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.