1 What is an Amniocentesis?

Amniocentesis is a procedure in which amniotic fluid is removed from the uterus for testing or treatment.

Amniotic fluid is the fluid that surrounds the fetus during pregnancy.

This fluid is composed of fetal cells and various chmicals produced by the baby.

Although amniocentesis can provide valuable information about your baby's health, it is very important to undestand the risks of amniocentesis and be prepared for the results.

2 Reasons for Procedure

Amniocentesis procedure can be done for the following reasons:

Genetic testing

This procedure involves taking a sample of amniotic fluid and testing it for certain conditions such as Down's syndrome.

Fetal lung testing

This procedure invloves taking a sample of amniotic fluid and testing it o determine whether the baby's lungs are mature enough enough for birth.

Diagnosis of fetal infection

In some cases, amniocentesis can be used to evaluate the baby for infection or other illness. It can also be done to evaluate the severity of anaemia in babies who have Rh sesitization (an uncommon condition in which a mother's immune system produces antibodies against her baby).


If you accumulate too much amniotic fluid during the time of pregnancy (polyhydramnios), amniocentesis can be carried out to to drain excess amnitic fluid. 

3 Potential Risks

Potential risk of amniocentesis may include the following:

Leaking amniotic fluid

Rarely, amniotic fluid leaks through the vagina after amniocentesis.


Second-trimester amniocentesis carries a slight risk of miscarriage — about .6 percent. Research suggests that the risk of pregnancy loss is higher for amniocentesis done before 15 weeks of pregnancy.

Needle injury

During amniocentesis, the baby might move an arm or leg into the path of the needle. Serious needle injuries are rare.

Rh sensitization

Rarely, amniocentesis might cause the baby's blood cells to enter the mother's bloodstream. If you have Rh-negative blood and you haven't developed antibodies to Rh positive blood, you'll be given an injection of a blood product called Rh immune globulin after amniocentesis.

This will prevent your body from producing Rh antibodies that can cross the placenta and damage the baby's red blood cells. A blood test can detect if you've begun to produce antibodies.


Very rarely, amniocentesis might trigger a uterine infection. If you have an infection — such as hepatitis C, toxoplasmosis or HIV/AIDS  the infection can be transferred to your baby during the procedure.

Remember, genetic amniocentesis is typically offered when the test results might have a significant impact on the management of the pregnancy.

Ultimately, the decision to have a genetic amniocentesis is up to you. Your health care provider or genetic counselor can help you in making your decision.

4 Preparing for your Procedure

If you are having an amniocentesis performed before the 20th week of pregnancy, it might be very helpful to prepare with your bladder full during the procedure to support the uterus.

You are also required to drink plenty of fluids before the procedure. After week 20 of pregnancy, your bladder should be empty during amniocentesis to minimize the chance of puncture.

Your health care provider will clearly explain the procedure and ask you to sign a consignment form prior to the procedure.

Consider asking a family member or friend to take you along for emotional support or to drive you home afterwards.

5 What to Expect

Amniocentesis is usually done in an outpatient facility or the health care provider's office.

Here’s what you can expect before, during, and after your amniocentesis procedure:

During the procedure

First, your health care provider will use ultrasound to determine the baby's exact location in your uterus. You'll lie on your back on an exam table and expose your abdomen.

Your health care provider will apply a special gel to your abdomen and then use a small device known as an ultrasound transducer to show your baby's position on a monitor. Next, your health care provider will clean your abdomen with an antiseptic.

Generally, anesthetic isn't used. Most women report only mild discomfort during the procedure. Guided by ultrasound, your health care provider will insert a thin, hollow needle through your abdominal wall and into the uterus.

A small amount of amniotic fluid will be withdrawn into a syringe, and the needle will be removed. The specific amount of amniotic fluid withdrawn depends on the number of weeks the pregnancy has progressed.

You'll need to lie still while the needle is inserted and the amniotic fluid is withdrawn. You might notice a stinging sensation when the needle enters your skin, and you might feel cramping when the needle enters your uterus.

After the procedure

After the amniocentesis, your health care provider will continue using the ultrasound to monitor your baby's heart rate. You might experience cramping or mild pelvic discomfort after an amniocentesis.

You can resume your normal activity level after the procedure. However, you might consider avoiding strenuous exercise and sexual activity for a day or two.

Meanwhile, the sample of amniotic fluid will be analyzed in a lab. Some results might be available within a few days. Other results might take up to four weeks.

Contact your health care provider if you have:

  • Loss of vaginal fluid or vaginal bleeding
  • Severe uterine cramping that lasts more than a few hours
  • Fever Redness and inflammation where the needle was inserted
  • Unusual fetal activity or a lack of fetal movement

6 Procedure Results

Your health care provider or a genetic counselor will assist you in understanding your amniocentesis procedure results.

For genetic amniocentesis, test results can rule out or diagnose various genetic conditions such as Down' syndrome.

However, amniocentesis cannot be able to identify all genetic conditions and birth defects.

If amniocentesis indicates that your baby has a chromosomal genetic disorder that cannot be treated, you might face wrenching decisions such as whether to continue the pregnancy.

For fetal lung maturity, amniocentesis tests results can reliably indicate baby's lung maturity.

If you need to deliver the baby ahead of time, this information can offer reassurance that your baby is ready to be born

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