A nurse is providing education to a client who is scheduled to undergo chorionic villus sampling (CVS).

Which statement by the client indicates an understanding of this test?

A low level of AFP (<0.5 MoM) in a pregnant woman can indicate that the fetus has a chromosomal abnormality, such as Down syndrome or Edwards syndrome.

This is because these conditions affect the development of the fetal liver, which produces AFP.

Choice A is wrong because neural tube defects, such as spina bifida, are associated with high levels of AFP (>2.5 MoM) in the maternal blood.

This is because AFP can leak from the open spinal canal of the fetus into the amniotic fluid and then into the maternal blood.

Choice C is wrong because maternal weight-related factors do not affect the level of AFP in the maternal blood.

However, they can affect the interpretation of the AFP test results, as the test needs to be adjusted for maternal weight, age, ethnicity, and gestational age.

Choice D is wrong because fetal demise (death) can also cause high levels of AFP in the maternal blood, as the AFP from the dead fetus can leak into the amniotic fluid and then into the maternal blood.

Normal ranges of AFP in pregnant women vary depending on the gestational age and the method of measurement.

Generally, normal levels of AFP are below 10 ng/ml in nonpregnant adults and below 2.5 MoM in pregnant women.

To measure the fetal heart rate (FHR) in response to fetal movements.

This is because the FHR should increase by at least 15 beats per minute for at least 15 seconds when the fetus moves, which indicates a healthy and reactive fetus.

This is called an acceleration.

Choice B is wrong because the uterine contractions are not related to the fetal movements or the button pressing.

The uterine contractions are measured by a tocodynamometer or an intrauterine pressure catheter.

Choice C is wrong because the fetal oxygenation and neurological function are not directly measured by the button pressing.

The fetal oxygenation can be assessed by the FHR variability and decelerations, while the neurological function can be evaluated by other tests such as biophysical profile or fetal acoustic stimulation.

Choice D is wrong because the fetal well-being and hypoxia or distress are not indicated by the button pressing alone.

The fetal well-being and hypoxia or distress are determined by the FHR patterns, such as baseline, variability, accelerations and decelerations.