The embryos can be transferred between the 2nd and 6th days following egg collection. The number of embryos to transfer and the date of transfer are decided after evaluating the number and quality of embryos, age of the woman, whether she has attempted for a test tube baby, and many other factors.
Transfer process is very similar to an examination and usually painless but some patients may experience cramp-like mild pains. Prior to transfer, future mother’s bladder needs to be half full because transfer process is guided by ultrasound. Clinician uses a vaginal speculum to fix the cervix. One or more embryos collected into the culture medium are drawn into the transfer catheter which is a long thin sterile tube attached to an injector.
Clinician passes the end of transfer catheter through the cervix and places the fluid containing embryos into the uterine space.
This procedure does not require anesthesia but some patients request a mild sedation. If the development of embryos achieved in vitro continues inside the uterus, ‘zona pellusida’ surrounding the embryo decomposes (hatching) and then the embryo attaches to the wall of the uterus 6-10 after egg collection (implantation).