Please note that we are seeing high patient volumes in the emergency department. Learn more >>.

Know before you go to the ER
Select the search type
  • Site
  • Web


It’s hard to wait 40 weeks to find out your baby’s gender and general health. At the Women & Infants Center, our highly experienced ultrasound and genetics team performs prenatal advanced testing to help you learn more about the baby you’re carrying.

A lab technician organizes samples for genetic testing

Experienced Prenatal Testing

Obtaining accurate and safe prenatal test results requires experience and expert skill. Our ultrasound and genetics specialists form one of the most experienced teams in the St. Louis region.

Each year, our sonographers, obstetricians and maternal-fetal medicine (high-risk pregnancy) specialists perform more than 5,000 ultrasounds and hundreds of amniocenteses and chorionic villus sampling (CVS) procedures. Our services include:


Our experienced sonographers and obstetricians perform routine obstetric ultrasounds (also called sonograms) between the 16th and 20th week of pregnancy to evaluate the baby’s health, anatomy and size.

Obstetric ultrasounds use high-frequency sound waves to produce an image on a screen of the baby in the mother's uterus. This painless, noninvasive procedure allows your provider to:

  • Detect anatomical defects or problems
  • Determine gender (although that can’t be determined with certainty)
  • Check placenta positioning
  • Evaluate fetal growth and development
  • Guide the provider when performing amniocenteses or chloric villainous sampling (CVS)
  • Detect a tubal or ectopic pregnancy

Gynecologic ultrasounds are also available for nonpregnant women with certain conditions such as abdominal or pelvic pain or irregular bleeding. Learn more about our gynecology services and the women’s health conditions we treat.

Prenatal genetic diagnostic testing

Prenatal genetic diagnostic tests can detect:

  • Certain birth defects
  • Genetic disorders such as Down syndrome
  • Neural tube defects such as spina bifida (open spine)
  • Hereditary disorders such as Tay-Sachs disease and sickle cell disease

Tests for these disorders carry a slight risk to the fetus. Therefore, usually only certain groups of at-risk patients should have these tests, to find out for certain if their fetus has a genetic disorder.

Our genetic counselors can help you and your family assess your risks. Higher-risk groups include:

  • Women who will be 35 or older at delivery
  • Couples who previously had a child with a chromosomal abnormality
  • Couples who are known carriers of a chromosome translocation (abnormality)
  • Women who are carriers for sex-linked disease such as hemophilia or muscular dystrophy
  • Couples who are known carriers or members of at-risk populations of certain hereditary disorders (such as sickle cell anemia in the African-American community or Tay-Sachs disease in the Jewish population)
  • Couples with a family history of neural tube defects such as spina bifida, anencephaly or encephalocele (birth defects involving the brain or spinal cord)
  • Couples who previously had or are at risk of having children with certain structural birth defects that may be detected by diagnostic ultrasound
  • Women who have had an abnormal maternal serum screen
  • Women with prenatal exposure to certain medications, drugs or certain viruses


This genetic prenatal diagnostic test evaluates cells from a pregnant woman’s amniotic fluid, the fluid that surrounds the baby, for abnormalities. To obtain these cells, an obstetrician inserts a small needle through the abdominal wall and into the amniotic sac using ultrasound guidance. The doctor withdraws a small amount of amniotic fluid, which contains cells shed from the fetal skin surface. A technician extracts these cells from the fluid and sends them to a laboratory for examination. Results are usually available within 14 days.

Chorionic villus sampling (CVS)

CVS is another type of genetic prenatal diagnostic test, usually performed in the first trimester between the 10th and 12th week of pregnancy. In CVS, a doctor passes a catheter (thin, flexible tube) through the woman's cervix and beneath the placenta, using ultrasound guidance. The doctor removes a small amount of villus tissue (tissues that carry the genetic makeup of the baby) from the placenta.

A pathologist (doctor who specializes in examining tissue samples for diagnosis) examines the chorionic villus sample in a laboratory. Results are usually available within 8 days. If your doctors detect a genetic disorder or chromosomal abnormality during a screening or diagnostic test, we may refer you to the Fetal Care Center for advice and treatment.

Contact Us

To make an appointment with a Washington University ultrasound and genetics specialist at the Women & Infants Center, call 855.925.0631.