Standardization of catheter load speed during embryo transfer: comparison of manual and pump-regulated embryo transfer.

The position of transfer air bubbles after embryo transfer is related to the pregnancy rate. With the conventional manual embryo-transfer technique it is not possible to predict the final position of the air bubbles. This position mainly depends on the catheter load speed at transfer (injection speed), a parameter that remains uncontrollable with the conventional technique even after standardization of the protocol. Therefore, the development of an automated device that generates a standardized injection speed is desirable. This study aimed to examine the variation in injection speeds in manual embryo transfer and pump-regulated embryo transfer (PRET). Seven laboratory technicians were asked to perform simulated transfers using the conventional embryo-transfer technique. Their injection speeds were compared with that of a PRET device. The results indicate that in manually performed transfers, even after standardization of the protocol, there is still a large variation in injection speed, while a PRET device generates a reliable and reproducible injection speed and therefore brings new possibilities for further standardization of the embryo-transfer procedure. Future research should reveal whether these experiments mimic real clinical circumstances and if a standardized injection speed results in more exact positioning of the transferred embryos and therefore higher pregnancy rates.