Prenatal diagnostic techniques



Prenatal diagnosis is the process of determining the condition of a fetus (name given to unborn young from the end of the eighth week of development through birth) before it is born. This type of diagnosis has become an important part of pregnancy care.

The earliest form of prenatal testing was very simple. The mother noted fetal activity in the womb, and the doctor manually felt the unborn child through the mother's abdomen. Eventually machines were developed for listening to the fetal heartbeat.

Amniocentesis

Prenatal diagnosis began to improve with the development of amnio-centesis in the 1950s. In the 1960s the ability to culture cells from amniotic fluid was developed. Beginning in 1968, cells from amniotic fluid could be analyzed for chromosome disorders like Down's syndrome. Today, amniocentesis permits the diagnosis of a wide range of disorders. Amniocentesis is normally recommended at fourteen to sixteen weeks of pregnancy. Test results are usually available to the patient in two to three weeks.

Ultrasound

Ultrasound scanning has become the most popular method of prenatal testing. Ultrasound uses sound waves to produce a picture of the developing fetus. It has no known harmful effect on the mother or the unborn child and requires no probing or biological samples to be taken.

In 1977 so-called "real-time" ultrasound equipment became commercially available. The real-time mode shows detailed images of the moving fetus as the movement occurs. Real-time ultrasound was quickly applied to invasive (entering the body) prenatal diagnostic techniques. With

As this woman's labor progresses, an electronic sensor is attached to her abdomen to monitor uterine contractions and the fetal heartbeat.
As this woman's labor progresses, an electronic sensor is attached to her abdomen to monitor uterine contractions and the fetal heartbeat.
these techniques, a needle is inserted into the womb to take samples. The samples might be of amniotic fluid, fetal blood, or chorionic villi. The needle can be visually guided by the real-time ultrasound. By being able to guide the placement of the needle, damage to the fetus is avoided.

Chorionic Villus Sampling (CVS)

Chorionic villus sampling is when samples of fetal tissue are retrieved from the fetus. The samples are then analyzed for chromosomal, biochemical, and DNA content. One method of obtaining the sample through the cervix was described by Jan Mohr (1921-) in 1968. This method was abandoned because of a high rate of complications.

In 1982 a British group at the University College Hospital of London developed a new technique. Transcervical CVS sampling (taking a sample through the cervix) guided by real-time ultrasound became a safe procedure. Transabdominal CVS sampling (taking a sample through the abdomen) was first reported in 1984 and is used in some cases to avoid vaginal infection. Ultrasound-guided CVS is now widely used. It can be performed much earlier in pregnancy than amniocentesis and results are available within a week.

Measuring Alpha-Fetoprotein (AFP)

Another prenatal diagnostic test now given to most pregnant women measures maternal serum alpha-fetoprotein (MSAFP) levels. This test samples the mother's blood for the amount of AFP. AFP is a protein produced by the fetal liver. As levels of AFP in the mother's blood mirror the levels in the fetus, testing has been rapidly expanded to include more women. In 1984 it was reported that low MSAFP levels were associated with Down's syndrome. With this information, the need for more detailed testing can be identified earlier during the pregnancy.

Fetal blood sampling has been done since 1972. The sample is used to diagnose a variety of hereditary blood disorders. This procedure was improved upon by Fernand Daffos and his team in 1982. The group developed a method of retrieving samples of blood from the umbilical cord. They used a needle guided by real-time ultrasound imaging. This procedure is called cordocentesis, or percutaneous umbilical blood sampling (PUBS).

DNA Analysis

DNA analysis for specific gene disorders was introduced to prenatal testing in 1976. DNA from a number of different sources is examined. These sources include fetal samples plus maternal and paternal blood samples. This allows the doctors to identify genetic problems that might be transmitted by either parent. Over 260 single gene defects can now be diagnosed through DNA analysis, and the list continually grows.

Other New Procedures

Prenatal diagnostic testing is rapidly expanding. Nuclear magnetic resonance imaging ( MRI ) and spectroscopy (NMR) are new tools. The tests reveal biochemical information about fetal soft-tissue and organ structure and function. Fetal tissue sampling is an experimental technique. It is used to detect very rare hereditary and fatal skin disorders. Another not-yet-perfected experimental procedure is cell sorting. In cell sorting, fetal cells are isolated from the maternal blood for analysis. Prenatal testing is even carried out on some embryos, eggs, and sperm before in-vitro implantation.

After Diagnosis

Prenatal diagnosis is now moving in the direction of prenatal treatment. The field of prenatal surgery is in its infancy. A few conditions identified prenatally can be treated in the womb successfully by medicating the mother. Respiratory distress syndrome is one of these conditions. It is a prime killer of prematurely born infants. Another condition is methylamalonic acidemia. This is a rare vitamin metabolism defect.



User Contributions:

Nkere
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Jun 7, 2008 @ 4:16 pm
I want to know how possible it is to know the genotype of the fetus as early as few days after conception.
kalpesh
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Aug 15, 2008 @ 8:08 am
I want to know how possible it is to know the genotype of the fetus as early as few days after conception without taking any help from doctor.
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Sep 19, 2010 @ 8:08 am
i want to knw if it is possible to determine the genotype of the fetus as early as conception,because i need to decide whether or not to continue with my relatnship, in order to avoid giving birth to a sickle cell child.
Fate
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Oct 8, 2010 @ 5:05 am
I want to know if it is possible to know the genotype of a foetus within few weeks of conception.
Analia
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Feb 21, 2011 @ 8:08 am
My daughter was born with a genetic disorder McCune Albright. I had amniocentesis. Why this didn't show? Or they just didn't tell me?
Tunde
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Jul 11, 2011 @ 4:04 am
Pls,i want to know if amniocentesis procedure(To determine the genotype of the fetus) is available in Nigeria,where & the cost. Thanks.
irabor
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Sep 4, 2011 @ 3:15 pm
Please i will like to know if it is possible to know the genotype of the fetus can be checked in Nigeria via amniocentesis and where. Please reply ASAP.
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Oct 12, 2011 @ 5:05 am
pls i want to knw if the genotype of the fetus can be checked within 3-4wks of pregnacy in nigeria and pls name the hospital. Thanks.
Austin
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Nov 20, 2011 @ 4:04 am
Please i want to know if the fetal genotype can be determined in any hospital or laboratory in Nigeria. If it is possible, please where?
Daniel taiwo
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Jan 9, 2012 @ 4:16 pm
Hi pls i wnt to know if Fetus genotype can be know within howmany weeks, and which hospital has dat in tech in nigeria
Ismail
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Jan 13, 2012 @ 4:16 pm
Pls i want to know which type of test is available in Nigeria and where to check the genotype of unborn baby. Thanks
amaka
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Feb 14, 2012 @ 11:23 pm
Hi,I want to know if a fetus genotype can be check in 7 to 8 weeks of a pregnancy and where it can be cheched in Nigeria
emiiii
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Mar 26, 2012 @ 6:06 am
Hi,I want to know if a fetus genotype can be check in 7 to 8 weeks of a pregnancy and where it can be checked in Nigeria
Joy
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Apr 11, 2012 @ 9:09 am
i want to knw if it is possible to determine the genotype of the fetus as early as conception,because i need to decide whether or not to continue with my relatnship, in order to avoid giving birth to a sickle cell child.

I want to know if a fetus genotype can be check in 7 to 8 weeks of a pregnancy and where it can be checked in Nigeria
olasunkanmi
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Jun 2, 2012 @ 4:16 pm
I want to know if it is possible to know the genotype of a foetus within few weeks of conception.
Hami
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Jun 16, 2012 @ 4:04 am
Please I want to know the procedures and effects of the determination of the genotype of an unborn.
Rohoboth
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Sep 25, 2012 @ 1:13 pm
Thanks for educating millions of people who visit this site. The information you provided here gives a ray of hope to many who hitherto thought there was no hope for them. However, you will do more good if you provide a list of hospitals where amniocentesis test can be conducted in Nigeria. Thank you.
Chinedu
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Oct 1, 2012 @ 1:01 am
Good day, please i want to know if there is any remedy of preventing SS during child birth when both parents are AS. And in a case where both are deeply in love to each other, is it advicable to marry with such genotype?
chijioke
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Oct 12, 2012 @ 8:08 am
Good day ,pls i want to know if there is any hospital in lagos where fetus genotype can be checked. If yes pls let me know. is very important to me. thanks
Omoigui emmanuel
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Oct 13, 2012 @ 2:02 am
Pls i need to kwn the apparatus,method and procedures for blood Genotyping.is part of my project pls help me.thanks
osaivbie
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Oct 13, 2012 @ 12:12 pm
Pls I want to know where in nigeria and the cost of CVS. Or where aminotic fluid can be tested
May
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Oct 17, 2012 @ 2:02 am
How do I know the genotype of my baby who is just a week old in the womb?
Vicky
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Nov 20, 2012 @ 1:01 am
I would like to know if its possible to check the genotype of å child in the mothers womb few days after conception
Lanre
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Jan 31, 2013 @ 4:16 pm
Pls, where can amniocentesis be done in Nigeria (South West Nigeria) and what is the cost. Thanks.
vivian_ajaero@yahoo.com
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Feb 14, 2013 @ 1:01 am
where do i check the genotype of my unborn child in nigeria
ade bowale
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Mar 28, 2013 @ 11:23 pm
Pls I want to know if its possible to determine a fetus genotype in pregnancy,if yes,at how many weeks and is it done in Nigeria?
Abbey
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Apr 24, 2013 @ 1:01 am
Where can amniocentesis be performed in South West Nigeria and the possible cost. Thanks.
ipheanyi
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May 10, 2013 @ 9:09 am
Please where can I check the genotype of an unborn child and how much does it cost?
Lovy
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May 23, 2013 @ 10:10 am
Pls I want 2 confirm where fetal genotype is done here in Nigeria,and hw much it cost and d Doctor's phone number,Tanks
Asaa
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May 24, 2013 @ 4:04 am
Please where can I have CVS done in Nigeria? I have done it twice before, in the US and in South Africa. I want to know where I can do it in Nigeria to cut cost and I have no time to travel now. Please provide good places. i tried Sickle cell Foundation and I had a bad experience. i walked out and did it in SA. They were not professional at all.

Thank you as I await your response.
ifeoma
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Sep 11, 2013 @ 1:01 am
I want to knw where the test can be done and the cost for it tnx
Tessy
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Oct 25, 2013 @ 9:09 am
Pls, which hospital in nigeria can check the genotype of an unborn baby & the amount. Its urgent
lanre
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Nov 26, 2013 @ 2:14 pm
Good, i want to know the earliest week of pregnancy to check a baby's genotype in the womb.
Amaka
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Apr 7, 2014 @ 6:06 am
Please where can i do genotype test for my unborn baby in South Africa ?
lanre
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May 15, 2014 @ 4:16 pm
Is it possible 2 determine d genotype of an unborn child & how early in pregnancy.
ogechi
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Sep 17, 2014 @ 2:02 am
What is the exact time to test a baby's genotype status
dauda
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Sep 26, 2014 @ 8:08 am
pls can you tell us where the genotype of unborn child/foetus could be determined, at what period of gestation and the success rate. thank
Caston
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Apr 13, 2015 @ 4:04 am
Thanks for the enlightment and beam of hope. Pls, can I get name of hospital and doctors number to contact in order to make enquiries on how to book an appointment with them. Thanks
bisi
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Jul 19, 2015 @ 2:02 am
Pls I need the no of the doctor to call for proper explanation

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