryo transfer performed under transabdominal ultrasound guidance.

Retrospective cohort study that evaluated the influence of the embryo placement depth in the endometrial cavity in relation to the reproductive outcomes of patients submitted to cryotransfer cycles at a private assisted reproduction clinic, from 2012 to 2017. The patients were classified according to three variables: <10mm, 10 to 15mm and >15mm. The primary outcome was clinical pregnancy, and the secondary outcomes were miscarriage, ongoing pregnancy and live birth. The data was summarized as relative risk, with a 95%CI.

Clinical and ongoing pregnancy rates were higher in the 10-15mm and >15mm Groups, when compared to the <10mm Group; there was no statistical difference between the groups in terms of miscarriage and live birth rates. We performed a subsequent analysis, using the same sample of patients, comparing only the <10mm and ≥10mm variables. The ≥10mm Group had better reproductive outcomes, with higher clinical and ongoing pregnancy rates.

Pregnancy rates are influenced by embryo transfer site, and better results can be achieved when the tip of the catheter is placed in the central area of the endometrial cavity, especially when the distance from the endometrial fundus is >10mm.