Embryo transfer typically occurs 3 to 5 days after egg retrieval. The procedure usually takes just 10 to 15 minutes, with an additional 30-minute rest period. Sedation is not required but the patient is required to have a mildly full bladder so the physician can visualize the uterus using an abdominal sonogram.
The physician prepares the patient by inserting a speculum to widen the cervix, and swabbing it with a non-toxic solution. The embryologist loads the selected embryo(s) into a specially designed embryo transfer catheter, a very soft, flexible plastic tube. When the patient is appropriately prepared, the embryologist delivers the catheter containing the embryos to the procedure room.
During the procedure, the physician gently threads the catheter through the cervix and into the uterine cavity. Once complete, the embryologist examines the catheter to confirm that all embryos were deposited into the uterus. Patients are required to rest for approximately 30 minutes before being discharged. A small amount of watery discharge is likely post-transfer; this is the fluid that was used to clean the cervix, and is not the culture medium that was transferred with the embryos.
The transfer of more than one embryo increases the likelihood of establishing a pregnancy. However, the risk of multiple pregnancy increases as more embryos are replaced. Factors affecting the likelihood of pregnancy (and multiple pregnancy) include the patient’s age, embryo quality, the specific cause(s) of infertility and a couple’s reproductive history.
Couples have an opportunity to discuss their personal preferences related to embryo transfer with their physician prior to the start of the IVF cycle. At the time of the embryo transfer, the physician will discuss the quality of the embryos and the probability of pregnancy and multiple pregnancy. When embryo quality is high, and in the absence of other considerations, we typically transfer two embryos to patients under age 36, three embryos to patients 36-39, and four embryos to patients older than 39.
High quality embryos that are not transferred may be cryopreserved. However, the success rates for cryopreservation are greater for younger patients; therefore, IRMS rarely freezes embryos for patients age 40 and older.