Embryo transfer is a step in the process of assisted reproduction, specifically in vitro fertilization (IVF), in which embryos are placed into the uterus of a female with the intent to establish a pregnancy. The procedure takes place 2 to 5 days after oocyte retrieval, which is the process in which eggs are removed from the ovaries to be fertilized outside of the woman’s body. The embryo transfer procedure starts by placing a speculum in the vagina to visualize the cervix, which is cleansed with saline solution or culture media. A transfer catheter is loaded with the embryos and handed to the clinician after confirmation of the patients identity. The catheter is inserted through the cervical canal and advanced into the uterine cavity. The embryos are then released into the uterus. The procedure takes about 15 minutes and anesthesia or sedation is rarely required. Factors that can affect the success of embryo transfer include the endometrial receptivity, embryo quality, and embryo transfer technique. Embryo transfer can be done at day two or day three, or later in the blastocyst stage, which was first performed in 1984. It is not necessary that the embryo transfer be performed on the female who provided the eggs. Thus another female whose uterus is appropriately prepared can receive the embryo and become pregnant. Embryo transfer may be used where a woman who has eggs but no uterus and wants to have a biological baby; she would require the help of a gestational carrier or surrogate to carry the pregnancy.