A Wallace malleable stylet for difficult embryo transfer in an in vitro fertilization program: a case-control study.

Background: The aim of the study was to evaluate the impact of using a Wallace malleable stylet in combination with an Edwards-Wallace embryo replacement catheter in case of difficult embryo transfer (ET).

Methods: A retrospective case-control study was used. The standard ET procedure at the clinic was to use a single tooth tenaculum, and a speculum to straighten the cervical canal prior to inserting the Edwards-Wallace embryo replacement catheter. In 205 of 2041 (10%) fresh ET difficulties were experienced during ET and a Wallace malleable stylet was used to place the outer catheter sheath correctly. This stylet transfer group was compared with a control transfer group of 410 ET performed just before and after each stylet transfer.

Results: No differences in number of transferred embryos, cleavage stage, or embryo morphology score were found between the two groups. We found no differences in implantation rates (20.7 and 19.2% [95% confidence interval (CI) 0.8-1.5]) or delivery rates (29.3 and 25.4% [CI 0.8-1.8]) between the study and control group.

Conclusion: Using a Wallace malleable stylet in combination with an Edwards-Wallace embryo replacement catheter in case of difficult ET has no negative impact on implantation and delivery rates.