What is a karyotype test?A karyotype test looks at the size, shape, and number of your chromosomes. Chromosomes are the parts of your cells that contain your genes. Genes are parts of DNA passed down from your mother and father. They carry information that determines your unique traits, such as height and eye color. Show
People normally have 46 chromosomes, divided into 23 pairs, in each cell. One of each pair of chromosomes comes from your mother, and the other pair comes from your father. If you have more or fewer chromosomes than 46, or if there is anything unusual about the size or shape of your chromosomes, it can mean you have a genetic disease. A karyotype test is often used to help find genetic defects in a developing baby. Other names: genetic testing, chromosome testing, chromosome studies, cytogenetic analysis What is it used for?A karyotype test may be used to:
Why do I need a karyotype test?If you are pregnant, you may want to get a karyotype test for your unborn baby if you have certain risk factors. These include:
Your baby or young child may need a test if he or she has signs of a genetic disorder. There are many types of genetic disorders, each with different symptoms. You and your health care provider can talk about whether testing is recommended. If you are a woman, you may need a karyotype test if you've had trouble getting pregnant or have had several miscarriages. While one miscarriage is not uncommon, if you have had several, it may be due to a chromosomal problem. You may also need a karyotype test if you have symptoms of or have been diagnosed with leukemia, lymphoma, or myeloma, or a certain type of anemia. These disorders can cause chromosomal changes. Finding these changes can help your provider diagnose, monitor, and/or treat the disease. What happens during a karyotype test?For a karyotype test, your provider will need to take a sample of your cells. The most common ways to get a sample include:
For amniocentesis:
Amniocentesis is usually done between week 15 and 20 of pregnancy. For CVS:
CVS is usually done between week 10 and 13 of pregnancy. Bone Marrow Aspiration and Biopsy. If you are being tested for or treated for a certain type of cancer or blood disorder, your provider may need to take a sample of your bone marrow. For this test:
Will I need to do anything to prepare for the test?You don't need any special preparation for karyotype testing. Are there any risks to the test?There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. Amniocentesis and CVS tests are usually very safe procedures, but they do have a slight risk of causing a miscarriage. Talk to your health care provider about the risks and benefits of these tests. After a bone marrow aspiration and biopsy test, you may feel stiff or sore at the injection site. This usually goes away in a few days. Your health care provider may recommend or prescribe a pain reliever to help. What do the results mean?If your results were abnormal (not normal,) it means you or your child has more or fewer than 46 chromosomes, or there is something abnormal about the size, shape, or structure of one or more of your chromosomes. Abnormal chromosomes can cause a variety of health problems. The symptoms and severity depend on which chromosomes have been affected. Some disorders caused by chromosomal defects include:
If you were tested because you have a certain type of cancer or blood disorder, your results can show whether or not your condition is caused by a chromosomal defect. These results can help your health care provider make the best treatment plan for you. Learn more about laboratory tests, reference ranges, and understanding results. Is there anything else I need to know about a karyotype test?If you are thinking about getting tested or have received abnormal results on your karyotype test, it may help to speak to a genetic counselor. A genetic counselor is a specially trained professional in genetics and genetic testing. He or she can explain what your results mean, direct you to support services, and help you make informed decisions about your health or the health of your child. References
What prenatal technique can be used to examine the status of the fetus by taking samples of the cells?Chorionic villus sampling (CVS), or chorionic villus biopsy, is a prenatal test that involves taking a sample of tissue from the placenta to test for chromosomal abnormalities and certain other genetic problems.
What common technique can be used to confirm the presence of an embryo or fetus within the womb?A fetal ultrasound (sonogram) is an imaging technique that uses sound waves to produce images of a fetus in the uterus. Fetal ultrasound images can help your health care provider evaluate your baby's growth and development and monitor your pregnancy.
Which technique can be used at the earliest stage in a pregnancy to provide a sample for fetal genetic testing?Chorionic villus sampling can provide information about your baby's genetic makeup. Generally, chorionic villus sampling is offered when the test results might have a significant impact on the management of the pregnancy or your desire to continue the pregnancy.
What is the most common method used for fetal testing?Ultrasound. An ultrasound scan is a diagnostic technique that uses high-frequency sound waves to create an image of the internal organs. A screening ultrasound is sometimes done during the course of your pregnancy to check normal fetal growth and verify the due date.
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