Implantation -it's close to a "Lunar Landing"
You have gotten so far as embryo transfer and been told you have an"excellent blastocyst" embryo, or take it a step further. You have done preimplantation genetic testing on your embryos and know you are transferring a reportedly "genetically normal"embryo. Well, that's a slam dunk-right? Not so fast!! The embryo has many difficult obstacles to overcome!
Implantation-placentation, two very important events for the success of a pregnancy. Not only for the initial stages of early pregnancy but for the entire pregnancy to have a successful outcome.
The embryo makes it to the endometrial lining approximately 5-7 days after fertilization if the pregnancy occurs naturally and day 5 if placed in uterus with IVF/embryo transfer. It's not simple placement at this point.
The embryo faces much stress during this time to find its apposition.
Apposition is a "shaky touchdown" that relies on cytokines & chemokines to mediate the communication between the embryo and endometrium to guide it to it's "docking station". It is imperative that the "window of implantation" is accurate. Many factors are involved at this time making the communication between the embryo and endometrium successful. The 2nd step is attachment or adhesion of the blastocyst to the endometrium. The final step is invasion in which penetration occurs to such a degree that it places the placental trophoblast directly in contact with the maternal blood supply firming up that final, albeit critical step of establishing blood supply. Think if it simply as seed - "embryo" & soil - "endometrium". Healthy seed in a rich soil environment certainly implies the importance of the "window if implantation".
How can we influence this all important "window"? We believe that proper selection of the most competent embryos-both by morphological grading and /or by preimplantation genetic screening is the first step. Secondly, allowing the proper "staging" of the endometrium, without the influence of the hyper-estrogenic state that occurs during IVF stimulation.
Again, our practice philosophy of frozen transfer over fresh, allows for very careful preparation of the endometrium. During this process, we perform an endometrial "scratch" approximately 4-5 weeks prior to transfer. The endometrial scratch is a simple 5 minute procedure in which a thin catheter is placed in the uterine cavity and gently "scratches" the 4 quadrants of the endometrial cavity, triggering production of the all important growth factors, cytokines, chemokines, and gene expressions which are all so important in "jump starting" this all intricate communication process.