Single Embryo Transfer: Variations in Procedure Techniques

A few years ago, single embryo transfer was thought to be ineffective. Today, single embryo transfer means a woman does not have to risk the chance of a multiple pregnancy. Currently, two variations of single embryo transfer exist. Statistics indicate that in most cases, pregnancy rates do not vary much between single and multiple embryo transfers. Most clinics will offer two variations of single embryo transfer. 

3- Day Embryo Transfer

After a woman’s eggs have been collected, they are placed in a culture that contains the male sperm. The embryo stage occurs two to three days after fertilization. Most practitioners recommend transfer at three days. Although a 2-day transfer is possible, there is a decreased rate of success with the implantation of a single embryo at this stage. 

The day of the embryo transfer, your specialist will arrange to meet you a few hours before the procedure. He will determine which embryo is best suited for implantation and discuss options available for the preservation or donation of remaining embryos. 

During the procedure, your specialist will place the embryo in a fluid filled catheter. Using ultrasound to determine the proper placement, your physician will insert the embryo into your uterus via another special catheter. Approximately two weeks after the transfer, you will return to the clinic for a blood test to determine if you are pregnant. 

Blastocyst (5-Day) Transfer 

An embryo generally reaches the blastocyst stage five days after fertilization. Blastocysts are embryos in which cell differentiation begins with the development of distinct inner and outer cells. The inner cells will eventually develop into the fetus, while the outer cells will form the placenta. By day six, a blastocyst sheds its outer shell and begins to implant itself within the uterine lining. 

After a woman’s eggs have been harvested and placed in the culture medium with the male sperm, the developing embryos are allowed to mature to the blastocyst stage. The blastocyst is then transferred to the uterus, where it will begin to attach itself to the lining. 

Higher success rates have been recorded with blastocyst transfer. The success rate is connected to the development of the embryo. During the course of an unassisted pregnancy, the 2 or 3-day embryo remains in the fallopian tube, until it reaches the blastocyst stage. Next, it travels to the uterus to implant itself in the uterine lining. 

In assisted reproductive technology, the embryo is implanted into the uterus, where it remains while it develops into a blastocyst. The chance of embryonic survival is decreased, because the embryo is forced to develop in a different environment. 

Additionally, not all embryos develop into blastocysts. There is no way of knowing if an embryo will develop to this stage after transfer. By allowing the embryo to develop to this stage in the laboratory, your specialist has the ability to choose the best-developed blastocyst for transfer. 

The method of blastocyst transfer is the same as in embryo transfer. Your physician will arrange to meet you prior to the procedure to discuss their selection. During transfer, the blastocyst will be inserted into your uterus with the aid of a catheter and ultrasound.