Screening for Fetal Chromosomal Abnormalities
Benefits, Risks, and Limitations: Having a baby is an exciting time and you probably have many questions and concerns about your pregnancy and especially about your baby. One of the first concerns of all pregnancies is whether of not your baby is chromosomally normal. It is important to remember that having a baby that is chromosomal, genetically, or structurally abnormal (such as Down Syndrome) is uncommon. You must choose what method of screening for chromosomal disorders (if any) you would like to use.
BENEFITS OF SCREENING:
Reassurance: In the great majority of cases, a screening test gives you the reassurance that the risk of your child having a chromosomal abnormality is acceptably low to you.
Further Testing: If the screening test indicates what you feel is an unacceptable risk, then you could choose to proceed with additional diagnostic testing to confirm whether or not the condition is present.
Intervention: If (rarely) you learn your baby is definitely affected by a condition such as Down Syndrome, you have choices to make. You could help your baby by having more frequent office visits, additional special testing, perhaps change when you deliver, where you deliver, who is present at the time of birth, what special equipment is needed and even have the time to discuss management of difficult findings or conditions at birth. You would potentially have more than six months to prepare psychologically and to become educated about the condition. You could be a better advocate for the child and be able to deal with friends and relatives in advance. You could do some grieving then try to become as constructive and nurturing as the time would allow. Another very different and profoundly personal approach choice would be to make arrangements to stop (Abort) the pregnancy.
RISKS OF SCREENING: Some couples desire to decline testing because of fear of false positives, or because they would not use the information to stop the pregnancy and would not find having the information prior to the birth of their baby to be helpful. Some couples even decline Genetic Counseling or the offer for information on this topic. Please understand that we must offer you genetic counseling. Nearly all of our patients who choose genetic counseling go to the Eastern Virginia Medical School Department of Maternal Fetal Medicine at 757-446-7938. It is up to you to decide how to use this offer. Most thoughtful people are comfortable with this information but some equally thoughtful individuals decline such information and testing. Agreeing to screen with blood tests and ultrasound or to have invasive testing such as Amniocentesis or Chorionic Villous sampling is a deeply personal choice.
LIMITATIONS OF SCREENING: A very large number of birth defects and many disabling conditions, such as cerebral palsy, epilepsy, autism, and learning disabilities, just to name a few, will not be detected by the type of testing being discussed here.
BACKGROUND: In the past, only women who were considered “at-risk” for chromosomal abnormality received screening and diagnostic testing. A woman may be considered at-risk based on her age, personal or family history. if she is over the age of 35 or with a first-degree relative (the expecting mother/father, maternal/paternal mother, father, sister, or brother) with a chromosomal problem. If you are in the “at-risk” category, your obstetrician may offer and encourage that you have an appointment with a genetic counselor. The genetic counselor will review your personal risk and offer additional screening and diagnostic testing. Even if you are in the “at-risk” category; it is still very unlikely that your baby will have a chromosomal abnormality.
A NEW STANDARD: The American College of Obstetrics & Gynecology has recommended that all women regardless of their age or risk be offered to screen for Down Syndrome and chromosomal abnormalities. There are now ways to offer screening and diagnostic testing earlier and more accurately. One major advantage of earlier testing is that in the event a serious abnormality is found, there is an opportunity for earlier and safer personal choices depending on the private beliefs of the parents. You must choose between first-trimester screening, second-trimester screening, or no screening.
FIRST TRIMESTER RISK TESTING:
NUCHAL TRANSLUCENCY TESTING: An ultrasound examination is done to measure the small fluid-filled space under the skin at the back of the baby’s neck. This is referred to as nuchal translucency (NT) and the information it provides is combined with a blood test from the mother. These tests have no direct risk to the fetus. First Trimester Risk Assessment has around an 82-87% detection rate for Down Syndrome. Five percent of all women tested will be told they are at increased risk for a Chromosomal problem. How much of an increased risk will be determined by the test results. What you should focus on is the starting risk based on your age and whether the screening test indicates an increased or decreased risk. Then you should consider the absolute risk number and decide if it is acceptable to you or if you need further clarification with a diagnostic test. It is very important to remember that these screening tests only evaluate the risk or chance, that your baby could have a chromosome problem, but cannot identify a chromosomal abnormality in the fetus.
NON-INVASIVE PRENATAL TESTING (NIPT): NIPT stands for Non-Invasive Prenatal Testing that looks at fetal DNA by taking a single sample of the mother’s blood. It is a new option for testing for trisomy 21, 18, and 13 together with sex chromosome abnormalities. This testing can be done at any time between 10-22 weeks. Results can take a week or more. This test is recommended for singleton pregnancies with advanced maternal age, an abnormal serum screen, personal or family history of aneuploidy, or abnormal ultrasound. While highly accurate, if positive it should be confirmed before final conclusion.
UNIVERSAL CARRIER SCREENING: This test screens simultaneously for more than 100 preventable genetic diseases for less than the price of a single test. The Universal Carrier Screening Test represents a major advance in carrier screening. Universal Genetic Test enables the determination of a person’s carrier status for more than 100 single-gene disorders using a single test. Individually rare yet collectively common, Mendelian disorders are a major public health problem, accounting for 10% of pediatric deaths. And 80% of cases occur in families with no history of the disease. This test can be used in place of traditional cystic fibrosis (CF) or Ashkenazi Jewish screens. The Universal Genetic Test simultaneously screens the carrier status for 100+ additional genetic diseases at extremely high accuracy. This test is also more thorough, screening for more mutations than other carrier tests for many disorders. For example, Counsyl screens for more than 100 CF mutations compared to 25 CF mutations recommended by the American College of Medical Genetics (ACMG) and the American College of Obstetricians and Gynecologists (ACOG).
SECOND TRIMESTER RISK TESTING: If you would rather not pursue first-trimester screening, second-trimester screening for chromosomal abnormalities may be performed at 16 weeks of pregnancy. According to The American College of Obstetrics & Gynecology, its accuracy and sensitivity is slightly lower but comparable to what is offered in the first-trimester screen. If you are interested in second-trimester screening, please discuss this with your Obstetrician. Screening results would be provided about a month later and therefore the option of stopping the pregnancy (abortion) is generally less safe and less private (though still well before the cut-off date of 23 6/7 weeks after which abortion is illegal in the state of Virginia).
DIAGNOSTIC TESTING: If your screening tests reveal an increased chance of a problem in your pregnancy, it does not automatically mean that your baby will be born with a problem. In fact, it is still very unlikely that your baby will have a problem. However, you will then be offered an opportunity to discuss your results further with a genetic counselor and you may elect to proceed with diagnostic testing. The diagnostic tests performed in pregnancy are Amniocentesis or Chorionic Villus Sampling (CVS). Although they are generally considered safe, diagnostic tests are invasive and carry a small risk of fetal loss (less than or equal to 1%). First-trimester diagnostic testing via CVS allows for answers and decisions sooner.
COSTS: Unfortunately, first-trimester risk assessment in low-risk patients may not be covered by your insurance. If your insurance company does not pay for this screening, your out-of-pocket cost (or cost-share) can be very high and should be known to you before you agree to test. Please be advised that not all insurance carriers cover the costs of Down Syndrome screening. It is a patient’s responsibility to check with their insurance carrier to ensure that the cost of the testing is covered. If your insurance company does not cover these tests, you will be responsible for payment should you pursue testing. Your insurance company will be billed separately for blood testing and for an ultrasound. Patients should confirm that blood testing and ultrasound (when necessary) are covered with their insurance carrier.
DO I NEED TO HAVE THESE TESTS? Screening and diagnostic tests are optional for you. No one has to have either a screening or a diagnostic test. If you decline to test and a condition is present you will have to live with the consequences. It is remarkable that some couples are comfortable with this and some couples are terrorized by it. It is intensely personal. You MUST participate in the decision and be able to own the consequences.
YOUR PERSONAL CHOICE: Generally speaking we encourage genetic counseling and support screening and testing that is desired by the parents – but the very personal choice remains yours. Having a baby involves many complex decisions that are best made on an individual basis. There is no one correct answer for all women. Just as an abnormal screening test does not guarantee that your baby has a chromosomal abnormality, a normal screening test does not guarantee a healthy baby. You must choose between first-trimester screening, second-trimester screening, or no screening.
PLEASE DO NOT FORGET THAT YOU WERE GIVEN THIS INFORMATION. If you would like more information, please ask for a referral to Eastern Virginia Medical School for Genetics counseling. Please be advised that if you are not considered to be at increased risk to have a child with a chromosomal or genetic problem (over 35 at birth, past history of an affected child), your insurance company may not cover the fee for this service.
WE ASK THAT YOU SIGN THE 10-12 WEEK PRENATAL TESTING CONSENT / REFUSAL FORM. THANK YOU !!!