How Down syndrome is diagnosed
One in every 700 babies is born with some form of Down syndrome. That may seem like a relatively small number — unless you are one of many anxious pregnant women who are awaiting test results.
Fortunately, there’s less cause for worry for pregnant women when there is a thorough investigation using DNA testing with early first-trimester prenatal screening tests. Concerned parents-to-be rely on Los Angeles’s best high-risk pregnancy specialist: Dr. Steve Rad. He is a well-known expert on prenatal screening for Down syndrome signs during pregnancy
What is Down syndrome?
Down syndrome, medically referred to as Trisomy 21, is a genetic disorder in which the baby is born with an extra chromosome 21. Normally, a baby has 46 chromosomes, 23 from each parent.
The genetic condition caused by the extra 21st chromosome is known as Down syndrome. These chromosome abnormalities pose mental and physical complications for the baby.
According to the Centers for Disease Control (CDC), the physical characteristics of a child born with Down syndrome include:
- A flattened face, especially the bridge of the nose
- Almond-shaped eyes that slant up
- A short neck
- Small ears
- A tongue that tends to stick out of the mouth
- Tiny white spots on the iris (colored part) of the eye
- Small hands and feet
- A single line across the palm (palmar crease)
- Small pinky fingers that sometimes curve toward the thumb
- Poor muscle tone or loose joints
- Shorter in height as children and adults
Typically, a Down syndrome baby will have a mild to moderately low IQ.
Down syndrome test in pregnancy
Despite popular belief, women of all ages, not just those over 35 years old (known as advanced maternal age) may have a child with Down syndrome. This is a very important point to understand. Screening and diagnostic DNA tests and detailed high-resolution ultrasounds are recommended for all pregnant people.
Down syndrome screening first trimester
The first trimester of pregnancy can begin with tests that indicate the likelihood of Down syndrome. These indicate a possibility of a genetic defect. A positive Down syndrome screening test requires further testing.
- Non-invasive prenatal testing or screening (NIPT or NIPS) test is performed with a sample of blood from the mother. When pregnant, a woman’s blood contains small fragments of the baby’s DNA. The NIPT determines whether there is an increased risk for certain genetic conditions.
Remember, the NIPT is a screening test, not a diagnostic inquiry. Dr. Rad will discuss the results and counsel parents about other tests that may be more concrete. This test is performed between 9-12 weeks. - The Down syndrome ultrasound measures the thickness of fluid behind the baby’s neck (nuchal translucency) as well as birth defects. If Down syndrome is suspected, further testing becomes available. This test is performed between 12-13 weeks.
Dr. Rad has special expertise and international training and has developed his own technique in advanced, high-resolution early first-trimester fetal anatomy and fetal echo ultrasounds performed between 11-13 weeks of gestation. In addition, he’s developed his own technique in early second-trimester fetal anatomy and fetal echo ultrasounds performed between 15-16 weeks of gestation. This is Dr. Rad’s signature “early fetal anatomy scan” in which he can look for birth defects very early on. His technique is unique, and early fetal anatomy ultrasounds are not currently readily or widely available in the area (or the nation).
Second trimester Down syndrome screening
The Maternal Serum Screen (MSS) is a blood test typically given between weeks 15 and 19 for all women. If the result says that there is an increased chance of Down syndrome, diagnostic testing is offered.
The diagnostic tests (CVS and/or amniocentesis) are somewhat more invasive than the blood screen tests and look for changes in the chromosomes that would indicate Down syndrome. The painless tests usually take about 20 minutes. Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby. These tests are typically performed between 11-22 weeks of pregnancy.
Down syndrome tests
These tests also reveal if the baby has a chance of having genetic diseases such as spina bifida, neural tube defects, trisomy 13, or trisomy 18.
- Chorionic villus sampling (CVS) — involves taking placenta cells via a needle with the help of ultrasound to look for Down syndrome signs. This test determines the number of chromosomes in the baby. The procedure is typically performed between 11-14 weeks into pregnancy.
- Amniocentesis— is a procedure in which amniotic fluid is removed from the uterus for testing. Amniotic fluid is the fluid that surrounds and protects a baby during pregnancy. This fluid contains fetal cells and various proteins. The procedure is typically performed after 15 weeks of gestation.
- Percutaneous umbilical blood sampling (PUBS) — also known as cordocentesis, the diagnostic procedure is used to evaluate blood from the umbilical cord. PUBS is used only when less invasive diagnostic procedures cannot provide conclusive results. This test is performed at 18-19 weeks.
Down syndrome screening risks
All three of these are invasive tests and come with some form of risk. Dr. Rad will discuss both positive and negative possibilities so you can give your consent and make an informed decision.
- CVS: Possible miscarriage, cramping, spotting, chills, fever, and leaking amniotic fluid.
- Amniocentesis: Small risk of miscarriage, infection, bleeding, or damage to the amniotic sac that surrounds the baby. A miscarriage can occur as many as one to two weeks after the test, though the first 24-48 hours is typically the danger zone. Rhesus disease (RH) occurs in mothers who have an Rh-negative blood type. When the baby’s blood enters the mother’s bloodstream, it starts to produce antibodies to attack it; Rhogam is given if indicated to prevent this from occurring. Club foot is a rare risk.
- PUBS: The most common risk is bleeding at the puncture site, which can be dangerous to the fetus. Umbilical cord hematoma, which can be fatal to the fetus. Vertical transmission, where a virus from the mother, such as HIV, is given to the baby.
Why choose Dr. Steve Rad for your Down syndrome testing?
Did you know that all pregnancies in the United States are at risk of becoming high-risk? Even a pregnancy that begins “low-risk” can become high-risk. That is no secret to double-board certified Dr. Steve Rad, an Obstetrician-Gynecologist with sub-specialty training in Maternal-Fetal Medicine / Perinatology.
Dr. Rad has been named a top Maternal-Fetal Medicine specialist in Los Angeles by Los Angeles Magazine for six years in a row.
Call us at (844) 473-6100 or schedule your consultation online. We are currently accepting new patients.
We are conveniently located for patients throughout Southern California and the Los Angeles area at locations in or near Beverly Hills, Santa Monica, West Los Angeles, West Hollywood, Culver City, Hollywood, Venice, Marina del Rey, Malibu, Manhattan Beach, Newport Beach, Irvine, and Downtown Los Angeles. We also offer in-home prenatal care and a fly-in program for out-of-town and international patients. Dr. Rad even travels to patients who need him throughout the U.S. and around the world.
If you can’t make it to Dr. Rad, he also offers virtual consultations worldwide.
Call (844) 473-6100 or click here to schedule online
