Lukes Maternal Fetal Medicine
What Are Genetic
Genetic counselors are Master’s level, certified professionals who help you understand scientific, medical and genetic information relating to your family history, medical history and/or pregnancy. They help clarify the risks for occurrence or recurrence of a genetic or inherited disorder or condition in specified family members. They help patients and families make sense of complex options for testing and interventions and explain the results of diagnostic tests. Based on a genetic counselor’s risk assessment, individuals and families are able to make informed medical decisions in a supportive environment that affirms their personal cultural, religious and ethical beliefs.
In addition to providing education and support services to families with genetic concerns, genetic counselors are also involved in coordinating testing and connecting patients and families with national and community-based informational resources, including support groups and funding agencies.
Genetic Counseling Services at St.
Genetic counseling services at St. Luke’s Maternal Fetal Medicine are provided by board certified genetic counselors. Our counselors have extensive experience in addressing the complex educational and emotional needs of families in the face of a diagnosis or risk of occurrence of a genetic disorder or birth defect. Based on the nature of our practice, the majority of the patients seen for genetic counseling at St. Luke’s Maternal Fetal Medicine are contemplating or undergoing pregnancy and have been referred by their primary care provider for discussion of risks to their unborn baby and diagnostic testing or screening options.
Is Genetic Counseling for You?
Your doctor may refer you to see a genetic counselor at St. Luke’s Maternal Fetal Medicine if:
- You are 35 years of age or older and considering a pregnancy or currently pregnant.
- You have had a previous child with mental retardation, an inherited disorder or a birth defect.
- You or your partner have, or are concerned that you may have, an inherited disorder or birth defect.
- You have had two or more miscarriages or babies who died in infancy and are pregnant or considering pregnancy.
- You are concerned that your job, lifestyle or medical history may pose a risk to a pregnancy (i.e. due to chemical, radiation, drug or medication exposure).
- You and your partner are related (i.e. first cousins).
- You would like information or testing regarding genetic defects occurring more frequently in your ethnic group.
- You have been told that your pregnancy may be at increased risk for complications or birth defects based on results of tests such as the multiple marker blood test (“triple” or “quad” screen) or an ultrasound test.
If You Are Pregnant: Testing for
During your pregnancy, your health care professional may offer you prenatal tests to gain information and reassurance regarding the health of your baby. Tests are routinely offered to all pregnant women. This testing can determine the level of risk in a given pregnancy for a variety of adverse outcomes, such as Down syndrome, spina bifida, and a severe chromosome abnormality called trisomy 18. Based on results of this test, further diagnostic testing, such as amniocentesis, may be recommended.
In certain specialized centers, like St. Luke's Maternal Fetal Medicine, a new highly accurate prenatal screening test is available. This test is available in early pregnancy. As early as 11 weeks after the first day of the woman's last menstrual period, the test utilizes a special ultrasound measurement of a pocket of fluid in the back of the baby's neck called the "nuchal translucency" or "NT". Babies with certain birth defects, in particular Down syndrome, tend to have larger amounts of fluid than usual, so this measurement can be used to calculate the risk for Down syndrome and certain other conditions (e.g. congenital heart defect or trisomy 18). The risk calculation usually includes the measurement of levels of certain proteins, or pregnancy hormones, in the mother's blood. The most accurate result comes from obtaining two blood samples from the mother, one at at the time of the NT measurement and the other at 15-18 weeks gestation. In a type of screening test called the Sequential Screen, a preliminary risk estimate is provided after the NT and first blood test, with a final, highly accurate result after the second blood draw. The pregnant woman may proceed with diagnostic testing (such as chorionic villus sampling or amniocentesis) if results of the first or second part of the screening are concerning. The Sequential Screen detects 91% of cases of Down syndrome, 90% of trisomy 18, 40% of congenital heart defects and 80% of fetal open neural tube defects (spina bifida).
Most doctors will also perform an ultrasound evaluation to measure the baby’s growth and check amniotic fluid levels, as well as to screen for visible birth defects. At St. Luke’s Maternal Fetal Medicine, we offer high- resolution (level II) ultrasound, a detailed type of ultrasound evaluation which combines the imaging capabilities of our highly specialized equipment with evaluation and interpretation by our board-certified specialists in Maternal Fetal Medicine: Clarence Blea, MD, Stacy Seyb, MD, Michael Koszalka, MD and Richard Lee, MD. Ultrasounds may also be performed by a certified sonographer, in which case a physician reviews and interprets the results. Depending on the results of ultrasound tests, further testing may be recommended.
In certain cases, invasive diagnostic testing is offered during pregnancy, if the pregnancy is determined to be at reasonably elevated risk for an abnormality detectable through this type of testing. Examples of this kind of test include chorionic villus sampling (or “CVS”) and amniocentesis. Using specialized techniques, a small fetal tissue sample is collected, which can then be tested for chromosomal or other specific abnormalities. With CVS, a small piece of placenta is obtained for testing using a catheter inserted through the cervix (the lower part of the uterus) or using a needle inserted through the abdomen. The cells of the placenta have the same chromosomal content as the baby's cells, so analysis of placental tissue can determine the chromosomal status of the fetus. Amniocentesis involves using a thin needle to collect a small amount of fluid from around the baby. This fluid contains skin cells of the baby, which can be tested for their chromosomal content. Analysis of amniotic fluid obtained through amniocentesis can also diagnose spina bifida in a fetus. In some cases, tissue samples obtained through CVS or amniocetesis may undergo other specialized tests.
Both CVS and amniocentesis offer highly accurate (greater than 99%) analysis of fetal chromosome makeup. Thus, conditions such as Down syndrome can be virtually ruled out. Amniocentesis will additionally detect up to 98% of cases of spina bifida. Due to the invasive nature of these tests, however, there is a small risk involved. If your doctor determines that CVS or amniocentesis may be appropriate for you, one of our genetic counselors can discuss the risks and benefits of these procedures with you in greater detail and assist you with scheduling the procedure of your choice.
Even with normal prenatal testing results, there is a small chance that a baby will be born with problems. There are many birth defects, genetic conditions and other abnormalities that no prenatal testing method can detect. The background risk for fetal abnormalities, only a minority of which are detectable through prenatal diagnosis, is 3-5%.
Fetal Chromosome Abnormalities and
Increased Maternal Age
It is now widely recognized that as a woman increases in age, her risk for a child with a chromosome abnormality, such as Down syndrome, increases. Down syndrome results when a fetus has an extra chromosome number 21. This results in three copies of chromosome 21 instead of the usual two. Another name for Down syndrome is “trisomy 21”. Down syndrome consists of a pattern of abnormalities including mental retardation, a characteristic physical appearance and medical problems (often including heart defects).
The risk for a child with Down syndrome increases with maternal age.
- A 20-year-old woman has about a one in 2000 chance of having a child with Down syndrome.
- At age 30, it is one in 952.
- By age 35, the chances increase to one in 385.
- At age 40, the risk is one in every 106 children.
- At 45, the chances are one in 30.
For information about genetic counseling, call: (208) 381-3088
St. Lukes Maternal Fetal Medicine
333 N. 1st Street, Suite 150
Boise, ID 83702