Amniocentesis (also referred to as amniotic fluid test or AFT), is a medical procedure used in prenatal diagnosis of genetic abnormalities and fetal infections, in which a small amount of amniotic fluid, which contains fetal tissues, is extracted from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for genetic abnormalities. Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Prenatal testing is Testing for diseases or conditions in a Fetus or Embryo before it is born For the alien race in Stephen Donaldson 's The Gap Cycle, see Amnion (Gap Cycle. A fetus (or foetus or fœtus) is a developing Mammal or other Viviparous Vertebrate, after the Embryonic stage and
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Procedure
Before the actual procedure, a local anesthetic is sometimes given to relieve the pain when inserting the needle used to withdraw the fluid. A needle is usually inserted through the mother's abdominal wall or at the end of the vagina, and through the wall of the uterus into the amniotic sac. The vagina (from Latin, literally " Sheath " or " Scabbard " is a fibromuscular tubular tract leading from the Uterus With assistance from ultrasound, a physician aims towards an area of the sac that is away from the fetus and extracts a small amount of amniotic fluid for testing. Not to be confused with Supersonic. Ultrasound is cyclic Sound pressure with a Frequency greater than the upper The puncture heals, and the amniotic sac replenishes the liquid over a day or so. After the amniotic fluid is extracted, the fetal cells are separated from it using a centrifuge, and the fetal chromosomes are examined for abnormalities. A centrifuge is a piece of equipment generally driven by a motor that puts an object in Rotation around a fixed axis, applying a force perpendicular to the axis A chromosome is an organized structure of DNA and Protein that is found in cells. Various genetic testing may be performed, but the three most common abnormalities tested for are Down's syndrome, Trisomy 18 and spina bifida. Genetic testing allows the genetic Diagnosis of vulnerabilities to inherited Diseases, and can also be used to determine a person's Ancestry. Down syndrome, Down's syndrome, or trisomy 21 is a Chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. Trisomy 18 or Edwards Syndrome is a Genetic disorder caused by the presence of all or part of an extra 18th chromosome. Spina bifida ( Latin: "split spine" is a developmental Birth defect involving the Neural tube: incomplete closure of the Embryonic neural Amniocentesis can be performed as soon as sufficient amniotic fluid surrounds the fetus to allow a sample to be recovered relatively safely, usually no earlier than the 14th week of pregnancy. Often, genetic counseling is offered in conjunction with amniocentesis. Genetic counseling is the process by which patients or relatives at risk of an inherited disorder are advised of the consequences and nature of the disorder the probability of developing
In addition to the fetal cells, some tests may examine the amniotic fluid for indications of non-genetic diseases the fetus might have. Levels of chemical substances (such as alpha-fetoprotein) can be measured to detect other health problems such as hydrocephalus. Alpha-fetoprotein ( AFP) is a molecule produced in the developing Embryo Hydrocephalus (pronunciation ˌhaɪˌdɹoʊˈsɛfələs is a term derived from the Greek words "hydro" meaning water and "cephalus" meaning head and this condition
An alternative test to examine the genome of the developing fetus is chorionic villus sampling, or CVS. Chorionic villus sampling (CVS is a form of Prenatal diagnosis to determine chromosomal or Genetic disorders in the Fetus.
A side benefit of genetic analysis through amniocentesis or CVS is that the sex of the fetus may be determined with 100% accuracy.
Risks
Although the procedure is routine, possible complications include infection of the amniotic sac from the needle, and failure of the puncture to heal properly, which can result in leakage or infection. Serious complications can result in miscarriage. Other possible complications include preterm labor and delivery, respiratory distress, postural deformities, fetal trauma and alloimmunisation (rhesus disease). Rh disease (also known as Rh (D disease, Rhesus disease, RhD Hemolytic Disease of the Newborn, Rhesus D Hemolytic Disease of the Newborn or The risk of amniocentesis-related miscarriage is generally thought to be 1 in 200,[1] although a recent study has indicated this may actually be much lower, perhaps 1 in 1,600. [2] In contrast, the risk of miscarriage for CVS is believed to be approximately 1 in 100, although CVS may be done up to four weeks earlier, and may be preferable if the possibility of genetic defects is thought to be higher [3].
See also
References
Dictionary
amniocentesis
-noun
- A procedure for obtaining amniotic fluid from a pregnant animal, by inserting a hollow needle through the abdominal wall and into the amniotic sac. Used in diagnosing possible genetic defects and/or obstetric complications.
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