Amniocentesis: A procedure in which amniotic fluid and cells are taken from the uterus for testing. The procedure uses a needle to withdraw fluid and cells from the sac that holds the fetus. Show
Aneuploidy: Having an abnormal number of chromosomes. Types include trisomy, in which there is an extra chromosome, or monosomy, in which a chromosome is missing. Aneuploidy can affect any chromosome, including the sex chromosomes. Down syndrome (trisomy 21) is a common aneuploidy. Others are Patau syndrome (trisomy 13) and Edwards syndrome (trisomy 18). Carrier Screening: A test done on a person without signs or symptoms to find out whether he or she carries a gene for a genetic disorder. Cell-Free DNA: DNA from the placenta that moves freely in a pregnant woman’s blood. Analysis of this DNA can be done as a noninvasive prenatal screening test. Cells: The smallest units of a structure in the body. Cells are the building blocks for all parts of the body. Chorionic Villus Sampling (CVS): A procedure in which a small sample of cells is taken from the placenta and tested. Chromosomes: Structures that are located inside each cell in the body. They contain the genes that determine a person’s physical makeup. Cystic Fibrosis (CF): An inherited disorder that causes problems with breathing and digestion. Diagnostic Tests: Tests that look for a disease or cause of a disease. DNA: The genetic material that is passed down from parent to child. DNA is packaged in structures called chromosomes. Down Syndrome (Trisomy 21): A genetic disorder that causes abnormal features of the face and body, medical problems such as heart defects, and mental disability. Most cases of Down syndrome are caused by an extra chromosome 21 (trisomy 21). Edwards Syndrome (Trisomy 18): A genetic condition that causes serious problems. It causes a small head, heart defects, and deafness. Fetus: The stage of human development beyond 8 completed weeks after fertilization. Genes: Segments of DNA that contain instructions for the development of a person’s physical traits and control of the processes in the body. The gene is the basic unit of heredity and can be passed from parent to child. Genetic Counselor: A health care professional with special training in genetics who can provide expert advice about genetic disorders and prenatal testing. Genetic Disorders: Disorders caused by a change in genes or chromosomes. Inherited Disorders: Disorders caused by a change in a gene that can be passed from parents to children. Monosomy: A condition in which there is a missing chromosome. Mutations: Changes in genes that can be passed from parent to child. Neural Tube Defects (NTDs): Birth defects that result from a problem in development of the brain, spinal cord, or their coverings. Nuchal Translucency Screening: A test to screen for certain birth defects, such as Down syndrome, Edwards syndrome, or heart defects. The screening uses ultrasound to measure fluid at the back of the fetus’s neck. Obstetrician: A doctor who cares for women during pregnancy and their labor. Patau Syndrome (Trisomy 13): A genetic condition that causes serious problems. It involves the heart and brain, cleft lip and palate, and extra fingers and toes. Placenta: An organ that provides nutrients to and takes waste away from the fetus. Screening Tests: Tests that look for possible signs of disease in people who do not have signs or symptoms. Sex Chromosomes: The chromosomes that determine a person’s sex. In humans, there are two sex chromosomes, X and Y. Females have two X chromosomes and males have an X and a Y chromosome. Sickle Cell Disease: An inherited disorder in which red blood cells have a crescent shape, which causes chronic anemia and episodes of pain. Tay–Sachs Disease: An inherited disorder that causes mental disability, blindness, seizures, and death, usually by age 5. Trimester: A 3-month time in pregnancy. It can be first, second, or third. Trisomy: A condition in which there is an extra chromosome. Ultrasound Exams: Tests in which sound waves are used to examine inner parts of the body. During pregnancy, ultrasound can be used to check the fetus. Amniocentesis is a test done during pregnancy. During amniocentesis, an ultrasound wand (transducer) is used to show a baby's position in the uterus on a monitor. A sample of amniotic fluid, which contains fetal cells and chemicals produced by the baby, is then taken for testing. Amniocentesis is done to remove amniotic fluid and cells from the uterus for testing or treatment. Amniotic fluid surrounds and protects a baby during pregnancy. Amniocentesis can provide useful information about a baby's health. But it's important to know the risks of amniocentesis — and be prepared for the results. Products & Services
Why it's doneAmniocentesis can be done for a number of reasons:
Genetic amniocentesisGenetic amniocentesis can provide information about the baby's genes. Generally, genetic amniocentesis is offered when the test results might affect how to manage the pregnancy. Genetic amniocentesis is usually done between weeks 14 and 20 of pregnancy. Amniocentesis done before week 14 of pregnancy might lead to more complications. Reasons to consider genetic amniocentesis include:
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Request an Appointment at Mayo Clinic RisksAmniocentesis carries risks, which occur in approximately 1 in 900 tests. They include:
Remember, genetic amniocentesis is usually offered to pregnant people for whom the test results might greatly affect how they manage the pregnancy. The decision to have genetic amniocentesis is yours. Your health care provider or genetic counselor can give you information to help you decide. How you prepareYour health care provider will explain the procedure and ask you to sign a consent form. Consider asking someone to accompany you to the appointment for emotional support or to drive you home afterward. What you can expectAmniocentesis is usually done in an outpatient obstetric center or a health care provider's office. During the procedureFirst, a health care provider will use ultrasound to pinpoint where the baby is in the uterus. You'll lie on your back on an exam table with your belly showing. Your health care provider will apply a gel to your belly 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. A numbing medication generally isn't used. Most people report only mild soreness during the procedure. Guided by ultrasound, your health care provider will insert a thin, hollow needle through your stomach wall and into the uterus. A small amount of amniotic fluid is drawn into a syringe. The needle is then removed. You need to lie still while the needle is put in and the amniotic fluid is taken out. You might feel a sting when the needle enters your skin. You might feel cramping when the needle enters your uterus. After the procedureAfter amniocentesis, your health care provider will continue using the ultrasound to monitor your baby's heart rate. You might have cramping or mild pelvic pain after an amniocentesis. You can return to your regular activities after the test. The sample of amniotic fluid will be looked at in a lab. Some results might be available within a few days. Other results might take several weeks. Contact your health care provider if you have:
ResultsYour health care provider or a genetic counselor will help you understand your amniocentesis results. For genetic amniocentesis, test results can rule out or diagnose some genetic conditions, such as Down syndrome. Amniocentesis can't identify all genetic conditions and birth defects. If amniocentesis suggests that your baby has a genetic or chromosomal condition that can't be treated, you might face hard decisions. Seek support from your health care team and your loved ones. By Mayo Clinic Staff Request an Appointment at Mayo Clinic Oct. 07, 2022 Share on: FacebookTwitter Show references
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AdvertisementMayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Which medical procedure can be used to identify chromosomal abnormalities in a fetus?Chorionic Villus Sampling (CVS)
CVS is a test where the doctor collects a tiny piece of the placenta, called chorionic villus, which is then tested to check for chromosomal or genetic disorders in the baby.
Which procedure is used in diagnosis of chromosomal abnormalities?Amniocentesis is the most common invasive prenatal procedure for the detection of fetal chromosomal abnormalities.
What is the best method to detect genetic abnormalities in fetus?Noninvasive prenatal testing (NIPT), sometimes called noninvasive prenatal screening (NIPS), is a method of determining the risk that the fetus will be born with certain genetic abnormalities. This testing analyzes small fragments of DNA that are circulating in a pregnant woman's blood.
What medical procedures are used to diagnose problems with the fetus?Chorionic villus sampling and amniocentesis are used to detect abnormalities in a fetus. During both procedures, ultrasonography is used for guidance. In chorionic villus sampling, a sample of chorionic villi (part of the placenta) is removed by one of two methods.
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