Increasing Pregnancy by Improving Embryo Transfer Techniques

Embryo transfer (ET) is universally recognized as the final and most critical stage in an in vitro fertilization (IVF) outcome (Neithardt et al., 2005; Ghazzawi et al., 1999). The majority of couples (approximately 80%) who undergo IVF reach the embryo transfer stage, yet few pregnancies occur (Mansour & Aboulghar, 2002; Adamson et al., 2006). Although embryo genetic abnormalities (Munne et al., 1995) and imperfections in uterine receptivity are some important factors which influence implantation, embryo transfer technique may be directly responsible for a lot of unsuccessful embryo implantations. Embryo transfer necessitates the joint attempts of the reproductive biologist and the clinician. Without healthy embryos, embryo transfer will fail. On the other hand, a poor embryo transfer technique often results in embryo implantation failure (Schoolcraft et al., 2001). However, comparatively less attention has been paid to ET techniques than IVF technique (Mansour & Aboulghar, 2002; Schoolcraft et al., 2001). This might be due to misconception of some clinicians in which the type of transfer does not affect the outcome (Schoolcraft et al., 2001). The early researchers recommended that a careful embryo transfer technique is necessary for successful IVF (Meldrum et al., 1987). Recently, many investigators have identified the relationship between IVF outcome and different techniques and they have noted a pregnancy rate of 33.3% for “excellent” transfers, and 10.5% for “poor” transfers (Englert et al., 1986, as cited in Schoolcraft et al., 2001). In this chapter we attempt to review the variables and, techniques that may refine the embryo transfer technique and divide them to the following three stages: before, during, and after embryo transfer.