Question

The prenatal genetic screening method that tests cells attaching the pregnancy sae to the wall of the uterus is called a. chorionic villus sampling (CVS). b. amniocentesis. c. preimplantation genetic diagnosis (PGD). d. in vitro fertilization.

Short answer

a. chorionic villus sampling (CVS).

Step-by-step solution

Understand the Keywords

Identify the primary terms in the problem: 'prenatal genetic screening method', 'tests cells', 'pregnancy sac', and 'wall of the uterus'.

Identify Each Option

Look at each option and understand what each procedure tests and how it relates to the keywords.

Analyze Chorionic Villus Sampling (CVS)

Chorionic Villus Sampling (CVS) involves taking a sample of some of the placental tissue, which contains the same genetic material as the fetus. The sampling is done via the cervix or the abdominal wall.

Analyze Amniocentesis

Amniocentesis involves testing the amniotic fluid surrounding the fetus for genetic abnormalities.

Analyze Preimplantation Genetic Diagnosis (PGD)

Preimplantation Genetic Diagnosis (PGD) is conducted on embryos created through in vitro fertilization before they are implanted in the uterus.

Analyze In Vitro Fertilization

In Vitro Fertilization (IVF) is a process of fertilizing an egg outside of the body. It does not involve direct genetic testing in the uterus.

Choose the Correct Answer

From the analysis, chorionic villus sampling (CVS) tests cells from the pregnancy sac which is attached to the wall of the uterus.

Key concepts

Chorionic Villus Sampling (CVS)

Chorionic Villus Sampling (CVS) is a prenatal genetic screening method that involves taking a small sample of tissue from the placenta. The placenta contains the same genetic material as the fetus, making it a reliable source for genetic testing. CVS can identify chromosomal abnormalities and other genetic disorders early in pregnancy. It is typically performed between 10 and 13 weeks of gestation.
The procedure can be done in two ways:

• Transcervical: A thin tube is inserted through the cervix to reach the placenta.
• Transabdominal: A needle is inserted through the abdominal wall to collect the sample.

Certain risks include miscarriage, infection, and Rh sensitization. However, providing valuable early information about the baby's health can help parents make informed decisions.

Amniocentesis

Amniocentesis is another type of prenatal genetic screening test but it is generally conducted later in pregnancy compared to CVS, usually between 15 and 20 weeks of gestation. This procedure involves drawing a small amount of amniotic fluid, which surrounds the fetus, using a fine needle inserted into the uterus through the abdominal wall.
The fluid contains fetal cells and various chemicals that can be analyzed for genetic conditions, chromosomal abnormalities, and infections.

• Detects: Down syndrome, spina bifida, and other physical or genetic conditions.
• Risk: Similar to CVS, it carries risks of miscarriage, needle injury, and infection.

However, it is highly accurate and provides a lot of valuable information about the fetus’s health.

Preimplantation Genetic Diagnosis (PGD)

Preimplantation Genetic Diagnosis (PGD) is not the same as CVS or amniocentesis because it is done before pregnancy even begins. PGD is integrated into the process of In Vitro Fertilization (IVF).
During PGD, embryos created through IVF are tested for genetic or chromosomal disorders before being implanted into the uterus.

• Procedure: A few cells are taken from each embryo after 3 to 5 days of development.
• Benefit: Only embryos without genetic issues are chosen for implantation.

This method significantly reduces the risk of genetic diseases and abnormalities in the baby, offering parents a way to ensure the health of their future child before pregnancy.

In Vitro Fertilization (IVF)

In Vitro Fertilization (IVF) is a complex series of procedures used to assist with the conception of a child. It involves retrieving eggs from a woman's ovaries and fertilizing them with sperm in a laboratory. The fertilized egg, or embryo, is then transferred to the uterus.

• Steps in IVF:
  • Ovarian Stimulation: Hormones are given to stimulate multiple egg production.
  • Egg Retrieval: Eggs are taken from the ovaries using a needle.
  • Fertilization: Sperm and eggs are combined outside the body.
  • Embryo Transfer: Healthy embryos are placed in the uterus.
• Broken Down Simply: Stimulate, retrieve, fertilize, and implant.

IVF is often used by couples who have trouble conceiving and can be combined with PGD to screen for genetic conditions.