Tag Archives: Amniotic fluid

Chorionic Villus Sampling

Definition
Chorionic villi are small structures in the placenta that act like blood vessels. These structures contain cells from the developing fetus. A test that removes a sample of these cells through a needle is called chorionic villus sampling (CVS).Chorionic villus sampling (CVS) is the removal of a small piece of placenta tissue (chorionic villi) from the uterus during early pregnancy to screen the baby for genetic defects
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CVS answers many of the same questions as amniocentesis about diseases that the baby might have. Diseases that can be diagnosed with CVS include Tay-Sachs, sickle cell anemia, cystic fibrosis, thalassemia, and Down syndrome. (Rh incompatibility and neural tube defects, however, can be diagnosed only through amniocentesis.) CVS can be done earlier in pregnancy than amniocentesis and can be done when there is not enough amniotic fluid to allow amniocentesis. However, it has some extra risks when compared with amniocentesis.

Why the Test is Performed
The test is a way of detecting genetic disorders. The sample is used to study the DNA, chromosomes, and enzymes of the fetus. It can be done sooner than amniocentesis, about 10 to 12 weeks after your last menstrual period. Test results take about 1 to 2 weeks, whereas amniocentesis results may take longer.

Chorionic villus sampling does not detect neural tube defects. If neural tube defects or Rh incompatibility are a concern, an amniocentesis will be performed.

This test can usually not diagnose problems in the way the body forms.

How the Test is Performed
CVS can be done through the cervix (transcervical) or through the abdomen (transabdominal). The techniques are equally safe when done by a provider with experience, although miscarriage rates are slightly higher when done through the cervix. The health care provider will use ultrasound to pick the safest approach and as a guide during sampling.

An abdominal ultrasound is performed to determine the position of the uterus, the size of the gestational sac, and the position of the placenta within the uterus. Your vulva, vagina, cervix, and abdomen are cleaned with an antiseptic such as Betadine.

The transcervical procedure is performed by inserting a thin plastic tube through the vagina and cervix to reach the placenta. The provider uses ultrasound images to help guide the tube into the appropriate area and then removes a small sample of chorionic villus tissue.

The transabdominal procedure is performed by inserting a needle through the abdomen and uterus and into the placenta. Ultrasound is used to help guide the needle, and a small amount of tissue is drawn into the syringe.

The sample is placed in a dish and evaluated in a laboratory.

What happens when the test is performed.
There are two ways that your doctor can perform CVS. Some patients have the sampling done through the vagina and cervix. Most patients have the sampling done through the abdominal wall. For both types of sampling, you lie on your back on an examination table and the doctor uses ultrasound to locate the fetus and the placenta.

If the sampling is to be done through the vagina and cervix, you place your feet in footrests and bend your knees up, as you would for a pelvic examination. A speculum (a device that looks like a duck-bill that can be opened and closed) is used to open the vagina so that your doctor can see inside. A long tube, much narrower than a straw, is inserted through the cervix and moved forward while your doctor watches on the ultrasound until it is next to the fetal side of the placenta. A small sample of the lining around the fetus is then pulled into the tube for testing.

If the sampling is to be done through the abdominal wall, your lower abdomen is cleaned with an antibacterial soap. In some cases, the doctor uses a small needle to inject a numbing medicine just under the skin, so that you do not feel the sampling needle. (Because the sampling needle does not cause much more stinging than the numbing medicine itself, not every doctor includes this step.) A hollow needle several inches long is inserted through the skin and muscle of the abdomen and through the wall of the uterus, to the edge of the placenta. This needle is held in place as a guide needle. A narrower needle is then inserted through the first needle and is rotated and moved inward and outward a number of times while a sample is collected into an attached syringe.

The fetal heart tones and the mother’s blood pressure and heart rate are checked at the beginning and end of the procedure. The whole procedure takes close to 30 minutes.

How to Prepare for the Test.
CVS can be done between the 10th and 13th weeks of pregnancy. Tell your doctor ahead of time if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist’s office.

Your health care provider will explain the procedure, its risks, and alternative procedures such as amniocentesis. Genetic counseling is recommended prior to the procedure. This will allow you to make an unhurried, informed decision regarding options for prenatal diagnosis.

You will be asked to sign a consent form before this procedure, and you may be asked to wear a hospital gown.

The morning of the procedure you may be asked to drink fluids and refrain from urinating to fill your bladder, which allows adequate visualization so the sample may be taken.

How the Test Will Feel
The ultrasound doesn’t hurt. A clear, water-based conducting gel is applied to the skin to help with the transmission of the sound waves. A handheld probe called a transducer is then moved over the area. In addition, your health care provider may apply pressure on your abdomen to find the position of your uterus.

The antiseptic cleansing solution will feel cold at first nd may irritate your skin if not washed off after the procedure. Some people are allergic to Betadine. Notify your health care provider if you are allergic to Betadine or if you have any other allergies.

Some women say the vaginal approach feels like a Pap smear with some discomfort and a feeling of pressure. There may be a small amount of vaginal bleeding following the procedure.

An obstetrician can perform this procedure in about 5 minutes, after the preparation

Risk Factors:

The risks of CVS are only slightly higher than those of an amniocentesis.

Possible complications include:

* Bleeding
* Infection
* Miscarriage
* Rh incompatibility in the mother
* Rupture of membranes

Signs of complications include:

* Excessive bleeding
* Excessive vaginal discharge
* Fever

The risk of miscarriage and other complications from CVS is slightly higher than the risk from amniocentesis, although some parents feel that it is worth the extra risk to be able to makedecisions earlier in the pregnancy if the results show the baby has a health problem. There have also been some reports that suggest there is a very small risk of birth defects (abnormal limbs) in the fetus.

One particular difficulty with this test is that due to variability in the cells of the placenta (called mosaicism), occasionally you can have an abnormal test result even if the baby is normal and healthy. This might lead you to make decisions about pregnancy termination that you would not have made if you had better information.

Some women have vaginal bleeding after the procedure. Infection is uncommon.

Report any signs of complications to your health care provider.

CVS may also cause limb problems in the fetus. This risk appears to be very low (1 in 3,000) when CVS is performed after 10 weeks gestational ag

Time to know the  result of the test
Chromosome analysis of the sample takes two weeks or more. The results of some tests may be available sooner.

RESULTS:-

Normal Results
A normal result means there are no signs of any genetic defects. However the test could miss some genetic defects.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

An abnormal result may be a sign of more than 200 disorders, including:

* Down syndrome
* Hemoglobinopathies
* Tay-Sachs disease

Considerations
If your blood is Rh negative, you may receive RhoGAM to prevent Rh incompatibility.
You will receive a follow-up ultrasound 2 to 4 days after the procedure to make sure the pregnancy is proceeding normally.

Resources:
https://www.health.harvard.edu/fhg/diagnostics/chorionic-villus-sampling.shtml
http://www.nlm.nih.gov/medlineplus/ency/article/003406.htm

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Amniocentesis

Definition:
Amniocentesis (also referred to as amniotic fluid test or AFT), 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 extracted from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for genetic abnormalities
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 show whether the lungs of the baby are mature enough to allow it to survive if it were elivered right away.

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Amniocentesis is often recommended for pregnant women over age 35, women who have an abnormal “triple screen” blood test during pregnancy, or women who have (or whose husbands have) a family history of certain diseases or birth defects.

How do you prepare for the test?

You should have a serious discussion with your obstetrician regarding whether to have amniocentesis. Amniocentesis may be done anytime between the 14th and 20th weeks of pregnancy to test for fetal abnormalities. To check on fetal lung development, the test may be done late in the third trimester.

Tell your doctor ahead of time if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist’s office.

Just before the test, you should empty your bladder.

How the test is performed ?
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 through the wall of the uterus into the amniotic sac. With the aid of ultrasound-guidance, a physician aims towards an area of the sac that is away from the fetus and extracts approximately 20ml of amniotic fluid for testing. 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. 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 syndrome, Edward syndrome [Trisomy 18] and Turner syndrome [Monosomy X]. Amniocentesis is most safely performed after the 14th-16th week of pregnancy, does not need to be done before then due to risk it can to to the babys limbs. Usually genetic counseling is offered prior to amniocentesis.

What happens when the test is performed?
You wear a hospital gown and lie on your back on a table. An ultrasound is done to show the location of the fetus and placenta. Your lower abdomen is cleaned with an antibacterial soap. In some cases, the doctor uses a small needle to inject a numbing medicine just under the skin, so you do not feel the amniocentesis sampling needle later. (Because the sampling needle does not cause much more stinging than the numbing medicine itself, not every doctor includes this step.)

The hollow sampling needle is several inches long and is inserted through the skin and abdominal muscle and then through the wall of the uterus. A syringe attached to the needle is used to collect a sample of fluid.

The baby’s heart tones and the mother’s blood pressure and heart rate are checked at the beginning and end of the procedure. The whole procedure takes close to 30 minutes.

Risk Factors:
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). 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

Most women experience a few hours of mild pelvic cramping, and a few will have slight vaginal bleeding. About 1 in 100 women will have a temporary leak of amniotic fluid through the vagina; this usually causes no problem.

There is a small risk of miscarriage associated with amniocentesis; this occurs in about 1 in every 200 to 400 cases, depending in part on the timing of the test and the experience level of the physician performing it. Other risks (such as infection or injury to the fetus that does not cause miscarriage) are extremely rare.

What must you do after the test is over?
If the test confirms that you are Rh incompatible with the fetus, you will need to receive an injection of a medicine called Rh immune globulin (Rhogam) to protect the baby from complications.

Let your doctor know immediately if you are having any vaginal bleeding, fluid leakage, or strong abdominal pain.

Time to know the result:
Chromosome analysis of the fluid sample takes two weeks or more. The results of some tests may be available sooner.

Amniocentesis and stem cells:
Recent studies discovered that in amniotic fluid there are a lot of multipotent stem cell, mesenchymal, hematopoietic, neural,epithelial and endothelial stem cell[1][2][3]. Amniotic stem cells don’t have ethical problem. In fact, in harvesting embryonic stem cells, a human embryo is destroyed, and so it’s considered it immoral. Another 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.

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 [4]. Tissues obtained from amniotic cell lines show enormous promise for patients suffering from congenital diseases/malformations of the heart, liver, lungs, kidneys, and cerebral tissue

You may click to see:->HOW TO – Isolate amniotic stem cells from a placenta, at home

Resources:
https://www.health.harvard.edu/fhg/diagnostics/amniosentesis.shtml
http://en.wikipedia.org/wiki/Amniocentesis

http://healthlibrary.epnet.com/GetContent.aspx?token=7e9094f4-c284-4b3a-8f7c-867fd12b36ee&chunkiid=14762

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Infections May Cause Premature Births

Undiagnosed infections may be causing a significant number of premature births, researchers reported on Monday after finding bacteria or fungi in 15 per cent of the amniotic fluid samples taken from women in pre-term labor.

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The heavier the infection, the more likely the women were to deliver younger, sicker infants, the team at Stanford University in California found.

“If we could prevent these infections in the first place, or detect them sooner, we might one day be able to prevent some of these premature births,” Dr. Dan DiGiulio, who worked on the study, said in a statement.

More and more children are being born prematurely in the United States, with 12 per cent percent of births coming before the 37th week of gestation. Premature babies are vulnerable to breathing problems, underdeveloped organs, infections and cerebral palsy.

DiGiulio’s team looked for the DNA of germs in amniotic fluid samples collected from 166 women in pre-term labor at the Detroit Medical Center between October 1998 and December 2002. They used this method and standard laboratory cultures to determine that 25 of the 166 samples were infected with either bacteria or fungi. They also found at least one unknown organism that could be a new species.

All 25 of the women with infected amniotic fluid went on to deliver their babies pre-term, while 53 of the women with no infections were able to stop their labor. Now the team is working to see if infections can be detected before pre-term labor starts, which could lead to new prevention or treatment approaches.

Sources: The Times Of India

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