Prenatal Diagnosis

What is prenatal diagnosis?

Prenatal diagnosis refers to the use of one or more tests to determine if a fetus (a developing baby) has a problem before birth.Hundreds of problems can be detected during pregnancy.These include chromosomal abnormalities such as Down syndrome as well as many single gene disorders such as cystic fibrosis,Tay-Sachs disease and sickle cell disease.Unfortunately,not all problems can be detected before delivery.

Many steps can be involved in prenatal diagnosis,and not everyone will choose the same path depending on their beliefs and concerns.In general there are two broad categories of tests that are available:screening and diagnostic.Screening tests gather information about the possibility of a birth defect in the pregnancy. Screening may include a careful family history,blood tests and an ultrasound exam. There is generally no risk to the pregnancy with screening tests. Diagnostic tests refer to the ability to accurately tell whether a fetus has a specific problem. Amniocentesis and chorionic villus sampling are commonly used diagnostic tests.

Who should think about prenatal diagnosis?

Prenatal genetic counseling and diagnosis is generally offered to the following people:

• Women who will be 34 years of age or more when their baby is born.
• Women and men who have had a child with a chromosomal abnormality.
• Women and men who are carriers of a known chromosomal rearrangement.
• Women who are carriers of an X-linked disease such as hemophilia, muscular dystrophy or fragile X syndrome.
• Women and men who are carriers of a single gene disorder that can be detected prenatally.
• Women and men who have had a child with a birth defect of the spinal cord or brain such as spina bifida,an open neural tube defect,or anencephaly.
• Women who are at increased risk due to positive maternal serum screening (the QUAD screen,triple screen or AFP test).
• Women who have been exposed to medications, drugs or other dangerous substances during their current pregnancy.
• Women who are at increased risk due to ultrasound findings.
• People of certain ethnic backgrounds.

For More Information

Download a pamphlet on prenatal diagnosis. Requires Acrobat Reader.

Prenatal Diagnosis at OHSU

Meet our doctors at the OHSU Perinatal Center where prenatal diagnosis is offered or call 503 418-4200 to schedule a consultation with a genetic counselor. See information about other Childbirth Services at OHSU.

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