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What to Expect at Your PreNatal Exam

on April 9, 2010 10:33 AM | Permalink

When I get to my doctor's office, I always assume, they have done this before, I don't need to worry, I just need to follow their directions and advice. I barely think of questions, until I am out the door and well on my way home. Here are some tips to what will happen during your prenatal exams. this is an informational site only, not meant to replace your OB/GYNs directions or advice - just another spot on the internet to help you through this very exciting time in your life:

First trimester

The first ultrasound can verify that your budding baby is alive and well, give you his or her estimated gestational age and identify multiples. From the resulting images, your doctor takes nasal bone measurements and looks for nuchal translucency (fluid behind the neck) as an early sign of Down syndrome. The ultrasound image appears as a result of measured sound waves; there is no risk involved.

Blood tests (for the PAPPA protein and hCG hormone) may be conducted at the same time as the ultrasound. At this point, the blood is tested for Down syndrome (with 91 percent sensitivity and a 5 percent false positive rate) and trisomy 13 & 18--chromosome anomalies that are associated with severe mental retardation and early infant death (with 95-98 percent sensitivity and 5 percent false detection). If the results are borderline, another screening in the second trimester may be desired.

Second trimester

Most women will have a second trimester ultrasound between 18-20 weeks gestation, when the baby actually starts to look like a baby! Organs and skeletal structure are visible, and the gender is often distinguishable at this time. Besides checking the baby's position, the doctor will look for risk of congenital anomalies, such as heart defects or a cleft lip, and markers for chromosome anomalies.

A blood test for AFP (alpha-fetoprotein) level may be administered. AFP looks for neural tube defects (spina bifida and a brain disorder called anencephaly). An elevated AFP can also be associated with an under-performing placenta which can cause stunted growth. If blood tests were not conducted in the first trimester, or if you choose an integrated first-and-second trimester screening, a blood test called a Quad Screen (for AFP, hCG , estriol, and inhibin A) is recommended. This test is less accurate than the first trimester screening with only 75 percent sensitivity in detecting Down syndrome.

Diagnostic tests

Amniocentesis and CVS are diagnostic tests that are sometimes recommended for older moms or, more often, following abnormal screenings during the standard blood tests. If you are scheduled for either an Amnio or CVS, you can also ask for a PreNatal Paternity Test at the same time. Removing any doubts about the paternity of your child early on in your pregnancy can help the new dad to become involved with your pregnancy and plan for your new baby. (what does he need to have the new baby placed under his healthcare/benefits package/family inheritance?)

Amniocentesis is an invasive test wherein a needle penetrates the uterus to extract amniotic fluid in order to test the growth of fetal cells. It is performed between 15 and 20 weeks gestation. It identifies chromosome anomalies with 99.9 percent accuracy, but it carries the risk of membrane rupture, infection and injury to the fetus. The risk of miscarriage is 1/300 to 1/400.

CVS (Chorionic Villius Sampling) is also invasive.

It presents a higher risk of miscarriage--about 1/100 to 1/200--but can be performed earlier, between 11 and 13 gestational weeks. This test studies chromosomes taken from the placenta; it is typically just as accurate as amniocentesis, but in 1/100 cases, an amniocentesis will also be required for better accuracy.

As soon as you make your appointment for your first trimester screening, write down any questions - perhaps keep a journal. One day you can show the journal to your new baby so that he or she knows how much you prepared for his/her arrival.

Amniocentesis Procedure and Paternity Tests

DNA Lady

on May 12, 2009 2:02 PM | Permalink

Amniocentesis is the withdrawal of a small amount of amniotic fluid (the fluid surrounding a developing fetus) from the uterus. The procedure is done in a doctor's office or a hospital, usually when a woman is about 16 weeks pregnant, counting the from the first day of her last menstrual period.
Before the procedure, the doctor performs an ultrasound or sonogram, which shows a picture of the uterus, the placenta, the amniotic fluid and the fetus on a screen. After reviewing the image, the doctor inserts a very thin needle through the woman's abdomen into the uterus and takes out approximately one ounce of amniotic fluid. This part of the procedure lasts only a few minutes. After the sample is taken, another ultrasound check is done.
Some women say that an amniocnetesis does not hurt at all, while others say they feel pressure or cramping during the procedure. Often, people find that waiting for the test results is the most difficult part.
Different tests can be performed ona sample of amniotic fluid, depending on why a particular pregnancy is at risk. At the same time, a prenatal paternity test can be performed to confirm paternity of the child. Confirming paternity early on in the pregnancy, allows both parents to participate in the pregnancy and preparation for the child.
Most women who decide to have an amniocentesis are at risk for having a baby with a chromosome abnormality. The amniotic fluid contains cells that have been shed from teh fetus. Any abnormality in chromsomes almost always lead to ser ious physical birth defects, mental retardation or both.
The most common chromosome abnormality is Down Syndrome, is caused by an extra #21 chromsome. The standard laboratory testing detects over 99% of chromosome abnormalities and results are usually available in 10 days. Results for prenatal paternity test, when an amniocentesis is the method, usually takes 5 business days.
Examples of inherited diseases that can be tested for prenatally include Tay-Sachs, cycstic fibrosis and sickel cell desease. Amniotic Fluid can also be tested for open neural tube defects, such as spina bifida and anencephaly when the spinal cord or brain fo the baby have not developed properly. AFP (a protein Alpha-fetoprotein) is mesured and detects over 90% of all open nural tube defects.
The American College of Obstetricians and Gynecologists recommends that all women, regardless of age, consider the option of amniocentesis for the diagnosis of chromosome abnormalities. In the past, only older women (over 35) were offered amniocentesis because the risk for the most common chromosome abnormalities was known to increase with maternal age. However, there are now non-invasive screening tests performed on a sample of a woman's blood that can more accurately identify her specific risk for common chromosome abnormalities.
Of course, a woman may choose not to have any testing at all. If a woman is unsure whether or not she should have an amniocentesis, she sould speak with her doctor, a genetic counselor or other specialist in genetics. At the same time, if paternity is in question, a woman can schedule a PreNatal Paternity Test with her local DNA collections expert.