IVF-ET (In Vitro Fertilization and Embryo Transfer)

In Vitro Fertilization Program

Fertilization in vitro involves creating conditions in the lab as close as possible to those in the female reproductive tract.  Embryologists in the laboratory carefully control factors such as nutrients, acidity, humidity, temperature, gas composition of air, and exposure to light.  For the IVF-ET procedure, all of the eggs are retained in the incubator for approximately five hours prior to insemination. The five hour interval between egg retrieval and insemination mimics the time required for the sperm and eggs to travel and meet in the fallopian tube following intercourse and ovulation.  After the insemination, the eggs are left undisturbed in the incubator for 12 to 18 hours.  During this time, approximately 65% of the eggs will fertilize.

The eggs are checked for signs of fertilization at 12 to 18 hours following insemination.  A normal fertilized egg will contain two large structures inside the egg called pronuclei (each individual structure termed a pronucleus).  One pronucleus represents the genetic material from the male partner's sperm. .  The other pronucleus represents the genetic material from the oocyte.  If the egg has been fertilized by more than one sperm, an abnormal condition called "polyploidy" will result.  Polyploid eggs will have three or more pronuclei in their cytoplasm. These eggs are not retained for transfer to the female partner's reproductive tract since they cannot produce a viable baby.  Normal pronuclear-stage embryos in excess of those desired for culture may be cryopreserved for transfer in a later cycle.

Embryo Development Prior to Transcervical Embryo Transfer (IVF-ET)

Embryo Culture and Transfer

The ultimate goal of in vitro fertilization and embryo culture is to transfer high quality embryos that are capable of continued normal development and result in live births.  Achievement of this goal requires the following:

• Optimal in vitro culture conditions
• Reliable embryo selection criteria
• Minimize the risk of multi-fetal pregnancy

Optimizing In Vitro Culture Conditions

In the past decade a more detailed understanding of the embryo’s nutrient and environmental requirements has led to the formulation of culture media capable of supporting development of viable blastocysts (day 5).  Earlier culture media supported embryo development up to the two to eight-cell stage (day two to three), but did not provide the complexity of nutrients required by later stage embryos. 

Embryo Selection Criteria

Embryo selection criteria are currently based on the rate of embryo development and embryo morphology (appearance).  Selection of embryos based on rate of development is similar to selection of the top finishers of a race with novice participants.  Selecting embryos at the one-cell or pronuclear stage is like picking the top finishers of the race before the starting gun.  As the race progresses, a select number of participants take the lead and spectators have a better indication as to which participants will finish the race first.  As with a race, a greater number of competitors (i.e. embryos) usually promote a better finishing time.   We have found that we are able to optimize outcomes by limiting the stress the embryos incur in culture when less than seven embryos are available and by increasing embryo selection through extended culture when more than 6 embryos are available.  We transfer the best embryo(s) on day three (6- to 8-cell stage) when fewer than seven pronuclear-stage embryos are available.  We recommend extended culture to patients with seven or more pronuclear-stage embryos.  For these cases we typically culture seven to eight pronuclear-stage embryos for five days in order to select one to two blastocysts for transfer.  While the extended culture period does stress the embryos more than the short-term culture, we have found that the “extended” race further facilitates selection and transfer of the most viable embryos. 

Minimize the risk of multi-fetal pregnancy

Our program continues to strive to reduce the risk of multi-fetal pregnancy while maintaining pregnancy rates/cycle.  Our goal is one healthy baby at at time.  In order to accomplish this goal our program has set forth the following embryo culture and transfer strategy:

*Only one embryo will be transferred if inclusion criteria met for blastocyst (day five) single embryo transfer

Inclusion criteria for single blastocyst embryo transfer (only one embryo will be replaced):

• Women or oocyte donor must be 37 years of age or younger at the time of the oocyte retrieval.
• Couples must have at least one embryo rated as “good” or “excellent” on day five of culture to proceed with single embryo transfer.  If at least one “good” embryo is not present, then one or two embryos may be transferred.
• No previous history of a failed fresh IVF cycle (oocyte retrieval and embryo transfer) at the University of Iowa.

Inclusion criteria for double blastocyst embryo transfer(couples eligible for transfer of two blastocysts if desired):

• Women 38 years of age or older (or using an oocyte donor 38 years or older) may transfer either one or two embryos based on their desires. 
• Couples who have previously had an unsuccessful fresh IVF cycle (oocyte retrieval and embryo transfer) at the University of Iowa will have the option of transferring either one or two embryos regardless of the grading of the embryos.
• Couples of any age with no embryos rated as “good” or “excellent” on culture day five will have the option of transferring one or two embryos.  We would recommend two embryos be transferred to optimize pregnancy rates.

Transcervical Embryo Transfer

The Procedure

Steps in the transcervical transfer procedure are as follows:

1. The woman is positioned on her back with knees bent and resting on leg supports.
2. A speculum is placed in the vagina to allow the cervix to be seen and cleansed.
3. Embryos and a small amount of nutrient solution are drawn up into a transfer catheter.
4. The transfer catheter is threaded through the cervical canal into the uterus where the embryos are deposited.  Sometimes this may be performed under ultrasound guidance.
5. The woman will be kept flat in bed for 30 minutes in the recovery room and asked to continue to rest for the remainder of the day.

After Transfer

In most cases, you may leave Iowa City after your procedure.  You can expect the following after transfer:

1. Activity—Bedrest in a reclining position of comfort is recommended for the remainder of the day.  Thereafter, strenuous activity and sexual intercourse should be avoided for two weeks after transfer.
2. Daily progesterone injections are prescribed beginning the day of retrieval and continuing daily until the results of the pregnancy test are known.
3. Pregnancy Test – Approximately 15 days after the egg retrieval a pregnancy test will be ordered.  This may be scheduled at UI Hospitals and Clinics or at your local lab.