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First Trimester Testing

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Obstetrix Medical Group offers new tests for pregnant women to learn of their personal risk of delivering a baby with Down syndrome, Trisomy 18 or Open Neural Tube Defects (ONTDs).

A positive result from one of these tests does not mean a baby has Down syndrome, Trisomy 18, or an ONTD. The results simply indicate that the child is at an increased risk for one of these conditions and offer parents the option of diagnostic testing.

Disorders

• Down syndrome — Down syndrome is the most common chromosome disorder. It typically results in varying degrees of mental retardation and physical disability.
• Trisomy 18 — Trisomy 18 is a rare disorder that can cause severe mental and physical disabilities. A high percentage of babies with this condition do not survive their first year.
• ONTDs — An ONTD is a major birth defect where the bones of the spine fail to close around the spinal cord, causing paralysis and other problems of the central nervous system.
  

Tests

First Trimester Fetal Combined Risk Assessment

• Down syndrome and Trisomy 18; performed during one visit and has two parts: blood work and a Nuchal Translucency (NT) ultrasound. An NT ultrasound measures the amount of fluid behind a baby’s neck. The more swelling detected, the higher the risk for chromosome disorder.
• Results are available in about a week. This test can detect 83 percent of Down syndrome babies and 80 percent of Trisomy 18 babies.
• Test offers the earliest possible warning and allows for the option of diagnostic testing such as Chorionic Villus Sampling (CVS). CVS is a diagnostic test that can be performed beginning at the 10^th week of pregnancy. It’s done either cervically or abdominally. The doctor performing the CVS will determine which method will present the highest likelihood of success and at the lowest risk. The tissue obtained during the CVS is tested to determine the baby’s chromosomal pattern. Please discuss the risk of this procedure with a genetic counselor or doctor.
• Test alone does not evaluate for the risk of ONTDs. Additional blood work is necessary to determine the risk of this type of birth defect.

Second Trimester Risk Assessment

• Down syndrome, Trisomy 18 and ONTDs: performed in one visit during the second trimester. It consists of blood work only. An estimate of the risk of Down syndrome, Trisomy 18, and ONTDs is made by determining certain levels in the blood during the second trimester.
• 81 percent of babies with Down syndrome, 80 percent with Trisomy 18, and 80 percent with ONTDs are detected through this test.
• Best test for those patients presenting to their doctor after their 14^th week of pregnancy.

Detailed Fetal Anatomical Ultrasound

• Pregnant women can also have a detailed fetal anatomical ultrasound performed to visualize her baby.
• Ultrasound looks closely at the baby’s developing organs and is combined with the others screens to further estimate the risk of abnormality.

Results

• A “positive result” does not necessarily mean that the baby has a problem. It does mean that he or she is at an increased risk.
• In some cases, a doctor may suggest a detailed fetal anatomical ultrasound in the second trimester to visualize the development of the baby.
• Abnormal results found during an NT ultrasound also indicate the baby is at an increased risk of other problems, including heart problems, chest malformations, and a variety of non-chromosomal syndromes. Therefore, a normal CVS or amniocentesis does not guarantee a normal baby.
• A CVS or amniocentesis may be offered to rule out Down syndrome and other chromosome problems. If medically indicated, additional testing to detect certain familial genetic disorders can be performed.