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Definition: Amniocentesis from Black's Medical Dictionary, 43rd Edition

A diagnostic procedure for detecting abnormalities of the FETUS. Usually carried out between the 16th and 18th week of pregnancy, amniocentesis is performed by piercing the amniotic sac in the pregnant UTERUS with a hollow needle, under ULTRASOUND guidance and withdrawing a sample of AMNIOTIC FLUID for laboratory analysis. As well as checking for the presence of abnormal fetal cells, the procedure can show the sex of the fetus. The risk of early rupture of the fetal membranes or of miscarriage is low (around 1 per cent). Currently it is offered (in the UK) to women over age 35, those who have previously had a baby with SPINA BIFIDA, CHROMOSOME abnormality and those known to carry a serious genetic disorder. It is also offered to women who have had an abnormal result on fetal ultrasound screening or blood testing for DOWN'S SYNDROME.


Amniocentesis

From Encyclopedia of Special Education: A Reference for the Education of Children, Adolescents, and Adults with Disabilities and Other Exceptional Individuals
Amniocentesis is the sampling of amniotic fluid surrounding a fetus. A physician anesthetizes a small area of the pregnant woman’s abdomen, inserts a small needle through the abdominal wall, and, with the aid of ultrasonography, enters the amniotic sac and removes 20 ml (approximately 1 oz) of fluid. It is performed most frequently between 15 and 18 weeks gestation to detect hereditary disease or congenital defects in the fetus. One disadvantage is that analysis of the fluid takes 2 to 4 weeks. Damage to the fetus also may occur, but the risk is small—.06% or 1 in 1600 ( Eddleman, Malone, & Sullivan ,; March of Dimes ,). Midtrimester amniocentesis plays an important role in genetic and other prenatal counseling by providing potential parents with reproductive options. It should be considered when the pregnant woman is over 35, or a family history of genetic or congenital disorders is apparent ( Kaback ,; March of Dimes ,). Cytogenetic analysis of fetal fluid leads to prevention of…
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Full text Article Amniocentesis

From New Harvard Guide to Women's Health, The
Amniocentesis
Amniocentesis is a prenatal screening procedure in which a small quantity of the amniotic fluid surrounding the fetus is removed from the uterus of a pregnant woman to allow the chromosomes of the fetus to be examined. The test is usually performed between 16 and 20 weeks of pregnancy in women…
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Full text Article Amniocentesis

From Brenner's Encyclopedia of Genetics
Amniocentesis
Abstract Amniocentesis involves sampling the fluid from the amniotic sac during pregnancy. It is the main method used for the prenatal diagnosis of fetal disorders, including chromosome aberrations, metabolic defects, and genetic mutations. Keywords Fetal diagnosis Maternal serum markers Neural tube…
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Full text Article Amniocentesis

From Gale Encyclopedia of Children's Health: Infancy Through Adolescence
To perform amniocentesis, a physician uses an...
Amniocentesis is a procedure used to diagnose fetal defects in the early second trimester of pregnancy. A sample of the amniotic fluid, or the liquid that surrounds a fetus in the womb, is collected through a pregnant woman's abdomen using a needle and syringe. Tests performed on fetal cells found…
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Full text Article Amniocentesis

From Gale Encyclopedia of Medicine
A doctor punctures abdominal wall of pregnant...
Amniocentesis is a procedure used to diagnose fetal defects early in the second trimester of a pregnancy. A sample of the amniotic fluid, which surrounds a fetus in the womb, is collected through a pregnant woman's abdomen using a needle and syringe. Tests performed on fetal cells found in the…
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Full text Article Amniocentesis

From Encyclopedia of Special Education: A Reference for the Education of Children, Adolescents, and Adults with Disabilities and Other Exceptional Individuals
Amniocentesis is the sampling of amniotic fluid surrounding a fetus. A physician anesthetizes a small area of the pregnant woman’s abdomen, inserts a small needle through the abdominal wall, and, with the aid of ultrasonography, enters the amniotic sac and removes 20 ml (approximately 1 oz) of…
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Full text Article Amniocentesis

From Gale Encyclopedia of Nursing and Allied Health
Amniocentesis. (Saturn Stills/Science Source)
Amniocentesis is an optional but reliable procedure offered to pregnant women to obtain information about a developing fetus in the second trimester of pregnancy. It is primarily offered to pregnant women who are at increased risk, based on their age, family history, or other factor, of having a…
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From Harvard Medical School Health Topics A-Z
What is the test? Amniocentesis involves using a needle to take a sample of amniotic fluid, the fluid that surrounds a developing fetus during pregnancy. Tests of fetal cells found in this fluid can reveal the presence of Down syndrome or other chromosome problems in the baby. Amniocentesis can also…
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Full text Article Amniocentesis

From The Oxford Encyclopedia of the History of American Science, Medicine, and Technology
Amniocentesis literally means “to prick the amnion.” As a medical procedure, it was first developed in the 1930s to ease polyhydramnios, too much amniotic fluid, a serious, but rare condition in pregnancy. A sharp, hollow needle is introduced through a pregnant woman's abdominal and uterine walls, …
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Full text Article amniocentesis

From The Columbia Encyclopedia
(ăm´´nēō´´sĕntē'sĭs), diagnostic procedure in which a sample of the amniotic fluid surrounding a fetus is removed from the uterus by means of a fine needle inserted through the abdomen of the pregnant woman (see pregnancy ). The procedure can be done in a hospital or in a doctor's office. Ultrasound…
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Full text Article amniocentesis

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Sampling the amniotic fluid surrounding a fetus in the womb for diagnostic purposes. It is used to detect Down's syndrome and other genetic abnormalities. The procedure carries a 1 in 200 risk of miscarriage. A needle is inserted into the mother's abdominal wall and, usually under ultrasound…
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