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A Guide to First Trimester Prenatal Testing & Screening

One of the first steps you should take after finding out that you're pregnant is scheduling an appointment with your doctor to determine your prenatal care requirements. Your doctor will most likely set the first official prenatal test during your 6th or 8th week of pregnancy to begin monitoring your baby's development and screen for and rule out potential fetal problems or abnormalities. It is important to note that no screening method can diagnose birth defects; they can only indicate a higher risk for such problems, which helps determine whether you need to take further testing to determine your situation.

Prenatal Panel
The prenatal panel is a set of general tests that are usually conducted during the first trimester, and includes but is not limited to a complete blood count (CBC), blood typing, hepatitis panel, urine analysis, and rubella viral antigen screen. Other tests may be obtained based on the status of your health and pregnancy history if you have one. Your doctor will determine which of these tests you need to take and when. 

First Trimester Ultrasound
One of the simplest screening tests available, the ultrasound is used to visualize and examine the developing fetus, enabling the doctor to confirm the viability of the pregnancy and to determine: the date of conception; the number of fetuses; the location of the fetus prior to CVS or amniocentesis; and the risk for chromosomal abnormality. The ultrasound is performed any time during the first trimester, and takes between 5 to 30 minutes. It is both painless and harmless.

First Trimester Combined Screening
Comprising both an ultrasound screening and a blood test, the first trimester combined screening is used to determine the fetus's level of risk for chromosomal abnormalities. This test merely gives a statistical estimate of the risk and is by no means an actual diagnosis. Usually conducted between the 11th and 14th week of pregnancy, both the ultrasound and the blood test are harmless and painless. The only risk is receiving false positive results that require follow-up procedures which may potentially be harmful. If your screening results come out positive for chromosomal abnormalities, get a second opinion by another experienced physician just to be sure.

Chorionic Villus Sampling (CVS)
Usually performed for women over 35 years old or for those with a family history of genetic disorders, this diagnostic test is used to detect chromosomal abnormalities by extracting a small tissue sample from the chorionic villus, which are the finger-like projections of the placenta. The sample is collected either via the vagina and cervix (transcervical CVS) or by inserting a needle into the abdominal wall (transabdominal CVS); both methods last no more than 1-2 minutes and are very safe and accurate. The test is performed between the 10th and 13th weeks of pregnancy.

Integrated Screening
Much more accurate than the first trimester combined screening, the integrated screening makes use of both an ultrasound and two blood tests to determine the fetus's risk of genetic disorders and chromosomal abnormalities. The ultrasound and first blood test are usually performed between the 10th  and 14th week on the same day, while the second blood test is taken during the second trimester between the 16th  and 18th  week. The process is both painless and safe, and once you receive your results you can discuss with your doctor whether you need to have further testing.