Preimplantation genetic diagnosis (PGD or PIGD), is the genetic testing of embryos before the process of implantation. In some cases, it may also refer to the screening of eggs before fertilization. It is mainly used in in-vitro fertilization (IVF) to identify the presence of genetic defects in the embryo. It is different from preimplantation genetic screening (PGS) in the sense that PGS is done in embryos even when none of the parents has any genetic abnormalities while PGD is done if one or both the parents have a genetic abnormality and there is a risk of passing it on to the child.
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How is it done?
PGD is a part of the IVF process. The steps involved are:
- Initially, the normal IVF process is done which consists of stimulating ovaries by administering synthetic hormones leading to an increased number of eggs. The eggs are then collected at the time of ovulation.
- At the same time, the sperm sample is also collected. If there is some complication associated with sperm collection or condition like azoospermia, then the sperm may be retrieved manually by various sperm retrieval techniques.
- Then the fertilization is done in the laboratory by placing an egg in between thousands of sperm cells.
- The embryos are then allowed to grow by cell division for about five days.
- Then a few cells are collected from each embryo and the embryos are then frozen.
- The DNA of cells from each particular embryo is then evaluated for the presence of genes which may lead to genetic abnormalities. This process usually takes more than a week.
- The embryos which are free from genetic problems are then transferred inside the uterus. The remaining embryos without genetic problems are further frozen for any future use. The embryos carrying genetic abnormalities are usually destroyed.
PGD is a time-consuming process as it involves various steps from ovary stimulation to DNA testing and implantation.
Who should opt for it?
Broadly speaking, couples at high risk of passing genetic conditions to the baby are probable candidates for PGD. This includes:
- Carriers of sex-linked genetic disorders
- High risk of single gene disorders
- Single or both the parents having chromosomal disorders
- If the age of the woman at the time of conception is 35 or more
- Women with repeated fertility treatment failure
- Women experiencing repeated failed pregnancies
Benefits of PGD:
Preimplantation genetic diagnosis offers the following benefits:
- PGD can effectively be used to test hundreds of genetic conditions.
- It enables the couple to make a more informed decision about the pregnancy. The couple has ample time and information to decide if they wish to go ahead with pregnancy or not.
- It helps in selectively choosing the best embryo with minimal risks associated and discarding embryos carrying genetic abnormalities.
PGD is a very effective option for couples with genetic abnormalities or those having a risk of passing abnormalities on to their children. Though it is not possible to detect all the genetic abnormalities, a large number of risks can be successfully eliminated.
To Know More: ABOUT PREIMPLANTATION GENETIC SCREENING
At Cloudnine, we completely understand how important and special the journey of pregnancy and childbirth is. To enable you to make better and informed decisions about pregnancy, we provide you with a wide range of facilities and services including assisted reproductive technology (ART) and preimplantation genetic diagnosis. Our highly qualified and experienced experts are dedicated to providing you with the best possible treatment and care.