Your health care provider or genetic counselor can help you weigh all the factors in the decision. If you're having amniocentesis done before week 20 of pregnancy, it might be helpful to have your bladder full during the procedure to support the uterus. Drink plenty of fluids before your appointment. After 20 weeks of pregnancy, your bladder should be empty during amniocentesis to minimize the chance of puncture. Your health care provider will explain the procedure and ask you to sign a consent form before the procedure begins.
Consider asking someone to accompany you to the appointment for emotional support or to drive you home afterward.
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 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 A small amount of amniotic fluid will be withdrawn into a syringe, and the needle will be removed.
The specific amount of amniotic fluid withdrawn depends on the number of weeks the pregnancy has progressed. You'll need to lie still while the needle is inserted and the amniotic fluid is withdrawn.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 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. Results can take anywhere from a few days to a couple of weeks to be returned. Amniocentesis is usually performed between 14 and 20 weeks. Some medical facilities may perform amniocentesis as early as 11 weeks.
Amniocentesis can be used later in the third trimester for a few reasons. Your healthcare provider may recommend the procedure if your membranes have ruptured prematurely, in order to assess for uterine infections.
Amniocentesis may also help determine the severity of fetal anemia in babies with Rh disease, and assist your physician to determine whether the fetus requires lifesaving blood transfusions. Amniocentesis is sometimes done to assess lung maturity.
If so, this is done shortly before delivery. Amniocentesis detects chromosome abnormalities, neural tube defects, and genetic disorders. Down syndrome or Trisomy 21 is the most common chromosome abnormality.
Genetic disorders include disorders such as cystic fibrosis. The most common neural tube defect is spina bifida. Amniocentesis also provides access to DNA for paternity testing prior to delivery.
DNA is collected from the potential father and is compared to DNA obtained from the baby during amniocentesis. Although the probabilities of identification are high, this test does not measure the severity of these birth defects. Alpha-fetoprotein levels and advanced level ultrasounds may assist in assessing the degree of disability that may be present.
Although amniocentesis is considered to be a safe procedure, it is recognized as an invasive diagnostic test that does pose potential risks. According to the Mayo Clinic, it is performed approximately , times a year.
Miscarriage is the primary risk related to amniocentesis. The risk of miscarriage ranges from 1 in to 1 in In facilities where amniocentesis is performed regularly, the rates are closer to 1 in Miscarriages can occur because of infection in the uterus, water breaking, or labor being induced prematurely.
You and your fetus will be monitored for a time after the procedure. Your vital signs and the fetal heart rate will be checked regularly for an hour or longer. The amniotic fluid sample will be sent to a genetics lab.
Alpha-fetoprotein, a protein made by the fetus and present in the fluid, may be measured to rule out an open neural tube defect, such as spina bifida.
Testing may also be done for other substances related to metabolic or genetic conditions. Depending on test results, counseling with a genetics specialist may be advised. You may feel some cramping during or after the procedure. If you feel lightheaded, dizzy, or nauseated, tell the nurse.
You may be told to rest on your left side. After the test, rest at home and avoid strenuous activities for at least 24 hours, or as directed by your healthcare provider. Your healthcare provider may give you other instructions after the procedure, depending on your situation. Health Home Treatments, Tests and Therapies. Amniotic fluid is a clear, pale yellow fluid that: Protects the fetus from injury Protects against infection Allows the baby to move and develop properly Helps control the temperature of the fetus Along with various enzymes, proteins, hormones, and other substances, the amniotic fluid contains cells shed by the fetus.
Why might I need an amniocentesis? Some conditions where an amniocentesis may be used for genetic and chromosome testing in the second trimester of pregnancy include: Family history or previous child with a genetic disease or metabolic disorder, such as Down syndrome, cystic fibrosis, or Tay Sachs disease Risk of open neural tube defects, such as spina bifida Maternal age over 35 years by the pregnancy due date Abnormal maternal screening tests Risk of a sex-linked genetic disease Amniocentesis may be used in the third trimester of pregnancy to check for: Fetal lung maturity when there is a potential for premature birth Uterine infection Rh disease Your healthcare provider may have other reasons to recommend an amniocentesis.
What are the risks of an amniocentesis? Certain factors or conditions may interfere with an amniocentesis. These factors include: Pregnancy earlier than 14 weeks The position of the baby, placenta, amount of fluid, or mother's anatomy Women with twins or other multiples will need fluid samples from each amniotic sac to study each baby You may have other risks, depending on your condition. How do I get ready for an amniocentesis? Your healthcare provider will explain the procedure and you can ask questions.
You will be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if anything is unclear. Generally, there are no special limits on diet or activity before an amniocentesis.
Tell your healthcare provider if you are sensitive to or are allergic to any medicines, latex, tape, or anesthesia. Tell your healthcare provider of all medicines prescription and over-the-counter , herbs, vitamins, and supplements that you are taking.
Tell your healthcare provider if you have a history of bleeding disorders or if you are taking any anticoagulant blood-thinning medicines, aspirin, or other medicines that affect blood clotting.
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