What is Amniosentesis? - Health Care

What is Amniocentesis: Overview, Benefits, and Expected Outcomes

What is Amniosentesis?

Amniocentesis is a procedure to test for amniotic fluid (amnio) present in a pregnant woman's uterus. This procedure is also known as the amniotic fluid test. Used for diagnosis and examination, amniocentesis is only performed when severe fetal disorders are found. This procedure can detect chromosomal abnormalities and congenital defects as well as diagnose diseases. However, this procedure is also risky, so doctors will strongly consider the benefits and dangers of amniocentesis before suggesting it to patients.

Who Needs to Undergo Amniocentesis and Expected Outcomes

Amniocentesis is a particular diagnostic test that is only performed if:

• It is suspected that there is a high risk of fetal abnormalities or congenital defects.
• Placental membranes perforated too early.

One indication of both is the abnormal results of a triple test, a routine blood test to measure AFP, hCG, and Estriol levels. All three are substances produced by the body during pregnancy.

• AFP, or alpha-fetoprotein, is a protein produced by the fetus.
• hCG, or human chorionic gonadotropin, is a hormone produced by the placenta.
• Estriol, the hormone estrogen produced by the fetus and placenta

If the triple test gives abnormal results, the doctor may recommend that the patient undergo amniocentesis to examine amniotic fluid around the fetus. The purpose of this procedure is:

• Detect chromosomal abnormalities, such as Down syndrome. And other syndromes like Edwards and Turner.
• Detect neural tube defects, such as spina bifida  or anencephaly
• Diagnosing genetic disorders, such as cystic fibrosis
• Diagnosing congenital metabolic disorders
• Knowing the sex of the fetus
• Detecting fetal or uterine infections
• Diagnosing Rh disease
• Assess the severity of fetal  anemia
• Knowing the baby's father through DNA testing (fetal DNA can be found in amniotic fluid)
• Assessing the growth and development of fetal lungs is one reason why amniocentesis will be needed in the third trimester or shortly before the estimated day of birth.

The test is 99% accurate for detecting chromosomal abnormalities, neural tube defects, and genetic abnormalities. This test is equally precise in testing DNA. The only thing that cannot be known with this test is the severity of the congenital defect. Therefore, the patient will need additional tests, including ultrasound.

Often, amniocentesis can help determine whether the fetus will need treatment. For example, if there is a neural tube defect, parents may consider fetal surgery. If there is a genetic disorder, parents can also know the baby's unique needs and prepare for them early.

How Amniocentesis Works

Amniocentesis is done in a specialist obstetric clinic or hospital. This procedure is usually performed in the second trimester of pregnancy or when the fetus is 15-20 weeks old. Although rare, amniocentesis can also be done earlier. The maximum limit is at the age of 11-13 weeks because it can increase the risk of fatal injury if it is too early. Usually, this procedure does not need to be done again in the third trimester.

The doctor will take fluid from the amniotic sac during the test by injecting a needle into the uterus through the patient's abdomen. The amount of amniotic fluid needed is about 20 ml. Before the test, the patient will undergo an ultrasound so that the doctor can know the safest point for injection.

The process of taking fluids only takes 5 minutes. However, the entire test process can take up to 45 minutes, including ultrasound and other preparations.

A sample of the liquid will be sent to a laboratory for analysis. The results can be obtained in a few days or weeks and explained to patients during follow-up consultation with an obstetrician.

Possible Complications and Risks of Amniocentesis

Amniocentesis is an invasive procedure that can harm both mother and baby. Therefore, this procedure will only be done when needed.

Some of the risks of amniocentesis are:

• Uterine infection
• Amniotic water breaks
• Premature birth
• Difficulty breathing
• Skeletal abnormalities in infants
• Trauma to the fetus
• Rhesus disease, or alloimmunization in the mother
• Miscarriage

Amniocentesis can also cause pain when a needle is injected into the skin and penetrates the uterus. If needed or requested by the patient, the doctor may give a local anesthetic before the procedure. A sonogram will also be used to make sure the needle doesn't hit the fetus.

After amniocentesis, the mother can secrete amniotic fluid, stomach cramps, and slight discomfort in the injecting area.

The fetus will not be affected by the procedure because the amniotic sac will close the injection marks and restore the amount of amniotic fluid within 24-48 hours.

Although at risk, amniocentesis is considered safer than chorionic virus sampling, another test that detects chromosomal and genetic abnormalities.

Before undergoing amniocentesis, a pregnant woman should discuss and consider the benefits and risks with an obstetrician. In some countries, the limitations of these tests are governed by law.

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