What is Amniocentesis?

Amniocentesis is a medical procedure during which amniotic fluid is extracted and analyzed to examine a baby’s chromosomes.

This amniotic fluid consists of cells, proteins, and fetal urine, which can all be analyzed to obtain information about the baby’s health.

In general, amniocentesis is done between 16 and 20 weeks of pregnancy, and is recommended for women giving birth at 35 years of age or older.

During the procedure, amniotic fluid is extracted in order to be analyzed. The amniotic fluid contains cells that the baby naturally sheds.

The cells and proteins in this fluid are examined in a laboratory in order to detect the presence of specific fetal disorders. This fluid also contains alpha-fetoprotein (AFP), which can be measured in a lab.

The appointment for an amniocentesis lasts approximately 45 minutes, and the majority of the time is spent performing a detailed ultrasound.

Why undergo an amniocentesis?

This exam has an accuracy rate of over 99% for the diagnosis of Down syndrome. It can also be used to diagnose many different genetic and chromosomal problems in the baby, including Anencephaly (when the baby is missing a large portion of the brain).

The exam is also used to detect unusual metabolic disorders that are passed down from parents to children, as well as other genetic problems, such as trisomy 18.

An amniocentesis can also determine whether the baby is suffering from a malformation of the neural tube, such as Spina bifida, or certain metabolic diseases.

Additionally, the exam allows for the detection of uterine infections and helps to determine the severity of fetal anemia. The volume of fluid extracted depends on the tests that are going to be run.

An alternative to amniocentesis

Gynecologists now offer an alternative to the removal of amniotic fluid through blood tests called Maternal Blood Screening Tests.

This test assesses the probability of a baby being born with Down syndrome, Edwards syndrome, or Patau syndrome, as well as the absence or presence of extra chromosomes. The sex of the baby can also be determined.

The bond that links your true family is not one of blood, but of respect and joy in each other’s life.

–Richard Bach, American writer–

The problem with this test, in contrast to amniocentesis, is the reliability of the results. It is true that the sensitivity of this test is greater than that of Triple Screening, but in no case is it a diagnosis. For this reason, amniocentesis is much more complete, exact, and reliable.

Generally, women feel ambivalent about the exam: they would like to know the information that an amniocentesis could provide, but they don’t want to put their baby at risk.

For this reason, specialists recommend that before deciding whether or not to go through with the exam, the mother and father should weigh the consequences of a Down syndrome result. 

What does an amniocentesis consist of?

When a woman 35 years of age or older undergoes an amniocentesis exam, a specialist extracts a small amount of the sac that surrounds the baby and contains amniotic fluid.

In order to do so, the specialist inserts a long, thin needle through the abdomen into the uterus and takes a small sample of fluid, all while observing an ultrasound to guide the needle.

This is a quick and relatively painless exam, and one that is necessary at a certain age, because as the pregnant woman’s age increases, the probability that the baby will be born with chromosomal alterations also increases.

Still, many pregnant women around the world fear undergoing this exam because it has been linked to the risk of fetal loss, since it has been proven that amniocentesis increases the rate of spontaneous miscarriage.

The most recent data shows that approximately one in every 1,600 women may suffer a miscarriage as a result of amniocentesis. However, it does remain the most reliable test.

Specialists insist this is not a painful procedure. So far, we’ve seen that only a few women experience minimal discomfort with the prick of the needle. Others experience mild cramping during and after the procedure, but this usually passes quickly.

Cramps generally go away within an hour after the procedure, but may occur again periodically for one or two days following the amniocentesis.

Some women may also experience abdominal pain at the site of needle insertion, which usually goes away within a few hours, but may also last for several days.