What is Amniocentesis?
Amniocentesis, also referred to as an amniotic fluid test, or simply an “amnio”, is a prenatal procedure used to collect a small amount of the amniotic fluid that surrounds the baby in the uterus. The collected amniotic fluid contains cells shed by the developing baby and each of these shed cells contains a complete set of the baby’s DNA. The cells can be cultured and the DNA analyzed in order to detect and identify certain potential health problems the fetus may have.
The most common reason for having an amniocentesis is to allow early detection of certain genetic disorders or chromosomal abnormalities in the developing fetus. While an “amnio” can detect hundreds of genetic abnormalities, the most common abnormalities tested for are Down Syndrome (Trisomy 21) and Edward’s Syndrome (Trisomy 18). Also, neural tube defects, which are problems with the formation of a baby’s central nervous system such as spina bifida and anencephaly, can be detected with an amniotic fluid test.
The test is usually performed early enough in the pregnancy (between the 15th and 20th weeks) in order to provide the parents with time to consider their options should serious abnormalities be discovered. In some cases when a serious genetic disorder is discovered, the parents can choose to terminate the pregnancy or they may decide to continue it. It is important to realize that having an amniocentesis in no way obligates you to terminate the pregnancy if an abnormality is discovered. For some conditions, simply having a clear diagnosis can better prepare you and your physicians for taking care of a baby with special needs before and after birth.
Also, in cases where an early delivery is being considered due to medical reasons, your obstetrician may perform an “amnio” to determine the maturity of the baby’s lungs. Amniocentesis can also be used to diagnose a uterine infection, determine the gender of the baby or to evaluate any significant health issues that can arise when the mother’s blood type is different from the baby’s. (see Rh sensitization)
What is Involved?
A local anesthetic may or may not be given before the actual procedure. While you are lying down, your doctor will locate a pocket of amniotic fluid a safe distance from the baby using ultrasound. The doctor then inserts a syringe into the amniotic sac around the baby and a small amount of amniotic fluid is drawn for testing. The whole procedure takes only a few minutes.
After the procedure is performed, your doctor or nurse will watch for any uterine contractions or fetal distress while you rest for 15 – 45 minutes before leaving. It is suggested that you take it easy for the remainder of the day so be sure to arrange for someone to drive you home. Heavy lifting, intercourse, and air travel should be avoided for the next 48 -72 hours. It can take 1 – 2 weeks for the collected cells to be cultured and the results of the test diagnosed.
If you are interested in learning more about amniocentesis or you would like to schedule an appointment to have an amniocentesis performed, please contact Health Care For Women at our Salinas office or by filling out a Quick Contact on their website at www.hcfw.com
Who Should Be Tested?
All pregnant women are candidates for amniocentesis. Since the risk of having a baby with a chromosomal disorder can be relative to age of the mother, amniocentesis is routinely suggested to all pregnant women over the age of 35. Women who previously have had a child with a genetic abnormality or have a family history of certain birth defects, are also suggested to undergo an amniotic fluid test.
Amniocentesis increases the risk of miscarriage by less than 1 percent over the baseline risk for miscarriage. Amniocentesis does not increase the risk of birth defects.
For patients who want information about their risk of birth defects, there are three main alternatives to amniocentesis.
The first is ultrasound, which is done routinely for all pregnancies. Ultrasound can detect some but not all types of birth defects and is less specific for the diagnosis of some syndromes. Routine ultrasounds for this purpose are done between 18 and 22 weeks of gestation.
An alternative screening method that can be done earlier in the pregnancy is the use of maternal blood markers to assess the risk of defects (sometimes called “AFP” or “quad testing”). When combined with a special ultrasound called a Nuchal Translucency measurement, this type of testing can give information about Down and Edward’s syndromes as early as 11-14 weeks. Without this special ultrasound, the testing is done at 15-20 weeks. It is important to understand that this testing, similar to ultrasound, does not provide a definitive diagnosis.
For an earlier, definitive diagnosis, a procedure called Chorionic Villus Sampling (CVS) can be done between 8 and 12 weeks. More technically difficult, it carries a slightly higher risk of miscarriage than amniocentesis, but the results are available much earlier.
To schedule your ”amnio” or any other prenatal testing call Health Care for Women in Salinas, California, or for any other questions or concerns you may have concerning gynecology, obstetrics, healthy pregnancies or general women’s healthcare, please call 831-758-8223, or visit the Health Care for Women website and get in contact today.