Embryo reduction

Multiple pregnancies occur after an IVF treatment very often. Thus, during natural conception number of multiple pregnancies barely exceeds 1% of the total number, as a result of IVF procedure multiple pregnancies (twins, triplets and quadruplet) occur in every second case!

In vitro fertilization is an unpredictable process, during which doctors always prefer to have some embryos as a reserve. It was fixed that the probability of successful pregnancy is higher if several fertilized eggs is transplanted into the uterus. 20 years ago it was a practice to transfer 8-9 embryos, 2-3 or even 4 of them survived. But in course of time, doctors managed to improve the quality of fertilization, so it was enough to transfer 4-3 embryos. Unfortunately, it was imposable to avoid multiple pregnancies even then. 

It should be noted that today everywhere (both in Ukraine and all over the world) standard embryo transfer during IVF procedure rarely exceed two embryos. In some countries, if the patient’s age is under 30 years, no more than one embryo is transferred. Tendency for effectiveness improvement during in vitro fertilization procedure leads to reduction of embryos’ number used for one cycle of IVF. But nevertheless.

Multiple pregnancies (especially triplets and quadruplet) have a high risk both for mother and future babies. Perinatal mortality, especially when there are more than two fetuses, increases by 60%.  Most often, second and third fetus run the danger of death. Typically, it is caused by the problems of labor management.

A fetal reduction, that is reduction of superfluous embryos, may be suggested by doctors to reduce the risk of complications.

History

For the first time, embryo reduction was made in 1978. At first, this manipulation was made in the case when one of two embryos has any serious pathology. With the introduction of this method, woman pregnant with twins, have a chance to avoid birth of a seriously ill child, while saving life of another child.

Since 1986, reduction of embryo was used to reduce viable embryos in the case of multiple pregnancy. Most often, it occurs after in vitro fertilization procedure. Doctors gave patients with triplets and quadruplet an opportunity to leave one or two children, thereby reducing the risk of complications. But over time it became clear that reduction of IVF has a lot of negative consequences as well.

Embryo reduction can be used if:

  • there are more than three viable embryos;
  • rarely if women asks for this procedure having two embryos.

Conditions needed to carry out embryo reduction:

  • legal patient's agreement;
  • necessary technical and sanitary conditions, which meet all standards for embryo reduction procedure carrying;
  • specialist who have all skills and knowledge to held embryo reduction procedure;
  • gestational age from 7 to 11 weeks. 

Methods of embryo reduction

Embryo reduction is the practice of reducing the number of fetuses by stopping the heart beats of one or more of them using a special drug. Fetal reduction may be seen as a very unusual procedure, as it is carried out after a couple spends a long and hard time trying to get pregnant; however, the objective of IVF treatment is not to maximize the number of fetuses but to help you give birth to a healthy baby that you can take into your arms and bring home.

The procedure is performed under ultrasound guidance between weeks 10 and 12 of pregnancy. A very thin needle is injected through the patient's abdomen. The needle, which contains potassium chloride, is then injected into the heart or surrounding tissue of the targeted fetus(es). Before the procedure, the fetuses are assessed one by one. Doctor carries out the operation on the fetus(es) that displayed problems or the one(s) that he or she can reach easily. The procedure is carried out under ultrasound guidance in order to avoid any damage to the fetuses that will not be operated on.

Reduction of the number of fetuses drastically reduces the risk of preterm deliveries, disorders, fatalities and deformities in babies. Your chances of having a healthy baby increase with a fetal reduction procedure.

Three embryo reduction techniques are used in medical centers of reproductive medicine: transabdominal, transcervical and transvaginal. The transabdominal technique, which is performed between the ninth and 14th weeks of pregnancy, involves injection of NaCl or KCl solution near to or inside the fetal heart, and/or amniotic fluid aspiration. The method entails a greater technical difficulty, with miscarriage rates ranging from 10.6% to 40%, and pre-term labour ranging from 20% to 64% of the cases. The transcervical technique consists of a mechanical cervical dilatation performed between the eighth and ninth weeks, followed by an embryo aspiration through the cervix using a Karman or a number 8metallic cannula. This technique is no longer used on a practical basis due to the high complication rates, including chorioamnionitis, bleeding (33%) and miscarriage (12–24.8%). The transvaginal technique is performed between the seventh and 11th weeks, by injecting NaCl or KCl solution into the fetal thorax. The injection of such substances into the embryo or fetal thorax is not a risk-free procedure however, and cases of anencephaly or limb amputation have been described. If the KCl solution accidentally reaches the amniotic fluid of the remaining embryos, this could result in a total pregnancy loss.

What are the associated risks?

There is a 6 percent risk that a woman may lose the entire pregnancy after a fetal reduction from triplets to twins. This is equal to the risk of miscarriage in twin pregnancies. As the number of fetuses reduced increases, the risk of losing the entire pregnancy increases to 10 percent. However, you should remember that if you are expecting triplets or more, your chances of having a preterm delivery reach about 100 percent. Therefore, reduction is recommended for triplet and other multiple pregnancies.

Conclusion

Debates about what should be the optimal number of embryos to be transplanted into the uterus during the implementation of IVF procedure, do not cease to these days. Anyway, the final decision on the reduction is up to the woman. However, she should be informed of all the possible nuances that occur during a multiple pregnancy, what the consequences might be without the reduction, and as a result of its use.

In addition, patient needs to know, what is the reduction of IVF is made for, using what method will be carried out the operation, what is frequency of complications arising later. Doctors have to inform in details woman and her husband on this issue, only after that patient signs an appropriate agreement on embryo reduction carrying.

Today, a lot of specialists assure that the most acceptable variant is two embryos. One of the reasons for such choice is desire to avoid unnecessary reduction of embryos. In order to reduce the number of multiple pregnancies, authorities of many countries toughen rules according to which in vitro fertilization is carried out. Most foreign clinics prohibit simultaneous implantation of more than two embryos, and under the law of some countries, for example Sweden, it is allowed implanting only one embryo. Today, transfer of more than two embryos is produced mainly at the urgent request of the IVF clinics patients, especially after numerous attemps which did not have positive result.

The reduction of embryos is not just a complex operation, which involves a lot of negative consequences. It is also a serious psychological trauma for the patient, who, of course, can not stop thinking that, giving her consent to the reduction, she is, therefore, agrees to destroy the fetus.