Amniocentesis
Encyclopedia
Amniocentesis is a medical procedure used in prenatal diagnosis
of chromosomal abnormalities and fetal infections, in which a small amount of amniotic fluid, which contains fetal tissues, is sampled
from the amnion
or amniotic sac surrounding a developing fetus
, and the fetal DNA is examined for genetic abnormalities. Using this process the sex of a child can also be determined and hence this procedure has some legal restrictions in some gender
biased countries.
(trisomy 21), Edwards syndrome
(trisomy 18), and Turner syndrome
(monosomy X). In regard to the fetus, the puncture heals and the amniotic sac replenishes the liquid over the next 24–48 hours.
Later on, it also can be used to detect problems such as:
An emerging indication for amniocentesis is in the management of preterm rupture of membranes where measurement of certain amniotic fluid inflammatory markers may be helpful. If amniotic fluid IL-6, a marker of inflammation, is elevated, the fetus is at high risk and delivery should be considered.
Serious complications can result in miscarriage. Other possible complications include preterm labor and delivery, respiratory distress, postural deformities, fetal trauma and alloimmunisation of the mother (rhesus disease). Studies from the 1970s originally estimated the risk of amniocentesis-related miscarriage at around 1 in 200 (0.5%). A more recent study (2006) has indicated this may actually be much lower, perhaps as low as 1 in 1,600 (0.06%). In contrast, the risk of miscarriage from chorionic villus sampling
(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.
Amniotic fluid embolism
has been described as a possible risk.
, and endothelial stem cell
s.
A potential benefit of using amniotic stem cells
over those obtained from embryos is that they side-step ethical concerns
among pro-life
activists by obtaining pluripotent lines of undifferentiated cells without harm to a fetus or destruction of an embryo. These stem cells would also, if used to treat the same individual they came from, sidestep the donor/recipient issue which has so far stymied all attempts to use donor-derived stem cells in therapies.
Artificial heart valves, working tracheas, as well as muscle, fat, bone, heart, neural and liver cells have all been engineered through use of amniotic stem cells
. Tissues obtained from amniotic cell lines show promise for patients suffering from congenital diseases/malformations of the heart, liver, lungs, kidneys, and cerebral tissue.
The first amniotic stem cells bank in US is active in Boston, Massachusetts.
Prenatal diagnosis
Prenatal diagnosis or prenatal screening is testing for diseases or conditions in a fetus or embryo before it is born. The aim is to detect birth defects such as neural tube defects, Down syndrome, chromosome abnormalities, genetic diseases and other conditions, such as spina bifida, cleft palate,...
of chromosomal abnormalities and fetal infections, in which a small amount of amniotic fluid, which contains fetal tissues, is sampled
Sampling (medicine)
In medicine, sampling is gathering of matter from the body to aid in the process of a medical diagnosis and/or evaluation of an indication for treatment, further medical tests or other procedures...
from the amnion
Amnion
The amnion is a membrane building the amniotic sac that surrounds and protects an embryo. It is developed in reptiles, birds, and mammals, which are hence called “Amniota”; but not in amphibians and fish , which are consequently termed “Anamniota”. The primary role of this is the protection of the...
or amniotic sac surrounding a developing fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
, and the fetal DNA is examined for genetic abnormalities. Using this process the sex of a child can also be determined and hence this procedure has some legal restrictions in some gender
Gender
Gender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...
biased countries.
Procedure
Before the start of the procedure, a local anesthetic can be given to the mother in order to relieve the pain felt during the insertion of the needle used to withdraw the fluid. After the local is in effect, a needle is usually inserted through the mother's abdominal wall, then through the wall of the uterus, and finally into the amniotic sac. With the aid of ultrasound-guidance, a physician punctures the sac in an area away from the fetus and extracts approximately 20 ml of amniotic fluid. After the amniotic fluid is extracted, the fetal cells are separated from the sample. The cells are grown in a culture medium, then fixed and stained. Under a microscope the chromosomes are examined for abnormalities. The most common abnormalities detected are Down syndromeDown syndrome
Down syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...
(trisomy 21), Edwards syndrome
Edwards syndrome
Trisomy 18 is a genetic disorder caused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960...
(trisomy 18), and Turner syndrome
Turner syndrome
Turner syndrome or Ullrich-Turner syndrome encompasses several conditions in human females, of which monosomy X is most common. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent...
(monosomy X). In regard to the fetus, the puncture heals and the amniotic sac replenishes the liquid over the next 24–48 hours.
Indications and results
Early in pregnancy, used for diagnosis of chromosomal and other fetal problems such as:- Down syndromeDown syndromeDown syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...
(trisomy 21) - Trisomy 13
- Trisomy 18
- Fragile X
- Rare, inherited metabolic disorders
- Neural tube defects (anencephalyAnencephalyAnencephaly is a cephalic disorder that results from a neural tube defect that occurs when the cephalic end of the neural tube fails to close, usually between the 23rd and 26th day of pregnancy, resulting in the absence of a major portion of the brain, skull, and scalp...
and spina bifidaSpina bifidaSpina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...
) by alpha-fetoproteinAlpha-fetoproteinAlpha-fetoprotein is a protein that in humans is encoded by the AFP gene....
levels.
Later on, it also can be used to detect problems such as:
- Infection
- Rh incompatibility
- Prediction of lung maturity
- Decompression of polyhydramnios
An emerging indication for amniocentesis is in the management of preterm rupture of membranes where measurement of certain amniotic fluid inflammatory markers may be helpful. If amniotic fluid IL-6, a marker of inflammation, is elevated, the fetus is at high risk and delivery should be considered.
Risks and drawbacks
Amniocentesis is performed between the 15th–20th week of pregnancy; performing this test early can lead to injury to the baby's limbs. Most people do the test during the 18th week of pregnancy. The term "early amniocentesis" is sometimes used to describe use of the process between weeks 11 and 13.Serious complications can result in miscarriage. Other possible complications include preterm labor and delivery, respiratory distress, postural deformities, fetal trauma and alloimmunisation of the mother (rhesus disease). Studies from the 1970s originally estimated the risk of amniocentesis-related miscarriage at around 1 in 200 (0.5%). A more recent study (2006) has indicated this may actually be much lower, perhaps as low as 1 in 1,600 (0.06%). In contrast, the risk of miscarriage from chorionic villus sampling
Chorionic villus sampling
Chorionic villus sampling , sometimes misspelled "chorionic villous sampling", is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it...
(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.
Amniotic fluid embolism
Amniotic fluid embolism
Amniotic fluid embolism is a rare and incompletely understood obstetric emergency in which amniotic fluid, fetal cells, hair, or other debris enters the mother's blood stream via the placental bed of the uterus and triggers an allergic reaction. This reaction then results in cardiorespiratory ...
has been described as a possible risk.
Amniocentesis and stem cells
Recent studies have discovered that amniotic fluid can be a rich source of multipotent mesenchymal, hematopoietic, neural, epithelialAmniotic epithelial cells
Amniotic epithelial cells are a form of stem cells extracted from the placenta, and may become useful in fighting diseases and disorders of the nervous system. Artificial heart valves and working tracheas, as well as muscle, fat, bone, heart, neural and liver cells have all been engineered using...
, and endothelial stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
s.
A potential benefit of using amniotic stem cells
Amniotic stem cells
Amniotic stem cells are multipotent stem cells of mesenchymal origin extracted from amniotic fluid.Amniotic stem cells are able to differentiate into various tissue type such as skin, cartilage, cardiac tissue, nerves, muscle, and bone, and may have potential future medical applications.All over...
over those obtained from embryos is that they side-step ethical concerns
Stem cell controversy
The stem cell controversy is the ethical debate primarily concerning the creation, treatment, and destruction of human embryos incident to research involving embryonic stem cells. Not all stem cell research involves the creation, use, or destruction of human embryos...
among pro-life
Pro-life
Opposition to the legalization of abortion is centered around the pro-life, or anti-abortion, movement, a social and political movement opposing elective abortion on moral grounds and supporting its legal prohibition or restriction...
activists by obtaining pluripotent lines of undifferentiated cells without harm to a fetus or destruction of an embryo. These stem cells would also, if used to treat the same individual they came from, sidestep the donor/recipient issue which has so far stymied all attempts to use donor-derived stem cells in therapies.
Artificial heart valves, working tracheas, as well as muscle, fat, bone, heart, neural and liver cells have all been engineered through use of amniotic stem cells
Amniotic stem cells
Amniotic stem cells are multipotent stem cells of mesenchymal origin extracted from amniotic fluid.Amniotic stem cells are able to differentiate into various tissue type such as skin, cartilage, cardiac tissue, nerves, muscle, and bone, and may have potential future medical applications.All over...
. Tissues obtained from amniotic cell lines show promise for patients suffering from congenital diseases/malformations of the heart, liver, lungs, kidneys, and cerebral tissue.
The first amniotic stem cells bank in US is active in Boston, Massachusetts.
See also
- Chorionic villus samplingChorionic villus samplingChorionic villus sampling , sometimes misspelled "chorionic villous sampling", is a form of prenatal diagnosis to determine chromosomal or genetic disorders in the fetus. It entails sampling of the chorionic villus and testing it...
- Percutaneous umbilical cord blood samplingPercutaneous umbilical cord blood samplingPercutaneous umbilical cord blood sampling , also called cordocentesis, is a diagnostic genetic test that examines blood from the fetal umbilical cord to detect fetal abnormalities. PUBS provides a means of rapid chromosome analysis and is useful when information cannot be obtained through...
- Prenatal diagnosisPrenatal diagnosisPrenatal diagnosis or prenatal screening is testing for diseases or conditions in a fetus or embryo before it is born. The aim is to detect birth defects such as neural tube defects, Down syndrome, chromosome abnormalities, genetic diseases and other conditions, such as spina bifida, cleft palate,...
- Amniotic stem cellsAmniotic stem cellsAmniotic stem cells are multipotent stem cells of mesenchymal origin extracted from amniotic fluid.Amniotic stem cells are able to differentiate into various tissue type such as skin, cartilage, cardiac tissue, nerves, muscle, and bone, and may have potential future medical applications.All over...
- Amniotic fluidAmniotic fluidAmniotic fluid or liquor amnii is the nourishing and protecting liquid contained by the amniotic sac of a pregnant woman.- Development of amniotic fluid :...
External links
- Amniodex is an interactive decision support intervention designed for women faced with the decision of whether to undergo amniocentesis.
- The Amniocentesis Report A Decision Guide for Expectant Parents and Health Care Professionals.
- http://www.sutherlandhealth.com/companies/condomania/product-range/vision/amniotic-leak-detector