Amniocentesis is a procedure that can be done during the second trimester of pregnancy (usually between 15 and 22 weeks). Amniocentesis involves getting some of the fluid from around the baby so that the lab can test for chromosome and genetic conditions.

Because amniocentesis is an invasive procedure, there is a risk of less than 1 in 200 (or 0.5%) for complications that can lead to a miscarriage. That also means that more than 99.5% of women who have an amniocentesis will not have a procedure-related miscarriage.

There are many different types of testing that can be done on amniocentesis samples, including traditional chromosome analysis (karyotype), FISH, chromosomal microarray, and familial mutation testing. All of this testing is considered to be diagnostic testing for chromosome and genetic conditions, meaning it can typically provide a ‘yes’ or ‘no’ answer, as opposed to screening tests which only tell you the chances or odds.

Amniocentesis can screen for many things, but cannot screen for all medical conditions or birth defects.

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Related Articles

  • Chorionic villus sampling, or CVS, is a procedure that can be done during the first trimester of pregnancy (usually between 11 and 14 weeks). CVS involves getting some of the tissue from the placenta (the chorionic villi) so that the lab can test for chromosome and genetic conditions. Because CVS…
  • FISH, or fluorescence in situ hybridization, is a test that can be done on the cells from a chorionic villus sampling (CVS) or amniocentesis procedure. FISH can provide rapid results (usually within 48 to 72 hours) for limited chromosome conditions. Most labs offer FISH testing on CVS or amniocentesis cells…
  • A chromosome analysis, or karyotype, is the traditional testing that has been done on cells from chorionic villus sampling (CVS) and amniocentesis procedures. A karyotype involves the lab examining the cells and determining the number of chromosomes. How the lab determines the number of chromosomes is a lengthy and complicated…
  • Chromosomal microarray (CMA) is a type of chromosome test that can be done during pregnancy along with an amniocentesis or chorionic villus sampling (CVS), or can be done for patients who are suspected of having an underlying genetic syndrome. CMA can detect if there are small bits of missing (deletion)…

Last updated on Aug 21st, 2019

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