The pre-cycle blind mock embryo transfer is an inaccurate predictor of anticipated embryo transfer depth.

Purpose: To assess if the uterine cavity depth measured by a blind pre-cycle mock transfer changes after gonadotropin stimulation.

Methods: This is a retrospective cohort study at an academic IVF program involving 128 infertility patients. The main outcome measures were uterine cavity depth measured at the blind pre-stimulation mock transfer and the ultrasound-guided embryo transfer.

Results: A >or= 1 cm increase in uterine cavity depth was found in 57.9% of the patients. The mean pre-cycle blind mock transfer uterine depth significantly differed from the mean uterine depth measured at embryo transfer. Based on the mock transfer, the anticipated embryo transfer depth was significantly less than the actual ultrasound-guided embryo transfer depth.

Conclusion: Uterine depth significantly differed between the blind pre-cycle mock transfer measurement and the ultrasound-guided embryo transfer measurement. The mock transfer may predict a difficult embryo transfer but it is an inaccurate predictor of the final embryo transfer depth.