Amniocentesis Test During Pregnancy

6 min read

Various tests and diagnoses are unavoidable in the course of pregnancy to gather relevant information, mainly if the pregnancy goes down under the ‘high risk’ category. These tests reveal several significant issues that affect the normal course (and outcome) of pregnancy and helps to find practical solutions like(if needed) even terminating the pregnancy (if the result of that pregnancy is going to be an unfortunate event) after discussing with the parents. The amniocentesis test is one of such prenatal tests.
amniocentesis test

Why Is Amniocentesis Test Recommended?

Amniocentesis (commonly called amnio) is a prenatal test that helps your doctor to collect the details about your baby’s health by testing the amniotic fluid that surrounds the baby. Fetal cells, chemicals, and microorganisms in the amniotic fluid provide a lot of information regarding the growing baby inside you. Amniocentesis is an essential prenatal diagnostic tool for finding out if the fetus has chromosomal abnormalities (including Down syndrome, neural tube defects such as spina bifida, and genetic diseases such as sickle-cell anemia).

Which Disorders Can Be Detected Through Amniocentesis Test

Amniocentesis is performed to detect several hundreds of genetic disorders and nearly most of the chromosomal abnormalities. The severity, though, cannot be determined precisely by performing this examination. The test can also not detect any structural birth defects, like heart malformations or a cleft lip or palate. Here is the list of 10 most commonly recognized disorders and defects by performing amniocentesis:

  1. Down syndrome/ trisomy 21: Down syndrome, also known as Trisomy 21, is a condition in which additional hereditary material (extra full or partial copy, of chromosome 21) affects the mental and physical development of the baby
  2. Turner syndrome: Turner syndrome is a chromosomal condition that affects only the baby girls (1 in every 2500 girls are found to born with this chromosomal disorder). Partially or entirely missing the X-chromosome is the reason behind this condition. Girls with Turner syndrome appear shorter than average height, and usually, will not attain puberty and will be not able to conceive (infertile), as the ovary will not be functioning
  3. Patau syndrome/Trisomy 13: This is a rare genetic disorder in which the genetic materials of chromosome 13 (all or partially) appear three times. Severe physical and mental impairment is the outcome of this syndrome
  4. Edward’s syndrome/Trisomy 18: This is the most commonly found trisomy syndrome after Down’s syndrome. Here, the baby will have three copies of chromosome 18. Most of the babies get affected, for some reason, baby girls. Most of the babies are not able to survive the second and third trimester of pregnancy. They develop many issues related to organ systems and possess physical deformations
  5. Cystic fibrosis: This is a genetic disorder, which can be fatal, which affects mostly the lungs and digestive system of the baby. Exocrine glands are affected creating thicker mucus and saltier sweat
  6. Tay-Sachs disease: The defective gene of the 15th pair of the chromosome is the reason behind this disease. The baby may seem normal for around three to six months old. Their nervous system becomes progressively damaged, affecting their mental and physical abilities
  7. Spina bifida: Spina bifida is also called a neural tube defect. Here, the bone of the spine will not form properly around the spinal cord. The severity ranges from minor to severe
  8. Anencephaly: Anencephaly is a severe birth defect in which, the baby is born without a major portion of the brain, skull, and the scalp
  9. Sickle cell anemia: Sickle cell anemia is a genetically passed down blood disorder characterized by not having enough healthy RBC to carry oxygen. Normally the blood cells are round and flexible. Whereas in babies with sickle cell anemia, the blood cells will be irregular in shape, rigid and sticky
  10. Muscular dystrophy: Muscular dystrophy is a condition in which the muscle of the body gets progressively weaker and eventually stops working. This condition comes about due to the mutation in X-chromosome
Who Is Recommended For Taking The Amniocentesis Test?

Amniocentesis is typically offered when the pregnancy has an expanded danger of hereditary issues and chromosomal issues. In normal pregnancies, this test will not conduct as the procedure of an amniocentesis includes the presentation of instruments into the womb. One cannot rule out a slight chance of miscarriage. Because some women do end up miscarrying in the second trimester, there is no sure shot way to ascertain whether the unfortunate incident was caused by amniocentesis or not. The risk can further be negated by getting the test done at the hands of an experienced diagnostic sonographer in a reputed clinic. Amniocentesis is generally offered if:

  • The mother delivered a baby with Down syndrome or other chromosomal or hereditary issue in her previous delivery
  • The screening test conducted during the first trimester to determine genetic disorder, together with the follow-up tests that are conducted, turned out to be positive, or show abnormal readings. The screening tests include:
    • Noninvasive prenatal screening tests (NIPT), which is done after the 10th week of pregnancy
    • Chorionic villus sampling (CVS), which is done between 10th to 12th week of pregnancy to rule out or find out the Down syndrome
    • Triple screen which measures three substances [alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol] or quad screen, which measures four substances [estriol, inhibin A, human chorionic gonadotropin (hCG), and alpha-fetoprotein (AFP)] in the mother’s blood, to find if the baby possesses any chance to develop birth defects like Down syndrome
  • If genetic birth defects run in the family
  • Towards the ends of pregnancy, if some medical issue arises which prefer to inducing labor more than two weeks prior to the due date, amniocentesis is conducted to determine whether the lungs of the baby is mature enough to respire
  • If the age of the mother is above 35 years and the screening test results slightly deviate from the norm
  • If the mother is a carrier of a chromosomal disorder connected with the X-chromosome. The baby boys delivered by such mothers have 50% of an increased chance of experiencing that disorder. Hemophilia is an example of such a disorder
When Is The Amniocentesis Test Conducted?

The procedure of amniocentesis is usually scheduled between the 15th and 18th week of pregnancy. Depending on the results of the screening tests conducted earlier, amniocentesis may conduct as early as the 13th or 14th week of pregnancy. It may also be conducted as late as around the 24th week. In the case of membrane rupture, Amniocentesis is also performed at any time during the last trimester. This is to evaluate the uterine infections due to the premature rupture of the membrane. It also determines the severity of fetal anemia. The results helps to decide whether a blood transfusion is necessary to save the life of the baby. It also helps to determine the maturity of the fetal lung.
amniocentesis during pregnancy

What Is The Procedure Of Amniocentesis Test?

The whole process will be completed within 30 minutes. While performing amniocentesis, you have to lie down on your back. The abdomen will be wiped with an iodine solution to prevent any infection. The position of the amniotic sac, placenta, and the fetus is located by performing ultrasound simultaneously with the procedure. The slight danger of unintentionally pricking the embryo amid this procedure is further lessened by the utilization of ultrasound side by side. Though the abdomen can be numbed with an injection, most of the doctors will not prefer that, as there is no significant difference between the pain of injection and pain of the insertion of the needle. Both are somewhat the same. Therefore, there is no point in experiencing pain twice. Moreover, the needle part will be over within two minutes. However, if the patient insists, the abdomen is temporarily numbed before starting the procedure as the mother feels sharp pain twice (first when the needle pierces the skin and the second time when it enters the uterus). If the mother belongs to the Rh-negative group, after amniocentesis, Rh-immune globulin injection is given to the mother. This will avoid possible issues with the Rh factor.

What Are The Risks Of Conducting Amniocentesis Test?

An experienced registered diagnostic medical sonographer conducts amniocentesis. It also has continuous ultrasound guidance throughout the procedure. Even then, as it is an obtrusive analytic test, amniocentesis does have a few risks.

  1. Miscarriage: Miscarriage is the most common risk that is related to amniocentesis. The risk of miscarriage due to amniocentesis performed during the second trimester is very low. Whereas, when when the amniocentesis is performed before the 15th week of pregnancy, the chance of pregnancy loss increases. However, the overall possibility is very low as it ranges from 1 in 500 to 1 in 200
  2. Injury: The odds of the baby having a minor needle injury are quite low. However, the baby might get a needle injury if its arms or legs suddenly come into the needle’s way. The chances of serious injuries are rare
  3. Spotting and fluid leakage: Though on rare occasions, amniotic fluid is found to leak (through the vagina) after amniocentesis. Anyhow, mostly, the amount of fluid loss is very low and will cease within a week without affecting the normal progress of the pregnancy. The spotting will also stop eventually if proper rest is taken without affecting the pregnancy
  4. Infection: Though not often, amniocentesis is found to set off a uterine infection in some cases
  5. Cramps: Cramps similar to slight menstrual cramps and discomfort can be experienced for some time after the procedure of amniocentesis

You should contact your doctor and seek medical attention immediately if you experience fever, increased vaginal discharge (more than minor spotting), or abdominal pain, which is severe than slight cramps.

What Happens If It Is Found That My Baby Has A Problem?

In such a scenario, genetic counseling is mostly offered to provide you more information regarding the problem and discuss the options. You may decide to continue or terminate the pregnancy. Many support groups exist in both the online and offline spaces, and some women may find them helpful. Whatever you choose, you can opt for further counseling and seek support.

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