Pregnancy and Amniocentesis

Medically Reviewed by Dr. K on 21 April 2021

Table of Contents :

  1. What Is Amniocentesis?
  2. Why Is an Amniocentesis Performed? 
  3. When Is Amniocentesis Performed? 
  4. How Accurate Is Amniocentesis? 
  5. Does Amniocentesis Have Risks? 
  6. Can I Choose Not to Have an Amniocentesis? 
  7. What Happens During an Amniocentesis? 
  8. Can I Resume Normal Activities After an Amniocentesis? 
  9. When Should I Call My Doctor After an Amniocentesis? 
  10. When Will I Receive the Results of the Amniocentesis?


The embryo is surrounded by amniotic fluid, which is similar to water, during pregnancy. Live fetal cells and other compounds, such as alpha-fetoprotein, are found in amniotic fluid (AFP). These compounds will tell you a lot about your baby's well being before he or she is born.


What Is Amniocentesis?

Amniocentesis is a pregnancy test that involves removing a limited volume of amniotic fluid from the sac containing the embryo. Under ultrasound instruction, a small sample of amniotic fluid (less than one ounce) is removed using a fine needle inserted through the uterus via the belly. After that, the fluid is submitted to a laboratory for testing. Based on the genetic vulnerability and the test's signal, several testing will be done on a sample of amniotic fluid.


Why Is an Amniocentesis Performed?

Prior to amniocentesis, a full anatomical ultrasound will be performed. However, amniocentesis is used to check for specific birth abnormalities, such as Down syndrome, which is a chromosomal abnormality. 


Since amniocentesis is a low-risk procedure for both the mother and the infant, it is usually recommended for women who are at high risk for genetic diseases, such as those who:

  • Have had an irregular ultrasound or lab results?
  • Have a background of birth defects in the family?
  • Have ever lost a newborn or been pregnant with a child that was born with a birth defect?
  • Have had an irregular genetic test in the current pregnancy.


While amniocentesis does not diagnose all birth defects, it may be used to detect the following conditions if the parents are genetically predisposed:

  • Down syndrome
  • Sickle cell disease
  • Cystic fibrosis
  • Muscular dystrophy
  • Tay-Sachs and similar diseases


Spina bifida and anencephaly are examples of neural tube disorders (diseases in which the brain and spinal column do not form properly). 


Since ultrasound is done at the same moment as amniocentesis, it will spot birth abnormalities that amniocentesis cannot (such as cleft palate, cleft lip, club foot, or heart defects). However, there are several birth abnormalities that neither amniocentesis nor ultrasound can diagnose. 


You may inquire to find out the baby's gender through an amniocentesis; amniocentesis is the most definitive method to decide the baby's gender before delivery. You can, though, already know the gender of the baby based on an ultrasound or genetic test. 


An amniocentesis may decide whether the baby's lungs are mature enough for birth or to test the amniotic fluid for infection, but it's rarely done in the third trimester.


When Is Amniocentesis Performed?


The procedure is normally planned between the 15th and 18th week of pregnancy if your doctor has prescribed it.


How Accurate Is Amniocentesis?

Amniocentesis has a 99.4% success rate. 


Amniocentesis will sometimes fail due to technical issues, such as not being able to extract enough amniotic fluid or the extracted cells failing to mature when cultured.

Does Amniocentesis Have Risks?


Yes, indeed. An amniocentesis has a slim chance of causing a miscarriage (less than 1%, or approximately 1 in 1000 to 1 in 43000). Other possible risks include injury to the infant or mother, infection, and preterm labour, both of which are very uncommon.


Can I Choose Not to Have an Amniocentesis?


Yes, actually. Before the treatment, you can receive genetic counselling. You will decide whether or not you want to have amniocentesis after the complications and advantages have been fully clarified to you.


What Happens During an Amniocentesis?


To brace for the amniocentesis, a specific region of the abdomen is cleansed with an antiseptic. To alleviate the suffering, you might be given a local anaesthetic (pain-relieving medication). An ultrasound is used to identify the location of the foetus and placenta. A small, hollow needle is inserted across the abdomen and uterus, and into the amniotic sac, away from the foetus, under ultrasound direction. Via the needle, a tiny volume of fluid (less than an ounce) is removed and submitted to the lab for examination. 


During the amniocentesis or for a few hours thereafter, you can have mild menstrual-like cramping or pain.


Can I Resume Normal Activities After an Amniocentesis?


It's better to rest right after an amniocentesis and sleep for the rest of the day. You should not workout or engage in any strenuous activity, lift any heavy items (including children), or engage in sexual intercourse. 


To ease pain, take two paracetamols regularly, as per manufacturer's guidelines. Once you get your doctor's approval, you can restart all of your usual activities the next day.


When Should I Call My Doctor After an Amniocentesis?


If you have a fever, bleeding, vaginal discharge, or abdominal pain that is more intense than cramps, call the doctor.


When Will I Receive the Results of the Amniocentesis?

The amniocentesis findings are usually accessible within 2-3 weeks. Contact the healthcare professional if you haven't got your reports in 3 weeks.


Referenced on  10.4.2021

  1. Amniocentesis. (2019).
  2. Amniocentesis. (2019).
  3. Carlson LM, et al. (2017). Prenatal diagnosis: Screening and diagnostic tools. DOI:
  4. Connolly KA, et al. (2016). Amniocentesis: A contemporary review. DOI:
  5. Prenatal testing for Down syndrome. (n.d.).  
  6. Sadlecki P, et al. (2018). Why do patients decline amniocentesis? Analysis of factors influencing the decision to refuse invasive prenatal testing. DOI:

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