Differences between pre-implantation diagnosis (fertilized egg diagnosis) and prenatal diagnosis, and the benefits, problems, and costs [supervised by a doctor]

What is preimplantation diagnosis (fertilized egg diagnosis)?

Preimplantation diagnosis is a medical procedure in which genetic testing is performed on fertilized eggs artificially fertilized outside the body, and embryos with a low possibility of chromosomal abnormalities are selected and transplanted into the uterus. This test is often mistaken for prenatal diagnosis, but preimplantation diagnosis is performed before pregnancy (before implantation), while prenatal diagnosis is a chromosomal test performed after pregnancy (after implantation).

The world’s first pregnancy resulting from preimplantation diagnosis was reported in 1990, and in Japan, preimplantation diagnosis for serious genetic diseases was approved and implemented in 2004.

In 2018, clinical research into preimplantation diagnosis was completed, and preimplantation diagnosis is now positioned as a medical procedure. In 2022, some infertility treatments will be covered by insurance, and there are plans to introduce preimplantation diagnosis as part of the scope of coverage under public health insurance.

Additionally, in March 2021, the Ministry of Health, Labor and Welfare convened a specialist committee to consider the future of NIPT (non-invasive prenatal testing), a type of prenatal testing. With the proposal for a new certification system in which the government would be involved in reviewing NIPT (non-invasive prenatal testing) facilities and medical institutions, it is expected that the number of facilities that perform prenatal testing, including preimplantation testing and NIPT (non-invasive prenatal testing), will increase.

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Purpose and target population of preimplantation genetic testing

The purpose of preimplantation diagnosis is to reduce the miscarriage rate and improve the pregnancy continuation rate for infertile couples. However, not all infertile couples are eligible for preimplantation diagnosis. In Japan, sex selection through preimplantation diagnosis is prohibited.

Preimplantation diagnosis is a medical procedure that can only be performed on eligible individuals after individual screening by the Japan Society of Obstetrics and Gynecology.

• Carriers of genetic mutations and chromosomal abnormalities that may result in the birth of a child with a serious genetic disorder
• Two or more previous miscarriages (including recurrent miscarriages) thought to be due to balanced chromosomal abnormalities

Preimplantation diagnosis can only be performed if one of the above conditions is met, the couple has a strong desire to undergo it, and there is an agreement between the couple. In addition, the severity of the condition that is eligible for preimplantation diagnosis is defined as “a condition that significantly impairs daily life or puts life in jeopardy before reaching adulthood.”

However, in 2021, the Japan Society of Obstetrics and Gynecology announced proposed changes to the definition of severity.

Previous definition of severity for preimplantation genetic testing

” A condition that seriously impairs daily life or puts life at risk before reaching adulthood “

Proposal for amending the “Definition of Severity” for Preimplantation Genetic Diagnosis

“A condition in which symptoms that severely impair daily life appear or life becomes endangered, for which there is currently no effective treatment to avoid this or for which advanced and highly invasive treatment is required ” (as of February 2021)

Since the previous requirement that preimplantation diagnosis be performed “by adulthood” has been removed, this means that the scope of those who can undergo preimplantation diagnosis will be expanded in the future.

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What are the benefits of preimplantation genetic testing?

There are three main benefits to preimplantation diagnosis:

• Improve the chances of healthy pregnancy and childbirth for couples who are at high risk of inheriting genetic diseases
• Since it is performed during pregnancy (before implantation), it tends to reduce the mental and physical burden on the mother.
• There is no risk of direct damage to the fetus, as with amniocentesis or chorionic villus sampling.

Minimize the risk of transmitting genetic diseases to the fetus

Preimplantation diagnosis is a medical procedure in which embryos with a low risk of developing genetic diseases are selected and transferred to the uterus by performing genetic testing on the embryo before implantation. The greatest benefit of preimplantation diagnosis is that it increases the chances of a healthy pregnancy and birth for couples who are likely to inherit genetic diseases to their fetus without having to give up on having a child.

Reducing the physical and mental damage to the mother caused by miscarriage

Two consecutive miscarriages are called “recurrent miscarriages,” and three or more miscarriages are called “habitual miscarriages.” Repeated miscarriages are believed to be caused by chromosomes in one of the couples, and no effective treatment has been established. The risk of miscarriage also increases with age, and the main cause is chromosomal abnormalities in the fetus.

Since PGD screens embryos with chromosomal abnormalities before implantation (pregnancy), it can be said that the risk of miscarriage caused by chromosomal abnormalities is reduced. For these reasons, PGD is said to tend to reduce the physical and mental damage to the mother caused by miscarriage.

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Problems with preimplantation genetic testing

Not everyone can take PGD. Even if you are a candidate for PGD, there are some issues you should be aware of before taking it.

• Application and approval required from the Japan Society of Obstetrics and Gynecology
• It takes about six months from application to approval.
• Preimplantation diagnosis only checks for certain diseases, so the diagnosis is not 100% reliable.

Application and approval required for preimplantation diagnosis

The Importance of Preimplantation Diagnosis Based on Clinical Research and the Approval Process
In order to undergo preimplantation diagnosis, an application and approval from the Japan Society of Obstetrics and Gynecology is required. With preimplantation diagnosis, embryos without chromosomal abnormalities are selected from multiple embryos and then transplanted into the uterus. Embryos with abnormalities are discarded, and many people fear that this selection leads to the selection of life, the selection of only genetically superior organisms, and eugenics.

For these reasons, the Japan Society of Obstetrics and Gynecology checks each case one by one and manages them strictly. Also, because preimplantation diagnosis requires testing and multiple counseling sessions, it is said that it takes about six months from application to approval by the Japan Society of Obstetrics and Gynecology.

Preimplantation genetic testing requires advanced medical technology and a high level of ethics. Therefore, only facilities certified by the Japan Society of Obstetrics and Gynecology can perform preimplantation genetic testing.

Please be aware that it will take some time after consulting with a medical institution before you can receive preimplantation diagnosis.

The results of PGD are not 100% reliable

PGD ​​is a test to check for specific serious genetic diseases. Therefore, even if the targeted disease is not present, there is a good chance that the fetus may have other chromosomal abnormalities or congenital diseases. In addition, the results of PGD are not 100% accurate, so even if pregnancy and childbirth are achieved through PGD, there is a possibility that a child with a genetic disease will be born.

Flow of Preimplantation Diagnosis

Preimplantation diagnosis is carried out as follows:

1. General Inspection
2. Genetic counseling (multiple times)
3. Preimplantation diagnosis 1: In vitro fertilization
4. Preimplantation diagnosis 2) Genetic testing
5. Preimplantation diagnosis 3. Embryo transfer

1. General Inspection

At a medical institution certified by the Japan Society of Obstetrics and Gynecology that performs preimplantation diagnosis, you will be interviewed and examined to determine whether you are a candidate for preimplantation diagnosis.

2. Genetic counseling

Genetic counselling is a type of counselling that addresses concerns and questions about genetics and provides scientifically based information about genetics.

It is performed multiple times by a genetic medicine specialist at a third-party institution other than the facility that performs preimplantation diagnosis. Since genetic counseling is a so-called second opinion, it is a self-paid medical treatment and the cost varies depending on the facility.

*As of 2018, genetic testing for certain genetic diseases will be covered by insurance.

3. Preimplantation diagnosis ① In vitro fertilization

After receiving approval from the Japan Society of Obstetrics and Gynecology, we move on to preimplantation diagnosis. Eggs and sperm are collected and in vitro fertilization is performed. There are two methods of in vitro fertilization: in vitro fertilization, in which sperm are sprinkled on eggs collected in a petri dish to allow natural fertilization, and microscopic fertilization, in which sperm are directly injected into the eggs while observing them under a microscope.

4. Preimplantation diagnosis ② Genetic testing

Cells are extracted from the embryo that has divided into cells from the fertilized egg, and chromosome and genetic testing is performed.

5. Preimplantation diagnosis 3. Embryo transfer

Genetic testing reveals no chromosomal or genetic abnormalities, and embryos that are likely to be normal are transferred into the uterus.

Preimplantation diagnosis is expensive

Up until now, all preimplantation diagnosis has been a self-paid treatment, and although it varies depending on the medical institution, it is said to be about 500,000 to 1 million yen. Depending on the local government, subsidies may be available, but the burden is not small. Also, a single preimplantation diagnosis does not necessarily produce the desired results, and there may be cases where preimplantation diagnosis is required again.

However, in 2018, genetic testing for certain hereditary diseases became eligible for insurance coverage, and preimplantation diagnosis will be included in the proposed revision to partial insurance coverage for infertility treatment in 2022, so the cost of preimplantation diagnosis may be reduced in the future.

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NIPT (non-invasive prenatal testing) to prepare for risks that cannot be detected by preimplantation diagnosis

Risk assessment based on clinical research and the importance of NIPTPreimplantation
diagnosis can only detect certain genetic diseases. However, there are many different types and symptoms of chromosomal abnormalities and congenital diseases. For these reasons, even if pregnancy is established through preimplantation diagnosis, the risk of miscarriage due to other chromosomal abnormalities cannot be said to be zero.

Hiro Clinic NIPT ‘s NIPT (new type prenatal diagnosis) is a whole chromosome aneuploidy test that can test for abnormalities (aneuploidies) in the numbers of chromosomes 1 to 22 and all sex chromosomes.

Hiro Clinic NIPT is a NIPT (new type prenatal diagnosis) facility that values ​​the “right of mothers and their families to know” above all else . There are no restrictions on the age of pregnant women or whether partners must be present, and anyone can detect the possibility of a baby’s chromosomal abnormalities or congenital disease risk from 10 weeks and 0 days of pregnancy.

NIPT (new type prenatal testing) can be performed using only maternal blood, and for trisomy 21 (Down syndrome), it has a sensitivity and specificity of 99.9%, making it a highly accurate prenatal test.

At Hiro Clinic NIPT , we offer a variety of NIPT (new type prenatal testing) plans, from individual tests that check the risk of a single chromosomal abnormality to whole chromosomal aneuploidy tests that check all chromosomes .

If you are a mother who wishes to undergo preimplantation diagnosis but finds it difficult to apply or get approval, or if you are worried about your baby’s chromosomal abnormalities or congenital diseases, please consult with Hiro Clinic NIPT about NIPT (non-invasive prenatal testing) . Our experienced doctors are well versed in NIPT (non-invasive prenatal testing)
and will answer your questions sincerely. We will help you undergo the test with peace of mind, providing you with the latest information based on clinical research and after-sales support.

(At Hiro Clinic, we use this information as clinical research data with the customer’s consent.)

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Experience unparalleled excellence in Non-Invasive Prenatal Testing (NIPT) at Hiro Clinic. Our world-class services blen...