2.6: Prenatal Assessment
- Page ID
- 233824
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Several assessments are suggested to women as part of their routine prenatal care to find conditions that may increase the risk of complications for the mother and fetus These can include blood and urine analyses and screening and diagnostic tests for birth defects.
Ultrasound
Ultrasound is one of the main screening tests done in combination with blood tests. Ultrasound is a test in which sound waves are used to examine the fetus. There are two general types. Transvaginal ultrasounds are used in early pregnancy, while transabdominal ultrasounds are more common and used after 10 weeks of pregnancy (typically, 16 to 20 weeks).
Ultrasounds are used to check the fetus for defects or problems. It can also find out the age of the fetus, location of the placenta, fetal position, movement, breathing and heart rate, amount of amniotic fluid in the uterus, and number of fetuses. Most women have at least one ultrasound during pregnancy, but if problems are noted, additional ultrasounds may be recommended.
When diagnosis of a birth defect is necessary, ultrasounds help guide the more invasive diagnostic tests of amniocentesis and chorionic villus sampling. Amniocentesis is a procedure in which a needle is used to withdraw a small amount of amniotic fluid and cells from the sac surrounding the fetus and later tested.
Image Source: Transvaginal Ultrasound Overview. Advanced OBDYN Institute. TopLine MD Alliance,
Amniocentesis
When diagnosis of a birth defect is necessary, ultrasounds help guide the more invasive diagnostic test of amniocentesis. Amniocentesis is a procedure in which a needle is used to withdraw a small amount of amniotic fluid and cells from the sac surrounding the fetus and later tested.
Amniocentesis can be used to diagnose many different gene and chromosome problems in the baby, including:
- Anencephaly (when the baby is missing a large portion of the brain)
- Down syndrome
- Rare metabolic disorders that are passed down through families
- Other genetic problems, like trisomy 18 (also known as Edwards syndrome)
- Infections in the amniotic fluid
Image Source: Amniotic fluid test (AFT). Amneotesis. Wikipedia.com.
Chorionic Villus Sampling
Ultrasounds help guide the diagnostic test Chorionic Villus Sampling, a procedure entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or another procedure, percutaneous umbilical cord blood sampling, and is the preferred technique before 15 weeks. Both amniocentesis and chorionic villus sampling have a risk of miscarriage, and consequently they are not done routinely.
Sources
- "Amniocentesis." MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated Jun 2024; cited 2020 Jul 1].
- Lally, Martha and Suzanne Valentine-French. Lifespan Development: A Psychological Perspective. Licensed under CC BY-NC-SA 3.0