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Blood Tests
Routine First
Trimester Blood Tests:
Hepatitis B, HIV (You will be
asked to sign a consent form which gives us permission to draw the HIV or refuse
the test), RPR (Reactive plasma reagent tests for syphilis and is mandated by
law), Rubella (German measles immunity), Blood type and screen (This tests your
blood type and antibody status), CBC (Complete blood count), TSH
(hypothyroidism), and Urinalysis
Genetic
Screening Tests for High Risk Patients:
Cystic
fibrosis testing, Tay-Sachs, Gaucher’s disease, Canavan disease, Sickle cell,
and Fragile X
Genetic Testing
for Diseases of Increased Frequency in the Ashkenazi Jewish Population (pdf)
Varicella (Chicken pox): This is
recommended if you do not know your immune status.
Second Trimester Blood
Tests:
Gestational Diabetes testing:
You
will be asked to take the one-hour glucola test between 24 and 28 weeks of your
pregnancy to screen for gestational diabetes. As a screening test, it is
used to determine which patients are at risk for gestational diabetes and need
the 3-hour glucose tolerance test. Your hemogram will also be repeated.
Hemogram:
A repeat test for anemia is performed. Patients will frequently be asked
to start iron supplementation after this test.
Rhogam:
If you are Rh negative, your partner’s blood type becomes important.
If he is Rh positive, you will need Rhogam to prevent Rh incompatibility. Rhogam
is administered as an injection after amniocentesis, at 28 weeks of your
pregnancy and after delivery if the baby is Rh positive.
Genetic Chromosomal Testing
First
trimester Screening:
Nuchal translucency screen (11-13
6/7 weeks gestation):
This is a non-invasive assessment of the baby’s risk
for Down’s syndrome. The test includes both an ultrasound and additional blood work. An education video can be viewed on the
Obstetrix Medical Group
website. This test is offered to all
pregnant patients regardless of age. It is a
combination of a finger stick blood test and an ultrasound that measures the
baby's nuchal (neck fold) thickness to determine if a baby is at higher risk of
having Trisomy 13 (Down's Syndrome) or Trisomy 18.
Genetic Counseling and Chorionic Villus
Sampling (CVS)
(10-12 weeks gestation):
CVS is an invasive test that involves taking a small amount of tissue from
the placenta. It may be performed after an abnormal nuchal thickness to
evaluate the fetus for chromosomal abnormalities if the fetus is at higher risk.
CVS chromosomal results are available earlier in pregnancy than amniocentesis
results. This test is performed by a perinatologist after genetic counseling.
Second
trimester Screening: California
Dept. of Health Genetic Disease Branch
Expanded AFP (15-20 weeks gestation):
Under 35 pdf
The Expanded Alpha
Fetal Protein blood test can detect some chromosomal or neural tube defects in
the fetus. It is offered to all patients under 35 and to those over 35 who
decline amniocentesis.
AFP Only (15-20
weeks gestation): AFP only pdf
AFP only tests for neural tube defects only and does not detect chromosomal
abnormalities. It is an adjunct to CVS or nuchal screening testing which
both screen for chromosomal defects, not neural tube defects.
Genetic Counseling, Level II
Ultrasound and
Amniocentesis (15-20 weeks gestation): Over 35
pdf
If you are over 35 or have a history of a genetic problem we recommend genetic
counseling and a Level II ultrasound. Risks and benefits of an amniocentesis
will be discussed with the genetic counselor prior to the ultrasound. These are
performed by a perinatologist.
Third Trimester
Group B Strep culture (36 weeks):
This is a vaginal
and perineal culture that tests for a bacteria that the baby does not normally
have immunity to and may cause an infant infection.
Glossary of
Selected Medical Terms
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