Topic 1: Case Information- Your Task Copy
As the physician in the case, you need to conduct a thorough medical and genetic history initially. Following that, be prepared to answer questions (and also raise issues) about 1) screening tests; 2) diagnostic tests; 3) estimates of the likelihood of Down syndrome (and other chromosomal alterations) for a 40-year-old woman; and 4) life outcomes for individuals with Down syndrome.
Note how the physician carefully listens to the patient frame her concerns. He then provides basic information, helping the patient raise questions, but not overwhelming her. Also, the physician discusses the mother’s risk for having a genetic condition; current best practice suggests the use of the word chance of having a specific condition.
Video Transcript
Dr. Thomas:
(With warmth) Good morning, Mrs. Abbott. I am Dr. Thomas. I understand that you want to talk about planning to have a baby.
Mrs. Abbott:
(With some reticence) Yes, Dr. Thomas. My husband and I have tried to have a baby for a long time, but have not succeeded in conceiving. We thought you might be able to offer some words of wisdom and maybe some cautions too!
Dr. Thomas:
I am very glad you came in to see me now. I find it very helpful to discuss a patient’s medical history, to evaluate any underlying medical conditions, and to provide information that might help my patient prepare for a healthy pregnancy. Do you have any initial questions before we begin the history?
Mrs. Abbott:
Yes, I do. Since my husband and I have tried to have a baby for so long, does that mean that if I ever do get pregnant, we’re likely to have a baby with problems at my age?
Dr. Thomas:
I really cannot answer that until we go through your entire medical and genetic history. I can say that age increases the risk of chromosomal alterations like Down syndrome, and other disorders. But, most mothers 40 or over DO NOT have children with these conditions. In fact, most children with Down syndrome are born to mothers under the age of 35.
Mrs. Abbott:
(With some concern.) Well, is there any way for me to know ahead of time if I am one of the mothers who will have this problem?
Dr. Thomas:
(Reassuringly.) Again, we need to get some basic information first. There are certain genetic conditions that run in families, although most chromosomal abnormalities such as Down syndrome are typically not inherited. When you become pregnant, we can offer you a diagnostic test for Down syndrome, typically amniocentesis or chorionic villus sampling (or what we call CVS). Some women don’t want to start with these procedures, because they involve a small degree of risk to the pregnancy, and they therefore elect to do screening tests first. Screening tests involve taking a sample of your blood, an ultrasound, or both. They give us an estimate of your risk, but unlike an amnio or CVS, screening tests will not give us a definitive diagnosis. First of all, though I am going to refer you to a reproductive endocrinologist and infertility specialist because your husband and you have tried for three years to conceive a child.
Mrs. Abbott:
We would like to see an infertility specialist, but what do you mean by screening tests after we become pregnant?
Dr. Thomas:
These are tests that help us determine the likelihood of your having a child with a chromosomal abnormality, like Down syndrome. Typically, we draw blood to look at the level of certain proteins which are associated with increased risk, and with some screening, we may also include an ultrasound to detect physical characteristics associated with Down syndrome. We can do screening in either your first or second trimester, depending upon how early in your pregnancy you might want to know. The problem with screening is that these tests just tell us whether you are at increased risk for having a child with a chromosomal abnormality. They don’t tell us whether you will have a child with any of these conditions. The tests may well say you have increased risk, and the baby will be perfectly normal, or in some cases, the tests will say you do not have increased risk, but you may still have a child with one of these conditions.
Mrs. Abbott:
(Ponderously) I see. But if they are so inaccurate, why do them?
? Decision Point: What would you say next?
Reflect for a minute on what you would say next, then check your answer against the suggestion below.
Suggested Response
The screening tests give you a good idea about whether you have a higher chance of having a baby with Down syndrome. Then you can use those results to decide if you want to go ahead and have a CVS or amnio. Again, some women decide to start with an amnio or CVS, which are near definitive, but do carry a small degree of risk to your pregnancy.
- Screening helps women to know if there is an increased chance that a baby has Down syndrome. They can use those results to decide whether to have a definitive diagnostic test (amniocentesis or CVS)
- There are different types of screening tests. Non-invasive prenatal screening or cell-freeDNA tests are more accurate than traditional screening tests but are still not considered diagnostic.
- Some women prefer to start with a definitive diagnostic test to know for sure whether or not the baby has Down syndrome.
- Diagnostic tests carry a small degree of risk of pregnancy loss.