Amniocentesis - Accuracy, Benefits & more Details

Amniocentesis is a test in which a small amount of amniotic fluid is collected from the amniotic fluid to check the health of the baby. This water-like fluid surrounds and protects the fetus. It consists of live fetal cells and other proteins, which give vital genetic information about the fetus. Doctors usually suggest this test when there is a risk of chromosomal abnormality, history of genetic disorders, or any other infections. It plays an important role in reproductive health by detecting issues in early pregnancy.

This Story also Contains

1. What Is Amniocentesis?
2. Why Is Amniocentesis Performed?
3. The Procedure of Amniocentesis
4. Advantages of Amniocentesis
5. Risks and Considerations of Amniocentesis
6. MCQs on Amniocentesis

Amniocentesis is considered as an important diagnostic tool in the field of human reproduction. As much as amniocentesis is helpful, it also raises ethical, and legal concerns. In some countries it has been misused for sex determination. It is closely related to humans. This article talks about what amniocentesis is, procedure, benefits, and risks of amniocentesis.

What Is Amniocentesis?

Amniocentesis is a process done before a baby's birth to detect any development and health abnormalities. In this process, amniotic fluid is taken from the womb of a pregnant woman. It is done using a fine needle. The fluid comprises cells and various proteins that can give doctors important information about the conditions of the fetus. It is typically conducted between the 15th and 20th week of gestation. Some important points about amniocentesis are mentioned below:

• Helps in detecting chromosomal abnormalities such as Down syndrome and other genetic disorders.

• Helps to detect neural tube defects such as spina bifida where the spinal cord does not form properly.

• Certain infections can also be detected.

• Checks if a baby has hemolytic disease (when the mother has Rh-negative and the fetus has RH positive blood).

Why Is Amniocentesis Performed?

Amniocentesis is performed during the second trimester of pregnancy. It is advised by the doctors when there is a risk of any health issues in the unborn baby. The main reasons for performing amniocentesis is:

Detecting Chromosomal Abnormalities

• Such as Down Syndrome, Patau Syndrome, Turner Syndrome, etc.

Detecting Genetic Disorders

• Such as cystic fibrosis, sickle cell anemia, or Tay-sachs disease.

Neural Tube Defects

• Such as spina bifida.

Fetal Lung Maturity

• It helps doctors decide whether early delivery of the baby is safe or not.

Sex Determination

• It is only for medical purposes to identify sex-linked disorders such as hemophilia.

The Procedure of Amniocentesis

Amniocentesis is performed by a trained medical professional. The procedure takes 20-30 minutes. The main step is to collect a sample of amniotic fluid for testing. The step-by-step instructions of how amniocentesis is performed is as follows:

1. Ultrasound - An ultrasound is performed to locate the position of the fetus and the placenta.

2. Preparation - The abdomen of the mother is cleaned with an antiseptic to prevent infection. Anesthesis may be used to numb the area.

3. Fluid Extraction - A thin, hollow needle is inserted into the uterus through the abdominal wall and a small amount of amniotic fluid is extracted.

4. Monitoring - The needle is removed and the mother is asked to rest. Ultrasound is done to ensure there is no immediate complication.

5. Laboratory Testing - The collected fluid is sent to the lab for testing chromosomal abnormalities, human genetic disorders, and neural tube defects.

6. Results - It can be collected within 1-2 weeks and a follow-up visit is scheduled.

Advantages of Amniocentesis

Amniocentesis is considered a reliable and precise test during pregnancy. It allows doctors to understand the health of the baby before birth. Below are some the key advantages:

1. Accurate Information - It provides accurate information about the chromosomal structure and overall genetics of the fetus.

2. Early Detection - It allows parents and doctors to prepare for medical treatment or any other surgical process immediately after birth.

3. Rh Incompatibility - Rh incompatibility can cause anemia or any other infection which can be detected using the test

4. Decision to Continue or Terminate Pregnancy - Based on the test and the fetus's health, the family can make a decision whether to continue or medically terminate the pregnancy.

Risks and Considerations of Amniocentesis

In certain cases, doctors recommend checking the risk of inherited genetic conditions through pedigree analysis. While amniocentesis is generally safe when performed by medical experts. But there are some minor risks involved as it is an invasive process. These include:

1. Miscarriage - The most serious risk is miscarriage. Although it is very rare, about 0.1% to 0.3%. However, the experience of the doctor plays a very vital role in this entire procedure.

2. Infection - There is a slight risk of infecting the mother and fetus during the procedure. This can be due to unsterilised instruments used to perform the procedure.

3. Amniotic Fluid Leakage - A small amount of amniotic fluid may leak due to insertion of the needle. This occurs in about 1% of the cases but often clears on its own.

4. Rh Sensitization - In Rh-negative mothers, fetal blood can enter into the mother's body and cause Rh sensitization (based on Rh blood group system).

5. Cramping and Discomfort - Some mothers experience cramping, or spotting after the procedure, which generally solves within a day or two.

MCQs on Amniocentesis

Q1. Which of the following genetic disorders can be diagnosed by amniocentesis?

1. Down Syndrome

2. Hemophilia

3. Sickle cell anemia

4. All of the above

Correct answer: 4) All of the above.

Explanation:

Amniocentesis is a foetal sex determination and disorder test based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo.This procedure is used to test for the presence of certain genetic disorders such as Down syndrome, haemophilia, sickle-cell anaemia, etc., to determine the survival of the foetus. Amniotic fluid containing cells from the skin of the fetus can be analysed to check the above-mentioned conditions. If it is established that the child is likely to suffer from a serious incurable congenital defect, the mother should get the fetus aborted.

Hence, the correct option is (4) All of the above

Q2. Amniocentesis is used for:

1. chromosomal pattern-based testing for fetal sex and diseases

2. determining eye colour

3. determining blood type

4. predicting height

Correct answer: 1) chromosomal pattern-based testing for fetal sex and diseases

Explanation:

Amniocentesis is a foetal sex determination and disorder test based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo. Based on the chromosomal pattern in the amniotic fluid around the growing embryo, amniocentesis is a medical treatment used to identify the gender of the fetus and detect specific genetic diseases. Amniocentesis is not used to identify a person's blood type, determine their eye colour, or forecast their height.

Hence, the correct option is 1) chromosomal pattern-based testing for fetal sex and diseases.

Q3. At what stage of pregnancy is amniocentesis usually performed?

1. First Trimester

2. Second trimester

3. Third Trimester

4. None of the above

Correct answer: 1) Second Trimester

Explanation:

Amniocentesis is usually performed in the second trimester of pregnancy, typically between weeks 16 and 20. This is because by this time, there is enough amniotic fluid surrounding the fetus to obtain a sample for testing, and the risk of miscarriage from the procedure is lower compared to earlier in pregnancy. However, in some cases, amniocentesis may be performed later in pregnancy if necessary.

Hence, the correct option is 1) Second Trimester.

Also Read:

• MCQs on Amniocentesis

• Medical Termination of Pregnancy (MTP)

• Infertility