Embryo transfer--can we learn anything new from the observation of junctional zone contractions?

To assess whether embryo transfer can alter junctional zone contractility, we studied the effect of easy and difficult mock transfers in 14 oocyte donors during in-vitro fertilization (IVF) cycles. An Echovist bolus (30 microl) was used to represent embryos and transfer medium. An 'easy' transfer was judged to be an atraumatic insertion of the catheter without touching the uterine fundus. A 'difficult' embryo transfer was mimicked by deliberately touching the uterine fundus twice with the soft end of the cannula. Transvaginal scan images were recorded, digitized and converted into five times normal speed to allow us to evaluate junctional zone contractility. Easy mock embryo transfers did not change endometrial mechanical activity. Echovist remained in the upper part of the uterine cavity and was not dispersed after 45 min. A difficult procedure generated strong random waves in the fundal area and waves from fundus to cervix which relocated the Echovist in six out of seven cases. We observed movements of the transfer bolus from the upper part of the uterus towards the cervix (four cases) and into Fallopian tubes (two patients). Our study confirms that the mechanical activity of the uterus is capable of relocating intrauterine embryos and that this activity depends on physical stimulation. Junctional zone contractions can be implicated in cases of IVF/embryo transfer failure or ectopic gestation.