Embryo Transfer with Controlled Injection Speed to Increase Pregnancy Rates: A Randomized Controlled Trial.

Background/Aims: Catheter injection speed affects depth and placement of the embryo into the uterine cavity and is shown to be highly variable in, and between, subjects in a manually performed embryo transfer. In an effort to standardize the injection speed during embryo transfer, we developed an automated transfer pump: the pump-regulated embryo transfer (PRET) device. In this randomized controlled trial, we aimed to investigate if standardization of the injection speed and pressure with this PRET results in a better controlled positioning of the transferred embryo(s). Methods: Five hundred ninety-nine in-vitro fertilization/intracytoplasmic sperm injection/frozen-thawed embryo transfer cycles were randomly assigned to the PRET or manual transfer. Positioning of the embryo(s) into the uterine cavity was measured with ultrasound. Results: The PRET device generates a significantly smaller variance of the positioning of the embryo(s) into the uterine cavity. This resulted in an ongoing pregnancy rate of 21% in the PRET versus 17% in the manual (p = 0.22) transfer group; frozen-thawed embryo transfers resulted in 17.5 versus 10.9% (p = 0.097), respectively. Conclusion: The PRET results in better controlled positioning of the embryo(s), and it also gives the opportunity to standardize embryo transfer. Whether the PRET may positively influence pregnancy rates, needs to be investigated in a multicenter trial. (C) 2016 The Author(s) Published by S. Karger AG, Basel